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Christophe Geuzaine and Jean-François Remacle
Gmsh is an automatic 3D finite element mesh generator with build-in pre- and post-processing facilities. This is the Gmsh Reference Manual for Gmsh 2.2 (July, 15 2008).
Copying conditions Terms and conditions of use. 1. Overview What is Gmsh? 2. General tools Description of general commands and options. 3. Geometry module Description of all Geometry commands. 4. Mesh module Description of all Mesh commands. 5. Solver module Description of all Solver commands. 6. Post-processing module Description of all Post-Processing commands. 7. Tutorial A step-by-step tutorial. 8. Running Gmsh How to run Gmsh on your operating system. 9. File formats Input and output file formats. 10. Programming notes Random notes for developers. 11. Bugs, versions and credits Contact information and ChangeLog A. Tips and tricks Some tips to make your life easier with Gmsh. B. Frequently asked questions The Gmsh FAQ C. License Complete copy of the license. Concept index Index of concepts. Syntax index Index of reserved keywords in the Gmsh language.
-- The Detailed Node Listing ---
Overview
General tools
2.1 Expressions 2.2 Operators 2.3 Built-in functions 2.4 User-defined functions 2.5 Loops and conditionals 2.6 General commands 2.7 General options
Expressions
2.1.1 Floating point expressions 2.1.2 Character expressions 2.1.3 Color expressions
Geometry module
3.1 Geometry commands 3.2 Geometry options
Geometry commands
3.1.1 Points 3.1.2 Lines 3.1.3 Surfaces 3.1.4 Volumes 3.1.5 Extrusions 3.1.6 Transformations 3.1.7 Miscellaneous
Mesh module
4.1 Elementary vs. physical entities 4.2 Mesh commands 4.3 Mesh options
Mesh commands
4.2.1 Characteristic lengths 4.2.2 Structured grids 4.2.3 Miscellaneous
Solver module
5.1 Solver options 5.2 Solver example
Post-processing module
6.1 Post-processing commands 6.2 Post-processing plugins 6.3 Post-processing options
Tutorial
7.1 `t1.geo' 7.2 `t2.geo' 7.3 `t3.geo' 7.4 `t4.geo' 7.5 `t5.geo' 7.6 `t6.geo' 7.7 `t7.geo' 7.8 `t8.geo' 7.9 `t9.geo'
Running Gmsh
8.1 Interactive mode 8.2 Non-interactive mode 8.3 Command-line options 8.4 Mouse actions 8.5 Keyboard shortcuts
File formats
9.1 MSH ASCII file format 9.2 MSH binary file format 9.3 Node ordering 9.4 Legacy formats
Legacy formats
9.4.1 MSH file format version 1.0 9.4.2 POS ASCII file format 9.4.3 POS binary file format
Programming notes
10.1 Main code structure 10.2 Coding style 10.3 Option handling
Bugs, versions and credits
11.1 Bugs 11.2 Versions 11.3 Credits
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Gmsh is "free software"; this means that everyone is free to use it and to redistribute it on a free basis. Gmsh is not in the public domain; it is copyrighted and there are restrictions on its distribution, but these restrictions are designed to permit everything that a good cooperating citizen would want to do. What is not allowed is to try to prevent others from further sharing any version of Gmsh that they might get from you.
Specifically, we want to make sure that you have the right to give away copies of Gmsh, that you receive source code or else can get it if you want it, that you can change Gmsh or use pieces of Gmsh in new free programs, and that you know you can do these things.
To make sure that everyone has such rights, we have to forbid you to deprive anyone else of these rights. For example, if you distribute copies of Gmsh, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must tell them their rights.
Also, for our own protection, we must make certain that everyone finds out that there is no warranty for Gmsh. If Gmsh is modified by someone else and passed on, we want their recipients to know that what they have is not what we distributed, so that any problems introduced by others will not reflect on our reputation.
The precise conditions of the license for Gmsh are found in the General Public License that accompanies the source code (see section C. License). Further information about this license is available from the GNU Project webpage http://www.gnu.org/copyleft/gpl-faq.html. Detailed copyright information can be found in 11.3 Credits.
The source code and various pre-compiled versions of Gmsh (for Unix, Windows and Mac OS) can be downloaded from the webpage http://geuz.org/gmsh/.
If you use Gmsh, we would appreciate that you mention it in your work. References, as well as the latest news about Gmsh development, are always available on http://geuz.org/gmsh/. Please send all Gmsh-related questions to the public Gmsh mailing list at gmsh@geuz.org.
If you want to integrate Gmsh into a closed-source software, or want to sell a modified closed-source version of Gmsh, please contact one of the authors. You can purchase a version of Gmsh under a different license, with "no strings attached" (for example allowing you to take parts of Gmsh and integrate them into your own proprietary code).
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Gmsh is an automatic three-dimensional finite element mesh generator with built-in pre- and post-processing facilities. Its design goal is to provide a simple meshing tool for academic problems with parametric input and advanced visualization capabilities.
Gmsh is built around four modules: geometry, mesh, solver and post-processing. All geometrical, mesh, solver and post-processing instructions are prescribed either interactively using the graphical user interface (GUI) or in ASCII data files using Gmsh's own scripting language. Interactive actions generate language bits in the input files, and vice versa. This makes it possible to automate all treatments, using loops, conditionals and external system calls. A brief description of the four modules is given hereafter.
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Gmsh uses a boundary representation ("b-rep") to describe geometries. Models are created in a bottom-up flow by successively defining points, oriented lines (line segments, circles, ellipses, splines, ...), oriented surfaces (plane surfaces, ruled surfaces, triangulated surfaces, ...) and volumes. Compound groups of geometrical entities (called "physical groups") can also be defined, based on these elementary geometric entities. Gmsh's scripting language allows all geometrical entities to be fully parameterized.
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A finite element mesh is a tessellation of a given subset of the three-dimensional space by elementary geometrical elements of various shapes (in Gmsh's case: lines, triangles, quadrangles, tetrahedra, prisms, hexahedra and pyramids), arranged in such a way that if two of them intersect, they do so along a face, an edge or a node, and never otherwise. All the finite element meshes produced by Gmsh are considered as "unstructured", even if they were generated in a "structured" way (e.g., by extrusion). This implies that the elementary geometrical elements are defined only by an ordered list of their nodes but that no predefined order relation is assumed between any two elements.
The mesh generation is performed in the same bottom-up flow as the geometry creation: lines are discretized first; the mesh of the lines is then used to mesh the surfaces; then the mesh of the surfaces is used to mesh the volumes. In this process, the mesh of an entity is only constrained by the mesh of its boundary(1). This automatically assures the conformity of the mesh when, for example, two surfaces share a common line. But this also implies that the discretization of an "isolated" (n-1)-th dimensional entity inside an n-th dimensional entity does not constrain the n-th dimensional mesh. Every meshing step is constrained by the characteristic length field, which can be uniform, specified by characteristic lengths associated with points in the geometry, or defined by general "fields" (a scalar field defined on another mesh using post-processing view, threshold fields associated with point or line "attractors", etc.).
For each meshing step, all structured mesh directives are executed first, and serve as additional constraints for the unstructured parts (2).
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External solvers can be interfaced with Gmsh through Unix or TCP/IP sockets, which permits to launch external computations and to collect and process the results directly from within Gmsh's post-processing module. The default solver interfaced with Gmsh is GetDP (http://www.geuz.org/getdp/). Examples on how to interface solvers written in C, C++, Perl and Python are available in the source distribution (in the `utils/solvers/' directory).
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Gmsh can load and manipulate multiple post-processing scalar, vector or tensor maps along with the geometry and the mesh. Scalar fields are represented by iso-value lines/surfaces or color maps, while vector fields are represented by three-dimensional arrows or displacement maps. Post-processing functions include section computation, offset, elevation, boundary and component extraction, color map and range modification, animation, vector graphic output, etc. All the post-processing options can be accessed either interactively or through the input ASCII text files. Scripting permits to automate all post-processing operations, as for example to create animations. User-defined operations can also be performed on post-processing views through dynamically loadable plugins.
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Gmsh is a (relatively) small program, and was principally developed "in academia, to solve academic problems"... Nevertheless, over the years, many people outside universities have found Gmsh useful in their day-to-day jobs. Here is a tentative list of what Gmsh does best:
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Due to its historical background and limited developer manpower, Gmsh has also some (a lot of?) weaknesses:
If you have the skills and some free time, feel free to join the project! We gladly accept any code contributions (see section 10. Programming notes) to remedy the aforementioned (and all other) shortcomings...
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Here are the rules we tried to follow when writing this user's guide. Note that metasyntactic variable definitions stay valid throughout the manual (and not only in the sections where the definitions appear).
this
.
:
) after a metasyntactic variable separates the variable
from its definition.
<
>
pairs.
|
.
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All Gmsh ASCII text input files support both C and C++ style comments:
/*
and */
pairs is ignored;
//
is ignored.
These commands won't have the described effects inside double quotes or inside keywords. Also note that `white space' (spaces, tabs, new line characters) is ignored inside all expressions.
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This chapter describes the general commands and options that can be used in Gmsh's ASCII text input files. By "general", we mean "not specifically related to one of the geometry, mesh, solver or post-processing modules". Commands peculiar to these modules will be introduced in 3. Geometry module, 4. Mesh module, 5. Solver module, and 6. Post-processing module, respectively.
Note that, if you are just beginning to use Gmsh, or just want to see what Gmsh is all about, you really don't need to read this chapter and the four next ones. Just have a quick look at 8. Running Gmsh, and go play with the graphical user interface, running the tutorials and demonstration files bundled in the distribution! Most of the commands and options described in the following chapters are available interactively in the GUI, so you don't need to worry about Gmsh's internals for creating your first geometries, meshes and post-processing plots. Once you master the tutorial (read the source files: they are heavily commented--see 7. Tutorial), you might want to come back here to learn more about the specific syntax of Gmsh's commands and esoteric options.
2.1 Expressions 2.2 Operators 2.3 Built-in functions 2.4 User-defined functions 2.5 Loops and conditionals 2.6 General commands 2.7 General options
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The two constant types used in Gmsh are real and string (there is no integer type). These types have the same meaning and syntax as in the C or C++ programming languages.
2.1.1 Floating point expressions 2.1.2 Character expressions 2.1.3 Color expressions
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Floating point expressions (or, more simply, "expressions") are denoted by the metasyntactic variable expression (remember the definition of the syntactic rules in 1.7 Syntactic rules used in this document), and are evaluated during the parsing of the data file:
expression: real | string | string [ expression ] | # string [ ] | ( expression ) | operator-unary-left expression | expression operator-unary-right | expression operator-binary expression | expression operator-ternary-left expression operator-ternary-right expression | built-in-function | real-option | GetValue("string", expression) |
Such expressions are used in most of Gmsh's commands. The third and fourth cases in this definition permit to extract one item from a list (see below) and get the size of a list, respectively. The operators operator-unary-left, operator-unary-right, operator-binary, operator-ternary-left and operator-ternary-right are defined in 2.2 Operators. For the definition of built-in-functions, see 2.3 Built-in functions. The various real-options are listed in 2.7 General options, 3.2 Geometry options, 4.3 Mesh options, 5.1 Solver options, and 6.3 Post-processing options.
The last case in the definition allows to ask the user for a value
interactively. For example, inserting GetValue("Value of parameter
alpha?", 5.76)
in an input file will query the user for the value of a
certain parameter alpha, assuming the default value is 5.76. If the option
General.NoPopup
is set (see section 2.7 General options), no question is
asked and the default value is automatically used.
List of expressions are also widely used, and are defined as:
expression-list: expression-list-item <, expression-list-item> ... |
with
expression-list-item: expression | expression : expression | expression : expression : expression | string [ ] | string [ { expression-list } ] | Point { expression } | transform | extrude |
The second case in this last definition permits to create a list containing the range of numbers comprised between two expressions, with a unit incrementation step. The third case also permits to create a list containing the range of numbers comprised between two expressions, but with a positive or negative incrementation step equal to the third expression. The fourth case permits to reference an expression list. The fifth case permits to reference an expression sublist (whose elements are those corresponding to the indices provided by the expression-list). The sixth case permits to retrieve the coordinates of a given geometry point (see section 3.1.1 Points). The last two cases permit to retrieve the indices of entities created through geometrical transformations and extrusions (see 3.1.6 Transformations, and 3.1.5 Extrusions).
To see the practical use of such expressions, have a look at the first
couple of examples in 7. Tutorial. Note that, in order to lighten the
syntax, you can always omit the braces {}
enclosing an
expression-list if this expression-list only contains a single
item. Also note that a braced expression-list can be preceded by a
minus sign in order to change the sign of all the
expression-list-items.
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Character expressions are defined as:
char-expression: "string" | Today | StrPrefix ( char-expression ) | StrRelative ( char-expression ) | StrCat ( char-expression , char-expression ) | Sprintf ( char-expression , expression-list ) | Sprintf ( char-expression ) Sprintf ( char-option ) |
The third and fourth cases in this definition permit to take the
prefix (e.g. to remove the extension) or the relative path of a string. The
fifth case permits to concatenate two character expressions, and the sixth
and seventh are equivalent to the sprintf
C function (where
char-expression is a format string that can contain floating point
formatting characters: %e
, %g
, etc.). The last case permits to
use the value of a char-option as a char-expression. The
various char-options are listed in 2.7 General options,
3.2 Geometry options, 4.3 Mesh options, 5.1 Solver options, and
6.3 Post-processing options.
Character expressions are mostly used to specify non-numeric options and input/output file names. See 7.8 `t8.geo', for an interesting usage of char-expressions in an animation script.
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Colors expressions are hybrids between fixed-length braced expression-lists and strings:
color-expression: string | { expression, expression, expression } | { expression, expression, expression, expression } | color-option |
The first case permits to use the X Windows names to refer to colors,
e.g., Red
, SpringGreen
, LavenderBlush3
, ...
(see `Common/Colors.h' in Gmsh's source tree for a complete list). The
second case permits to define colors by using three expressions to specify
their red, green and blue components (with values comprised between 0 and
255). The third case permits to define colors by using their red, green and
blue color components as well as their alpha channel. The last case permits
to use the value of a color-option as a color-expression. The
various color-options are listed in 2.7 General options,
3.2 Geometry options, 4.3 Mesh options, 5.1 Solver options, and
6.3 Post-processing options.
See 7.3 `t3.geo', for an example of the use of color expressions.
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Gmsh's operators are similar to the corresponding operators in C and C++. Here is the list of the unary, binary and ternary operators currently implemented.
operator-unary-left:
-
!
operator-unary-right:
++
--
operator-binary:
^
*
/
%
+
-
==
!=
>
>=
<
<=
&&
||
||
is evaluated even if the first one is true).
operator-ternary-left:
?
:
The evaluation priorities are summarized below(3) (from stronger to
weaker, i.e., *
has a highest evaluation priority than +
).
Parentheses ()
may be used anywhere to change the order of
evaluation:
()
, []
, .
, #
^
!
, ++
, --
, -
(unary)
*
, /
, %
+
, -
<
, >
, <=
, >=
==
, !=
&&
||
?:
=
, +=
, -=
, *=
, /=
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A built-in function is composed of an identifier followed by a pair of parentheses containing an expression-list (the list of its arguments)(4). Here is the list of the built-in functions currently implemented:
build-in-function:
Acos ( expression )
Asin ( expression )
Atan ( expression )
Atan2 ( expression, expression )
Ceil ( expression )
Cos ( expression )
Cosh ( expression )
Exp ( expression )
Fabs ( expression )
Fmod ( expression, expression )
Floor ( expression )
Hypot ( expression, expression )
Log ( expression )
Log10 ( expression )
Modulo ( expression, expression )
Fmod( expression, expression )
.
Rand ( expression )
Sqrt ( expression )
Sin ( expression )
Sinh ( expression )
Tan ( expression )
Tanh ( expression )
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User-defined functions take no arguments, and are evaluated as if a file
containing the function body was included at the location of the Call
statement.
Function string
Function
string
', and can contain any Gmsh command.
Return
Call string;
See 7.5 `t5.geo', for an example of a user-defined function.
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Loops and conditionals are defined as follows, and can be imbricated:
For ( expression : expression )
For ( expression :
expression )
' and the matching EndFor
are executed.
For ( expression : expression : expression )
For ( expression : expression :
expression )
' and the matching EndFor
are executed.
For string In { expression : expression }
For string In {
expression : expression }
' and the matching EndFor
are
executed.
For string In { expression : expression : expression }
For string In { expression :
expression : expression }
' and the matching EndFor
are
executed.
EndFor
For
command.
If ( expression )
If ( expression )
' and the matching
Endif
is evaluated if expression is non-zero.
EndIf
If
command.
See 7.5 `t5.geo', for an example of For
and If
commands. Gmsh
does not provide any Else
(or similar) command at the time of this
writing.
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The following commands can be used anywhere in a Gmsh ASCII text input file:
string = expression;
Pi
GMSH_MAJOR_VERSION
GMSH_MINOR_VERSION
GMSH_PATCH_VERSION
MPI_Size
MPI_Rank
newp
newp
permits to know the highest number already attributed (plus
one). This is mostly useful when writing user-defined functions
(see section 2.4 User-defined functions) or general geometric primitives, when one
does not know a priori which numbers are already attributed, and
which ones are still available.
newl
news
newv
newll
newsl
newreg
newreg
returns the
maximum of newp
, newl
, news
, newv
and all
physical entity numbers(5).
string [ ] = { };
string[]
with an
empty list.
string [ ] = { expression-list };
string[]
with the
list expression-list, or affects expression-list to an
existing expression list identifier. (Remember the remark we made when
we defined expression-lists: the braces enclosing an
expression-list are optional if the list only contains a single
item.)
string [ { expression-list } ] = { expression-list };
real-option = expression;
char-option = char-expression;
color-option = color-expression;
string | real-option += expression;
string | real-option -= expression;
string | real-option *= expression;
string | real-option /= expression;
string [ ] += { expression-list };
string [ { expression-list } ] += { expression-list };
string [ { expression-list } ] -= { expression-list };
string [ { expression-list } ] *= { expression-list };
string [ { expression-list } ] /= { expression-list };
Exit;
Printf ( char-expression , expression-list );
Printf
is equivalent to the printf
C function:
char-expression is a format string that can contain formatting
characters (%f
, %e
, etc.). Note that all expressions
are evaluated as floating point values in Gmsh (see section 2.1 Expressions), so
that only valid floating point formatting characters make sense in
char-expression. See 7.5 `t5.geo', for an example of the use of
Printf
.
Printf ( char-expression , expression-list ) > char-expression;
Printf
above, but output the expression in a file.
Printf ( char-expression , expression-list ) >> char-expression;
Printf
above, but appends the expression at the end of
the file.
Merge char-expression;
Draw;
BoundingBox;
BoundingBox { expression, expression, expression, expression, expression, expression };
Delete All;
Delete Physicals;
Mesh expression;
Print char-expression;
Print.Format
(see section 2.7 General options). If the path in
char-expression is not absolute, char-expression is appended to
the path of the current file.
Sleep expression;
System char-expression;
Include char-expression;
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Here is the list of the general char-options, real-options and color-options (in that order--check the default values to see the actual types). Most of these options are accessible in the graphical user interface, but not all of them. When running Gmsh interactively, changing an option in the ASCII text input file will modify the option in the GUI in real time. This permits for example to resize the graphical window in a script, or to interact with animations in the script and in the GUI at the same time.
Gmsh's default behavior is to save some of these options in a per-user
"session resource" file (General.SessionFileName
) every time Gmsh
is shut down. This permits for example to automatically remember the size
and location of the windows or which fonts to use. Other options can be
saved in a per-user "option" file (General.OptionsFileName
),
automatically loaded by Gmsh every time it starts up, by using the
`Tools->Options->Save as defaults' menu.
General.AxesFormatX
"%.3g"
General.OptionsFileName
General.AxesFormatY
"%.3g"
General.OptionsFileName
General.AxesFormatZ
"%.3g"
General.OptionsFileName
General.AxesLabelX
""
General.OptionsFileName
General.AxesLabelY
""
General.OptionsFileName
General.AxesLabelZ
""
General.OptionsFileName
General.DefaultFileName
"untitled.geo"
General.OptionsFileName
General.Display
""
-
General.ErrorFileName
".gmsh-errors"
General.OptionsFileName
General.FileName
""
-
General.FltkTheme
""
General.OptionsFileName
General.GraphicsFont
"Helvetica"
General.OptionsFileName
General.OptionsFileName
".gmsh-options"
General.SessionFileName
General.SessionFileName
".gmshrc"
-
General.TextEditor
"open -t %s"
General.OptionsFileName
General.TmpFileName
".gmsh-tmp"
General.SessionFileName
General.WebBrowser
"open %s"
General.OptionsFileName
General.AlphaBlending
1
General.OptionsFileName
General.Antialiasing
0
General.OptionsFileName
General.ArrowHeadRadius
0.12
General.OptionsFileName
General.ArrowStemLength
0.56
General.OptionsFileName
General.ArrowStemRadius
0.02
General.OptionsFileName
General.Axes
0
General.OptionsFileName
General.AxesMikado
0
General.OptionsFileName
General.AxesAutoPosition
1
General.OptionsFileName
General.AxesMaxX
1
General.OptionsFileName
General.AxesMaxY
1
General.OptionsFileName
General.AxesMaxZ
1
General.OptionsFileName
General.AxesMinX
0
General.OptionsFileName
General.AxesMinY
0
General.OptionsFileName
General.AxesMinZ
0
General.OptionsFileName
General.AxesTicsX
5
General.OptionsFileName
General.AxesTicsY
5
General.OptionsFileName
General.AxesTicsZ
5
General.OptionsFileName
General.BackgroundGradient
1
General.OptionsFileName
General.Clip0
0
-
General.Clip0A
1
-
General.Clip0B
0
-
General.Clip0C
0
-
General.Clip0D
0
-
General.Clip1
0
-
General.Clip1A
1
-
General.Clip1B
0
-
General.Clip1C
0
-
General.Clip1D
0
-
General.Clip2
0
-
General.Clip2A
1
-
General.Clip2B
0
-
General.Clip2C
0
-
General.Clip2D
0
-
General.Clip3
0
-
General.Clip3A
1
-
General.Clip3B
0
-
General.Clip3C
0
-
General.Clip3D
0
-
General.Clip4
0
-
General.Clip4A
1
-
General.Clip4B
0
-
General.Clip4C
0
-
General.Clip4D
0
-
General.Clip5
0
-
General.Clip5A
1
-
General.Clip5B
0
-
General.Clip5C
0
-
General.Clip5D
0
-
General.ClipFactor
5
-
General.ClipOnlyDrawIntersectingVolume
0
General.OptionsFileName
General.ClipOnlyVolume
0
General.OptionsFileName
General.ClipPositionX
650
General.SessionFileName
General.ClipPositionY
150
General.SessionFileName
General.ClipWholeElements
0
General.OptionsFileName
General.ColorScheme
1
General.OptionsFileName
General.ConfirmOverwrite
1
General.OptionsFileName
General.ContextPositionX
650
General.SessionFileName
General.ContextPositionY
150
General.SessionFileName
General.DoubleBuffer
1
General.OptionsFileName
General.DrawBoundingBoxes
0
General.OptionsFileName
General.ExpertMode
0
General.OptionsFileName
General.FastRedraw
0
General.OptionsFileName
General.FieldPositionX
650
General.SessionFileName
General.FieldPositionY
550
General.SessionFileName
General.FieldHeight
300
General.SessionFileName
General.FieldWidth
300
General.SessionFileName
General.FileChooserPositionX
200
General.SessionFileName
General.FileChooserPositionY
200
General.SessionFileName
General.FontSize
-1
General.OptionsFileName
General.GraphicsFontSize
17
General.OptionsFileName
General.GraphicsHeight
600
General.SessionFileName
General.GraphicsPositionX
50
General.SessionFileName
General.GraphicsPositionY
50
General.SessionFileName
General.GraphicsWidth
600
General.SessionFileName
General.InitialModule
0
General.OptionsFileName
General.Light0
1
General.OptionsFileName
General.Light0X
0.65
General.OptionsFileName
General.Light0Y
0.65
General.OptionsFileName
General.Light0Z
1
General.OptionsFileName
General.Light0W
0
General.OptionsFileName
General.Light1
0
General.OptionsFileName
General.Light1X
0.5
General.OptionsFileName
General.Light1Y
0.3
General.OptionsFileName
General.Light1Z
1
General.OptionsFileName
General.Light1W
0
General.OptionsFileName
General.Light2
0
General.OptionsFileName
General.Light2X
0.5
General.OptionsFileName
General.Light2Y
0.3
General.OptionsFileName
General.Light2Z
1
General.OptionsFileName
General.Light2W
0
General.OptionsFileName
General.Light3
0
General.OptionsFileName
General.Light3X
0.5
General.OptionsFileName
General.Light3Y
0.3
General.OptionsFileName
General.Light3Z
1
General.OptionsFileName
General.Light3W
0
General.OptionsFileName
General.Light4
0
General.OptionsFileName
General.Light4X
0.5
General.OptionsFileName
General.Light4Y
0.3
General.OptionsFileName
General.Light4Z
1
General.OptionsFileName
General.Light4W
0
General.OptionsFileName
General.Light5
0
General.OptionsFileName
General.Light5X
0.5
General.OptionsFileName
General.Light5Y
0.3
General.OptionsFileName
General.Light5Z
1
General.OptionsFileName
General.Light5W
0
General.OptionsFileName
General.LineWidth
1
General.OptionsFileName
General.ManipulatorPositionX
650
General.SessionFileName
General.ManipulatorPositionY
150
General.SessionFileName
General.MaxX
1
-
General.MaxY
1
-
General.MaxZ
1
-
General.MenuPositionX
800
General.SessionFileName
General.MenuPositionY
50
General.SessionFileName
General.MessagePositionX
650
General.SessionFileName
General.MessagePositionY
490
General.SessionFileName
General.MessageHeight
300
General.SessionFileName
General.MessageWidth
400
General.SessionFileName
General.MinX
0
-
General.MinY
0
-
General.MinZ
0
-
General.MouseHoverMeshes
0
General.OptionsFileName
General.MouseSelection
1
General.OptionsFileName
General.NonModalWindows
1
General.SessionFileName
General.NoPopup
0
General.OptionsFileName
General.OptionsPositionX
650
General.SessionFileName
General.OptionsPositionY
150
General.SessionFileName
General.Orthographic
1
General.OptionsFileName
General.PluginPositionX
650
General.SessionFileName
General.PluginPositionY
550
General.SessionFileName
General.PluginHeight
300
General.SessionFileName
General.PluginWidth
300
General.SessionFileName
General.PointSize
3
General.OptionsFileName
General.PolygonOffsetAlwaysOn
0
General.OptionsFileName
General.PolygonOffsetFactor
0.5
General.OptionsFileName
General.PolygonOffsetUnits
1
General.OptionsFileName
General.QuadricSubdivisions
8
General.OptionsFileName
General.RotationX
0
-
General.RotationY
0
-
General.RotationZ
0
-
General.RotationCenterGravity
1
General.OptionsFileName
General.RotationCenterX
0
-
General.RotationCenterY
0
-
General.RotationCenterZ
0
-
General.SaveOptions
0
General.SessionFileName
General.SaveSession
1
General.SessionFileName
General.ScaleX
1
-
General.ScaleY
1
-
General.ScaleZ
1
-
General.Shininess
0.4
General.OptionsFileName
General.ShininessExponent
40
General.OptionsFileName
General.SmallAxes
1
General.OptionsFileName
General.SmallAxesPositionX
-60
General.OptionsFileName
General.SmallAxesPositionY
-40
General.OptionsFileName
General.SmallAxesSize
30
General.OptionsFileName
General.SolverPositionX
650
General.SessionFileName
General.SolverPositionY
150
General.SessionFileName
General.StatisticsPositionX
650
General.SessionFileName
General.StatisticsPositionY
150
General.SessionFileName
General.SystemMenuBar
1
General.SessionFileName
General.Terminal
0
General.OptionsFileName
General.Tooltips
1
General.OptionsFileName
General.Trackball
1
General.OptionsFileName
General.TrackballQuaternion0
0
-
General.TrackballQuaternion1
0
-
General.TrackballQuaternion2
0
-
General.TrackballQuaternion3
1
-
General.TranslationX
0
-
General.TranslationY
0
-
General.TranslationZ
0
-
General.VectorType
4
General.OptionsFileName
General.Verbosity
3
General.OptionsFileName
General.VisibilityPositionX
650
General.SessionFileName
General.VisibilityPositionY
150
General.SessionFileName
General.ZoomFactor
4
General.OptionsFileName
General.Color.Background
{255,255,255}
General.OptionsFileName
General.Color.BackgroundGradient
{128,147,255}
General.OptionsFileName
General.Color.Foreground
{85,85,85}
General.OptionsFileName
General.Color.Text
{0,0,0}
General.OptionsFileName
General.Color.Axes
{0,0,0}
General.OptionsFileName
General.Color.SmallAxes
{0,0,0}
General.OptionsFileName
General.Color.AmbientLight
{25,25,25}
General.OptionsFileName
General.Color.DiffuseLight
{255,255,255}
General.OptionsFileName
General.Color.SpecularLight
{255,255,255}
General.OptionsFileName
Print.EpsBackground
1
General.OptionsFileName
Print.EpsBestRoot
1
General.OptionsFileName
Print.EpsCompress
0
General.OptionsFileName
Print.EpsLineWidthFactor
0.5
General.OptionsFileName
Print.EpsOcclusionCulling
1
General.OptionsFileName
Print.EpsPointSizeFactor
1
General.OptionsFileName
Print.EpsPS3Shading
0
General.OptionsFileName
Print.EpsQuality
1
General.OptionsFileName
Print.Format
10
General.OptionsFileName
Print.GeoLabels
1
General.OptionsFileName
Print.GifDither
0
General.OptionsFileName
Print.GifInterlace
0
General.OptionsFileName
Print.GifSort
1
General.OptionsFileName
Print.GifTransparent
0
General.OptionsFileName
Print.JpegQuality
100
General.OptionsFileName
Print.JpegSmoothing
0
General.OptionsFileName
Print.PostElementary
1
General.OptionsFileName
Print.PostElement
0
General.OptionsFileName
Print.PostGamma
0
General.OptionsFileName
Print.PostEta
0
General.OptionsFileName
Print.PostRho
0
General.OptionsFileName
Print.TexAsEquation
0
General.OptionsFileName
Print.Text
1
General.OptionsFileName
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Gmsh's geometry module provides a simple CAD engine, using a bottom-up
(boundary representation) approach: you need to first define points (using
the Point
command: see below), then lines (using Line
,
Circle
, Spline
, ..., commands or by extruding points),
then surfaces (using for example the Plane Surface
or Ruled
Surface
commands, or by extruding lines), and finally volumes (using the
Volume
command or by extruding surfaces).
These geometrical entities are called "elementary" in Gmsh's jargon, and are assigned identification numbers when they are created:
Elementary geometrical entities can then be manipulated in various
ways, for example using the Translate
, Rotate
, Scale
or
Symmetry
commands.
Compound groups of elementary geometrical entities can also be defined and are called "physical" entities. These physical entities cannot be modified by geometry commands: their only purpose is to assemble elementary entities into larger groups, possibly modifying their orientation, so that they can be referred to by the mesh module as single entities. As is the case with elementary entities, each physical point, physical line, physical surface or physical volume must be assigned a unique identification number. See 4. Mesh module, for more information about how physical entities affect the way meshes are saved.
3.1 Geometry commands 3.2 Geometry options
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The next subsections describe all the available geometry commands. These commands can be used anywhere in a Gmsh ASCII text input file. Note that the following general syntax rule is followed for the definition of geometrical entities: "If an expression defines a new entity, it is enclosed between parentheses. If an expression refers to a previously defined entity, it is enclosed between braces."
3.1.1 Points 3.1.2 Lines 3.1.3 Surfaces 3.1.4 Volumes 3.1.5 Extrusions 3.1.6 Transformations 3.1.7 Miscellaneous
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Point ( expression ) = { expression, expression, expression, expression };
Physical Point ( expression | char-expression ) = { expression-list };
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BSpline ( expression ) = { expression-list };
Circle ( expression ) = { expression, expression, expression };
CatmullRom ( expression ) = { expression-list };
CatmullRom
is a synonym for Spline
.
Ellipse ( expression ) = { expression, expression, expression, expression };
(A deprecated synonym for Ellipse
is Ellipsis
.)
Line ( expression ) = { expression, expression };
Spline ( expression ) = { expression-list };
Line Loop ( expression ) = { expression-list };
Line Loop
command. (Line loops are used to
create surfaces: see 3.1.3 Surfaces.)
Physical Line ( expression | char-expression ) = { expression-list };
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Plane Surface ( expression ) = { expression-list };
Ruled Surface ( expression ) = { expression-list } < In Sphere { expression } >;
In Sphere
argument forces the surface to be a
spherical patch (the extra parameter gives the identification number of
the center of the sphere).
Surface Loop ( expression ) = { expression-list };
Physical Surface ( expression | char-expression ) = { expression-list };
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Volume ( expression ) = { expression-list };
(A deprecated synonym for Volume
is Complex Volume
.)
Physical Volume ( expression | char-expression ) = { expression-list };
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Lines, surfaces and volumes can also be created through extrusion of points, lines and surfaces, respectively. Here is the syntax of the geometrical extrusion commands (go to 4.2.2 Structured grids, to see how these commands can be extended in order to also extrude the mesh):
extrude:
Extrude { expression-list } { extrude-list }
Extrude { { expression-list }, { expression-list }, expression } { extrude-list }
Extrude { { expression-list }, { expression-list }, { expression-list }, expression } { extrude-list }
with
extrude-list: Point | Line | Surface { expression-list }; ... |
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Geometrical transformations can be applied to elementary entities, or to
copies of elementary entities (using the Duplicata
command: see
below). The syntax of the transformation commands is:
transform:
Dilate { { expression-list }, expression } { transform-list }
Rotate { { expression-list }, { expression-list }, expression } { transform-list }
Symmetry { expression-list } { transform-list }
Translate { expression-list } { transform-list }
Boundary { transform-list }
with
transform-list: Point | Line | Surface { expression-list }; ... | Duplicata { Point | Line | Surface { expression-list }; ... } | transform |
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Here is a list of all other geometry commands currently available:
Coherence;
Coherence
command
automatically after each geometrical transformation, unless
Geometry.AutoCoherence
is set to zero (see section 3.2 Geometry options).
Delete { Point | Line | Surface | Volume { expression-list }; ... }
Hide { Point | Line | Surface | Volume { expression-list }; ... }
General.VisibilityMode
is set to 0
or 1
.
Hide char-expression;
General.VisibilityMode
is
set to 0
or 1
(char-expression can for example be
"*"
).
Show { Point | Line | Surface | Volume { expression-list }; ... }
General.VisibilityMode
is set to 0
or 1
.
Show char-expression;
General.VisibilityMode
is
set to 0
or 1
(char-expression can for example be
"*"
).
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
Geometry options control the behavior of geometry commands, as well as the way geometrical entities are handled in the graphical user interface. For the signification of the `Saved in:' field in the following list, see 2.7 General options.
Geometry.AutoCoherence
1
General.OptionsFileName
Geometry.CirclePoints
20
General.OptionsFileName
Geometry.ExtrudeReturnLateralEntities
1
General.OptionsFileName
Geometry.ExtrudeSplinePoints
5
General.OptionsFileName
Geometry.HighlightOrphans
0
General.OptionsFileName
Geometry.Light
1
General.OptionsFileName
Geometry.LightTwoSide
1
General.OptionsFileName
Geometry.Lines
1
General.OptionsFileName
Geometry.LineNumbers
0
General.OptionsFileName
Geometry.LineSelectWidth
2
General.OptionsFileName
Geometry.LineType
0
General.OptionsFileName
Geometry.LineWidth
2
General.OptionsFileName
Geometry.Normals
0
General.OptionsFileName
Geometry.OCCFixSmallEdges
1
General.OptionsFileName
Geometry.OCCFixSmallFaces
1
General.OptionsFileName
Geometry.OCCSewFaces
0
General.OptionsFileName
Geometry.OldCircle
0
General.OptionsFileName
Geometry.OldNewReg
1
General.OptionsFileName
Geometry.Points
1
General.OptionsFileName
Geometry.PointNumbers
0
General.OptionsFileName
Geometry.PointSelectSize
5
General.OptionsFileName
Geometry.PointSize
4
General.OptionsFileName
Geometry.PointType
0
General.OptionsFileName
Geometry.ScalingFactor
1
General.OptionsFileName
Geometry.SnapX
0.1
General.OptionsFileName
Geometry.SnapY
0.1
General.OptionsFileName
Geometry.SnapZ
0.1
General.OptionsFileName
Geometry.Surfaces
0
General.OptionsFileName
Geometry.SurfaceNumbers
0
General.OptionsFileName
Geometry.SurfaceType
2
General.OptionsFileName
Geometry.Tangents
0
General.OptionsFileName
Geometry.Tolerance
1e-06
General.OptionsFileName
Geometry.Volumes
0
General.OptionsFileName
Geometry.VolumeNumbers
0
General.OptionsFileName
Geometry.Color.Points
{90,90,90}
General.OptionsFileName
Geometry.Color.Lines
{0,0,255}
General.OptionsFileName
Geometry.Color.Surfaces
{128,128,128}
General.OptionsFileName
Geometry.Color.Volumes
{255,255,0}
General.OptionsFileName
Geometry.Color.Selection
{255,0,0}
General.OptionsFileName
Geometry.Color.HighlightZero
{255,0,0}
General.OptionsFileName
Geometry.Color.HighlightOne
{255,150,0}
General.OptionsFileName
Geometry.Color.HighlightTwo
{255,255,0}
General.OptionsFileName
Geometry.Color.Tangents
{255,255,0}
General.OptionsFileName
Geometry.Color.Normals
{255,0,0}
General.OptionsFileName
Geometry.Color.Projection
{0,255,0}
General.OptionsFileName
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Gmsh's mesh module regroups several 1D, 2D and 3D mesh algorithms, all producing grids conforming in the sense of finite elements (see section 1.2 Mesh: finite element mesh generation).
The 2D unstructured algorithms generate triangles or both triangles
and quadrangles (when Recombine Surface
is used: see
4.2.3 Miscellaneous). The 3D unstructured algorithms only
generate tetrahedra.
The 2D structured algorithms (transfinite and extrusion) generate
triangles by default, but quadrangles can be obtained by using the
Recombine
commands (see 4.2.2 Structured grids, and
4.2.3 Miscellaneous). The 3D structured algorithms
generate tetrahedra, hexahedra, prisms and pyramids, depending on the
type of the surface meshes they are based on.
4.1 Elementary vs. physical entities 4.2 Mesh commands 4.3 Mesh options
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If only elementary geometrical entities are defined (or if the
Mesh.SaveAll
option is set; see 4.3 Mesh options), the grid
produced by the mesh module will be saved "as is". That is, all the
elements in the grid will be saved to disk using the identification
number of the elementary entities they discretize as their elementary
region number (and 0 as their physical region number(6); 9. File formats). This can sometimes be inconvenient:
To remedy these problems, the geometry module (see section 3. Geometry module) introduces the notion of "physical" entities (also called "physical groups"). The purpose of physical entities is to assemble elementary entities into larger, possibly overlapping groups, and to control the orientation of the elements in these groups. The introduction of physical entities in large models usually greatly facilitates the manipulation of the model (e.g., using `Tools->Visibility' in the GUI) and the interfacing with external solvers.
In the MSH file format (see section 9. File formats), if physical entities are defined, the output mesh only contains those elements that belong to physical entities. Other file formats each treat physical entities in slightly different ways, depending on their capability to define groups.
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The mesh module commands mostly permit to modify the characteristic lengths and specify structured grid parameters. The actual mesh "actions" (i.e., "mesh the lines", "mesh the surfaces" and "mesh the volumes") cannot be specified in the input ASCII text input files. They have to be given either in the GUI or on the command line (see 8. Running Gmsh, and 8.3 Command-line options).
4.2.1 Characteristic lengths 4.2.2 Structured grids 4.2.3 Miscellaneous
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There are two ways to specify the size of the mesh elements for a given geometry:
Point
command: see 3.1.1 Points). The size of the
mesh elements will then be computed by linearly interpolating these
characteristic lengths on the initial mesh (see 1.2 Mesh: finite element mesh generation). This might
sometimes lead to over-refinement in some areas, so that you may have to
add "dummy" geometrical entities in the model in order to get the
desired element sizes.
This method works with all the algorithms implemented in the mesh module. The final element sizes are of course constrained by the structured algorithms for which the element sizes are explicitly specified (e.g., transfinite and extruded grids: see 4.2.2 Structured grids).
PostView
field specifies an explicit background mesh in the
form of a scalar post-processing view (see 6.1 Post-processing commands, and 9. File formats) in which the nodal values are the
target element sizes. This method is very general but it requires a
first (usually rough) mesh and a way to compute the target sizes on this
mesh (usually through an error estimation procedure, in an iterative
process of mesh adaptation).
(Note that you can also load a background mesh directly from the command
line using the -bgm
option (see section 8.3 Command-line options), or in
the GUI by selecting `Apply as background mesh' in the post-processing
view option menu.)
Box
field specifies the size of the elements inside and outside
of a parallelipipedic region.
Threshold
field specifies the size of the mesh according to the
distance to some geometrical entities. These entities can for example be
geometry points and lines specified by an Attractor
field.
MathEval
field specifies the size of the mesh using an explicit
mathematical function.
Min
field specifies the size as the minimum of the sizes
computed using other fields
Mesh.ConstrainedBackgroundMesh
option is set.
Fields are supported by all the algorithms except those based on Netgen.
Here are the mesh commands that are related to the specification of characteristic lengths:
Characteristic Length { expression-list } = expression;
Field[expression] = string;
Field[expression].string = char-expression | expression | expression-list;
Background Field = expression;
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Extrude { expression-list } { extrude-list layers }
layers: Layers { expression } | Layers { { expression-list }, { expression-list } } | Recombine; ... |
In the first Layers
form, expression gives the number of
elements to be created in the (single) layer. In the second form, the
first expression-list defines how many elements should be created
in each extruded layer, and the second expression-list gives the
normalized height of each layer (the list should contain a sequence of
n numbers 0 < h1 < h2 < ... < hn <= 1). See
7.3 `t3.geo', for an example.
For line extrusions, the Recombine
option will recombine triangles
into quadrangles when possible. For surface extrusions, the
Recombine
option will recombine tetrahedra into prisms, hexahedra or
pyramids.
Please note that, starting with Gmsh 2.0, region numbers cannot be
specified explicitly anymore in Layers
commands. Instead, as with
all other geometry commands, you must use the automatically created
entity identifier created by the extrusion command. For example, the
following extrusion command will return the id of the new "top"
surface in num[0]
and the id of the new volume in num[1]
:
num[] = Extrude {0,0,1} { Surface{1}; Layers{10}; }; |
Extrude { { expression-list }, { expression-list }, expression } { extrude-list layers }
Extrude { { expression-list }, { expression-list }, { expression-list }, expression } { extrude-list layers }
Extrude { Surface { expression-list }; layers }
Transfinite Line { expression-list } = expression < Using Progression | Bump expression >;
Using Progression expression
' instructs the
transfinite algorithm to distribute the nodes following a geometric
progression (Progression 2
meaning for example that each line element
in the series will be twice as long as the preceding one). The optional
argument `Using Bump expression
' instructs the transfinite
algorithm to distribute the nodes with a refinement at both ends of the
line.
(A deprecated synonym for Progression
is Power
.)
Transfinite Surface { expression } = { expression-list } < Left | Right | Alternate > ;
Transfinite Volume { expression } = { expression-list };
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Here is a list of all other mesh commands currently available:
Color color-expression { Point | Line | Surface | Volume { expression-list }; ... }
Hide { Point | Line | Surface | Volume { expression-list }; ... }
General.VisibilityMode
is set to 0
or 2
.
Hide char-expression;
General.VisibilityMode
is set to 0
or 2
(char-expression can for example be "*"
).
Recombine Surface { expression-list } < = expression >;
Save char-expression;
Mesh.Format
(see section 4.3 Mesh options). If the path in
char-expression is not absolute, char-expression is appended to
the path of the current file.
Show { Point | Line | Surface | Volume { expression-list }; ... }
General.VisibilityMode
is set to 0
or 2
.
Show char-expression;
General.VisibilityMode
is set to 0
or 2
(char-expression can for example be "*"
).
Smoother Surface { expression-list } = expression;
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
Mesh options control the behavior of mesh commands, as well as the way meshes are displayed in the graphical user interface. For the signification of the `Saved in:' field in the following list, see 2.7 General options.
Mesh.Algorithm
1
General.OptionsFileName
Mesh.Algorithm3D
1
General.OptionsFileName
Mesh.AngleSmoothNormals
30
General.OptionsFileName
Mesh.AllowSwapAngle
10
General.OptionsFileName
Mesh.BdfFieldFormat
1
General.OptionsFileName
Mesh.C1Continuity
0
General.OptionsFileName
Mesh.CharacteristicLengthExtendFromBoundary
1
General.OptionsFileName
Mesh.CharacteristicLengthFactor
1
General.OptionsFileName
Mesh.CharacteristicLengthMin
0
General.OptionsFileName
Mesh.CharacteristicLengthMax
1e+22
General.OptionsFileName
Mesh.CharacteristicLengthFromCurvature
0
General.OptionsFileName
Mesh.CharacteristicLengthFromPoints
1
General.OptionsFileName
Mesh.ColorCarousel
1
General.OptionsFileName
Mesh.CpuTime
0
-
Mesh.DrawSkinOnly
0
General.OptionsFileName
Mesh.Dual
0
General.OptionsFileName
Mesh.ElementOrder
1
General.OptionsFileName
Mesh.Explode
1
General.OptionsFileName
Mesh.Format
1
General.OptionsFileName
Mesh.Hexahedra
1
General.OptionsFileName
Mesh.LabelsFrequency
100
General.OptionsFileName
Mesh.LabelType
0
General.OptionsFileName
Mesh.Light
1
General.OptionsFileName
Mesh.LightLines
1
General.OptionsFileName
Mesh.LightTwoSide
1
General.OptionsFileName
Mesh.Lines
0
General.OptionsFileName
Mesh.LineNumbers
0
General.OptionsFileName
Mesh.LineWidth
1
General.OptionsFileName
Mesh.MinimumCirclePoints
7
General.OptionsFileName
Mesh.MinimumCurvePoints
3
General.OptionsFileName
Mesh.MshBinary
0
General.OptionsFileName
Mesh.MshFileVersion
2
General.OptionsFileName
Mesh.NbHexahedra
0
-
Mesh.NbNodes
0
-
Mesh.NbPrisms
0
-
Mesh.NbPyramids
0
-
Mesh.NbQuadrangles
0
-
Mesh.NbTetrahedra
0
-
Mesh.NbTriangles
0
-
Mesh.Normals
0
General.OptionsFileName
Mesh.Optimize
0
General.OptionsFileName
Mesh.OptimizeNetgen
0
General.OptionsFileName
Mesh.Points
0
General.OptionsFileName
Mesh.PointNumbers
0
General.OptionsFileName
Mesh.PointSize
4
General.OptionsFileName
Mesh.PointType
0
General.OptionsFileName
Mesh.Prisms
1
General.OptionsFileName
Mesh.Pyramids
1
General.OptionsFileName
Mesh.Quadrangles
1
General.OptionsFileName
Mesh.QualityInf
0
General.OptionsFileName
Mesh.QualitySup
0
General.OptionsFileName
Mesh.QualityType
2
General.OptionsFileName
Mesh.RadiusInf
0
General.OptionsFileName
Mesh.RadiusSup
0
General.OptionsFileName
Mesh.RandomFactor
1e-09
General.OptionsFileName
Mesh.RefineSteps
10
General.OptionsFileName
Mesh.RecombineAlgo
1
General.OptionsFileName
Mesh.ReverseAllNormals
0
General.OptionsFileName
Mesh.SaveAll
0
-
Mesh.SaveGroupsOfNodes
0
-
Mesh.ScalingFactor
1
General.OptionsFileName
Mesh.SecondOrderExperimental
0
General.OptionsFileName
Mesh.SecondOrderIncomplete
1
General.OptionsFileName
Mesh.SecondOrderLinear
0
General.OptionsFileName
Mesh.LcIntegrationPrecision
1e-09
General.OptionsFileName
Mesh.Smoothing
1
General.OptionsFileName
Mesh.SmoothInternalEdges
0
General.OptionsFileName
Mesh.SmoothNormals
0
General.OptionsFileName
Mesh.StlBinary
0
General.OptionsFileName
Mesh.SurfaceEdges
1
General.OptionsFileName
Mesh.SurfaceFaces
0
General.OptionsFileName
Mesh.SurfaceNumbers
0
General.OptionsFileName
Mesh.Tangents
0
General.OptionsFileName
Mesh.Tetrahedra
1
General.OptionsFileName
Mesh.Triangles
1
General.OptionsFileName
Mesh.VolumeEdges
1
General.OptionsFileName
Mesh.VolumeFaces
0
General.OptionsFileName
Mesh.VolumeNumbers
0
General.OptionsFileName
Mesh.Color.Points
{0,0,255}
General.OptionsFileName
Mesh.Color.PointsSup
{255,0,255}
General.OptionsFileName
Mesh.Color.Lines
{0,0,0}
General.OptionsFileName
Mesh.Color.Triangles
{160,150,255}
General.OptionsFileName
Mesh.Color.Quadrangles
{130,120,225}
General.OptionsFileName
Mesh.Color.Tetrahedra
{160,150,255}
General.OptionsFileName
Mesh.Color.Hexahedra
{130,120,225}
General.OptionsFileName
Mesh.Color.Prisms
{232,210,23}
General.OptionsFileName
Mesh.Color.Pyramids
{217,113,38}
General.OptionsFileName
Mesh.Color.Tangents
{255,255,0}
General.OptionsFileName
Mesh.Color.Normals
{255,0,0}
General.OptionsFileName
Mesh.Color.Zero
{255,120,0}
General.OptionsFileName
Mesh.Color.One
{255,160,0}
General.OptionsFileName
Mesh.Color.Two
{255,200,0}
General.OptionsFileName
Mesh.Color.Three
{255,240,0}
General.OptionsFileName
Mesh.Color.Four
{228,255,0}
General.OptionsFileName
Mesh.Color.Five
{188,255,0}
General.OptionsFileName
Mesh.Color.Six
{148,255,0}
General.OptionsFileName
Mesh.Color.Seven
{108,255,0}
General.OptionsFileName
Mesh.Color.Eight
{68,255,0}
General.OptionsFileName
Mesh.Color.Nine
{0,255,52}
General.OptionsFileName
Mesh.Color.Ten
{0,255,132}
General.OptionsFileName
Mesh.Color.Eleven
{0,255,192}
General.OptionsFileName
Mesh.Color.Twelve
{0,216,255}
General.OptionsFileName
Mesh.Color.Thirteen
{0,176,255}
General.OptionsFileName
Mesh.Color.Fourteen
{0,116,255}
General.OptionsFileName
Mesh.Color.Fifteen
{0,76,255}
General.OptionsFileName
Mesh.Color.Sixteen
{24,0,255}
General.OptionsFileName
Mesh.Color.Seventeen
{84,0,255}
General.OptionsFileName
Mesh.Color.Eighteen
{104,0,255}
General.OptionsFileName
Mesh.Color.Nineteen
{184,0,255}
General.OptionsFileName
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Five external solvers can be interfaced simultaneously with Gmsh.
If you just want to start a solver from the solver module, with no further
interactions between the solver and Gmsh, just edit the options relative to
one of the five available solvers (e.g., Solver.Name0
,
Solver.Executable0
, ...; see 5.1 Solver options), and set the
corresponding "client-server" option to zero
(e.g., Solver.ClientServer0 = 0
). This doesn't require any
modification to be made to the solver.
If you want the solver to interact with Gmsh (for error messages, option
definitions, post-processing, etc.), you need to link your solver with the
`GmshClient.c' file and add the appropriate function calls inside your
program. You can then proceed as in the previous case, but this time you
should set the client-server option to 1 (e.g., Solver.ClientServer0 =
1
), so that Gmsh and the solver can communicate through a Unix socket. See
5.2 Solver example, for an example of how to interface a C++
solver. Bindings for solvers written in other languages (C, Perl and Python)
are available in the source distribution.
5.1 Solver options 5.2 Solver example
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Solver.SocketName
".gmshsock"
General.OptionsFileName
Solver.Name0
"GetDP"
General.OptionsFileName
Solver.Help0
"A General environment for the treatment of
Discrete Problems.
Copyright (C) 1997-2008
Patrick Dular and Christophe Geuzaine.
Visit http://www.geuz.org/getdp/ for more info"
General.OptionsFileName
Solver.Executable0
"getdp"
General.OptionsFileName
Solver.Extension0
".pro"
General.OptionsFileName
Solver.MeshName0
""
General.OptionsFileName
Solver.MeshCommand0
"-msh %s"
General.OptionsFileName
Solver.SocketCommand0
"-socket %s"
General.OptionsFileName
Solver.NameCommand0
"%s"
General.OptionsFileName
Solver.OptionCommand0
""
General.OptionsFileName
Solver.FirstOption0
"Resolution"
General.OptionsFileName
Solver.SecondOption0
"PostOperation"
General.OptionsFileName
Solver.ThirdOption0
""
General.OptionsFileName
Solver.FourthOption0
""
General.OptionsFileName
Solver.FifthOption0
""
General.OptionsFileName
Solver.FirstButton0
"Pre"
General.OptionsFileName
Solver.FirstButtonCommand0
"-pre %s"
General.OptionsFileName
Solver.SecondButton0
"Cal"
General.OptionsFileName
Solver.SecondButtonCommand0
"-cal"
General.OptionsFileName
Solver.ThirdButton0
"Pos"
General.OptionsFileName
Solver.ThirdButtonCommand0
"-pos %s"
General.OptionsFileName
Solver.FourthButton0
""
General.OptionsFileName
Solver.FourthButtonCommand0
""
General.OptionsFileName
Solver.FifthButton0
""
General.OptionsFileName
Solver.FifthButtonCommand0
""
General.OptionsFileName
Solver.Name1
""
General.OptionsFileName
Solver.Help1
""
General.OptionsFileName
Solver.Executable1
""
General.OptionsFileName
Solver.Extension1
""
General.OptionsFileName
Solver.MeshName1
""
General.OptionsFileName
Solver.MeshCommand1
""
General.OptionsFileName
Solver.SocketCommand1
"-socket %s"
General.OptionsFileName
Solver.NameCommand1
"%s"
General.OptionsFileName
Solver.OptionCommand1
""
General.OptionsFileName
Solver.FirstOption1
""
General.OptionsFileName
Solver.SecondOption1
""
General.OptionsFileName
Solver.ThirdOption1
""
General.OptionsFileName
Solver.FourthOption1
""
General.OptionsFileName
Solver.FifthOption1
""
General.OptionsFileName
Solver.FirstButton1
""
General.OptionsFileName
Solver.FirstButtonCommand1
""
General.OptionsFileName
Solver.SecondButton1
""
General.OptionsFileName
Solver.SecondButtonCommand1
""
General.OptionsFileName
Solver.ThirdButton1
""
General.OptionsFileName
Solver.ThirdButtonCommand1
""
General.OptionsFileName
Solver.FourthButton1
""
General.OptionsFileName
Solver.FourthButtonCommand1
""
General.OptionsFileName
Solver.FifthButton1
""
General.OptionsFileName
Solver.FifthButtonCommand1
""
General.OptionsFileName
Solver.Name2
""
General.OptionsFileName
Solver.Help2
""
General.OptionsFileName
Solver.Executable2
""
General.OptionsFileName
Solver.Extension2
""
General.OptionsFileName
Solver.MeshName2
""
General.OptionsFileName
Solver.MeshCommand2
""
General.OptionsFileName
Solver.SocketCommand2
"-socket %s"
General.OptionsFileName
Solver.NameCommand2
"%s"
General.OptionsFileName
Solver.OptionCommand2
""
General.OptionsFileName
Solver.FirstOption2
""
General.OptionsFileName
Solver.SecondOption2
""
General.OptionsFileName
Solver.ThirdOption2
""
General.OptionsFileName
Solver.FourthOption2
""
General.OptionsFileName
Solver.FifthOption2
""
General.OptionsFileName
Solver.FirstButton2
""
General.OptionsFileName
Solver.FirstButtonCommand2
""
General.OptionsFileName
Solver.SecondButton2
""
General.OptionsFileName
Solver.SecondButtonCommand2
""
General.OptionsFileName
Solver.ThirdButton2
""
General.OptionsFileName
Solver.ThirdButtonCommand2
""
General.OptionsFileName
Solver.FourthButton2
""
General.OptionsFileName
Solver.FourthButtonCommand2
""
General.OptionsFileName
Solver.FifthButton2
""
General.OptionsFileName
Solver.FifthButtonCommand2
""
General.OptionsFileName
Solver.Name3
""
General.OptionsFileName
Solver.Help3
""
General.OptionsFileName
Solver.Executable3
""
General.OptionsFileName
Solver.Extension3
""
General.OptionsFileName
Solver.MeshName3
""
General.OptionsFileName
Solver.MeshCommand3
""
General.OptionsFileName
Solver.SocketCommand3
"-socket %s"
General.OptionsFileName
Solver.NameCommand3
"%s"
General.OptionsFileName
Solver.OptionCommand3
""
General.OptionsFileName
Solver.FirstOption3
""
General.OptionsFileName
Solver.SecondOption3
""
General.OptionsFileName
Solver.ThirdOption3
""
General.OptionsFileName
Solver.FourthOption3
""
General.OptionsFileName
Solver.FifthOption3
""
General.OptionsFileName
Solver.FirstButton3
""
General.OptionsFileName
Solver.FirstButtonCommand3
""
General.OptionsFileName
Solver.SecondButton3
""
General.OptionsFileName
Solver.SecondButtonCommand3
""
General.OptionsFileName
Solver.ThirdButton3
""
General.OptionsFileName
Solver.ThirdButtonCommand3
""
General.OptionsFileName
Solver.FourthButton3
""
General.OptionsFileName
Solver.FourthButtonCommand3
""
General.OptionsFileName
Solver.FifthButton3
""
General.OptionsFileName
Solver.FifthButtonCommand3
""
General.OptionsFileName
Solver.Name4
""
General.OptionsFileName
Solver.Help4
""
General.OptionsFileName
Solver.Executable4
""
General.OptionsFileName
Solver.Extension4
""
General.OptionsFileName
Solver.MeshName4
""
General.OptionsFileName
Solver.MeshCommand4
""
General.OptionsFileName
Solver.SocketCommand4
"-socket %s"
General.OptionsFileName
Solver.NameCommand4
"%s"
General.OptionsFileName
Solver.OptionCommand4
""
General.OptionsFileName
Solver.FirstOption4
""
General.OptionsFileName
Solver.SecondOption4
""
General.OptionsFileName
Solver.ThirdOption4
""
General.OptionsFileName
Solver.FourthOption4
""
General.OptionsFileName
Solver.FifthOption4
""
General.OptionsFileName
Solver.FirstButton4
""
General.OptionsFileName
Solver.FirstButtonCommand4
""
General.OptionsFileName
Solver.SecondButton4
""
General.OptionsFileName
Solver.SecondButtonCommand4
""
General.OptionsFileName
Solver.ThirdButton4
""
General.OptionsFileName
Solver.ThirdButtonCommand4
""
General.OptionsFileName
Solver.FourthButton4
""
General.OptionsFileName
Solver.FourthButtonCommand4
""
General.OptionsFileName
Solver.FifthButton4
""
General.OptionsFileName
Solver.FifthButtonCommand4
""
General.OptionsFileName
Solver.AlwaysListen
0
General.OptionsFileName
Solver.ClientServer0
1
General.OptionsFileName
Solver.ClientServer1
0
General.OptionsFileName
Solver.ClientServer2
0
General.OptionsFileName
Solver.ClientServer3
0
General.OptionsFileName
Solver.ClientServer4
0
General.OptionsFileName
Solver.MaximumDelay
4
General.OptionsFileName
Solver.MergeViews0
1
General.OptionsFileName
Solver.MergeViews1
1
General.OptionsFileName
Solver.MergeViews2
1
General.OptionsFileName
Solver.MergeViews3
1
General.OptionsFileName
Solver.MergeViews4
1
General.OptionsFileName
Solver.Plugins
0
General.OptionsFileName
Solver.PopupMessages0
1
General.OptionsFileName
Solver.PopupMessages1
1
General.OptionsFileName
Solver.PopupMessages2
1
General.OptionsFileName
Solver.PopupMessages3
1
General.OptionsFileName
Solver.PopupMessages4
1
General.OptionsFileName
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Here is a small example of how to interface a C++ solver with Gmsh. The following listing reproduces the `utils/solvers/c++/solver.cpp' file from the Gmsh source distribution (C, Perl and Python examples are also available).
// $Id: solver.cpp,v 1.10 2007-09-04 13:47:08 remacle Exp $ // // Copyright (C) 1997-2005 C. Geuzaine, J.-F. Remacle // // Permission is hereby granted, free of charge, to any person // obtaining a copy of this software and associated documentation // files (the "Software"), to deal in the Software without // restriction, including without limitation the rights to use, copy, // modify, merge, publish, distribute, and/or sell copies of the // Software, and to permit persons to whom the Software is furnished // to do so, provided that the above copyright notice(s) and this // permission notice appear in all copies of the Software and that // both the above copyright notice(s) and this permission notice // appear in supporting documentation. // // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND // NONINFRINGEMENT OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE // COPYRIGHT HOLDER OR HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR // ANY CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY // DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, // WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS // ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE // OF THIS SOFTWARE. // // Please report all bugs and problems to <gmsh@geuz.org>. // This file contains a dummy client solver for Gmsh. It does not // solve anything, but shows how to program your own solver to interact // with the Gmsh solver module. // // To compile this solver, type something like: // // g++ solver.cpp -o solver.exe // // To run it, merge the contents of the file solver.opt into your // default Gmsh option file, or launch Gmsh with the command: // // gmsh -option solver.opt // // You will then see a new button labeled "My C++ solver" in Gmsh's // solver menu. #include <math.h> #include "GmshClient.h" typedef enum { send_options, run_code } action; int main(int argc, char *argv[]) { action what_to_do = run_code; char *name = NULL, *option = NULL, *socket = NULL; // parse command line int i = 0; while(i < argc) { if(argv[i][0] == '-') { if(!strcmp(argv[i] + 1, "socket")) { i++; if(argv[i]) socket = argv[i++]; } else if(!strcmp(argv[i] + 1, "options")) { i++; what_to_do = send_options; } else if(!strcmp(argv[i] + 1, "run")) { i++; what_to_do = run_code; if(argv[i]) option = argv[i++]; } } else name = argv[i++]; } if(!socket) { printf("No socket specified: running non-interactively...\n"); exit(1); } // connect to Gmsh GmshClient client; if(client.Connect(socket) < 0){ printf("Unable to connect to Gmsh\n"); exit(1); } client.Start(); if(what_to_do == send_options) { // send the available options for this computation client.Option(1, "FormulationH"); client.Option(1, "ConvTest"); client.Option(1, "Blablabli"); } else if(what_to_do == run_code){ // do the computation and merge some views for(int i = 0; i < 10; i++){ client.Info("Computing curve..."); // fake computation for 500ms: #if !defined(WIN32) || defined(__CYGWIN__) usleep(500 * 1000); #else Sleep(500); #endif client.Info("Done computing curve"); FILE *file = fopen("solver.pos", "w"); if(!file) client.Error("Unable to open output file"); else { fprintf(file, "View.Type = 2;\n"); fprintf(file, "View.Axes = 3;\n"); fprintf(file, "Delete View[0];\n"); fprintf(file, "View \"%s\"{\n", option); for(int j = 0; j < 100; j++) fprintf(file, "SP(%d,0,0){%g};\n", j,sin(j*i*M_PI/10.)); fprintf(file, "};\n"); fclose(file); client.MergeFile("solver.pos"); } } client.Info("Done!"); } client.Stop(); client.Disconnect(); }
To define the above solver as the second external solver in Gmsh, you then
need to define the following options (either merge them in your Gmsh option
file, or use the -option
command-line option--see 8.3 Command-line options):
Solver.Name1 = "My C++ Solver"; Solver.Executable1 = "solver.exe"; Solver.OptionCommand1 = "-options"; Solver.FirstOption1 = "My options"; Solver.FirstButton1 = "Run !"; Solver.FirstButtonCommand1 = "-run %s"; Solver.ClientServer1 = 1; Solver.MergeViews1 = 1; Solver.PopupMessages1 = 1;
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
Gmsh's post-processing module can handle multiple scalar, vector or tensor
data sets along with the geometry and the mesh. The data sets should be
given in one of Gmsh's post-processing file formats described in 9. File formats. Once loaded into Gmsh, scalar fields can be displayed as iso-value
lines and surfaces or color maps, whereas vector fields can be represented
either by three-dimensional arrows or by displacement maps. (Tensor fields
are currently displayed as Von-Mises effective stresses. To display other
(combinations of) components, use Plugin(Extract)
: see
6.2 Post-processing plugins.)
In Gmsh's jargon, each data set is called a "view", and can arbitrarily
mix all types of elements and fields. Each view is given a name, and can be
manipulated either individually (each view has its own button in the GUI and
can be referred to by its index in a script) or globally (see the
PostProcessing.Link
option in 6.3 Post-processing options).
By default, Gmsh treats all post-processing views as three-dimensional plots, i.e., draws the scalar, vector and tensor primitives (points, lines, triangles, tetrahedra, etc.) in 3D space. But Gmsh can also represent each post-processing view containing scalar points as two-dimensional ("X-Y") plots, either space- or time-oriented:
Although visualization is usually mostly an interactive task, Gmsh exposes all the post-processing commands and options to the user in its scripting language to permit a complete automation of the post-processing process (see e.g., 7.8 `t8.geo', and 7.9 `t9.geo').
The two following sections summarize all available post-processing commands and options. Most options apply to both 2D and 3D plots (colormaps, point/line sizes, interval types, time step selection, etc.), but some are peculiar to 3D (lightning, element selection, etc.) or 2D plots (abscissa labels, etc.). Note that 2D plots can be positioned explicitly inside the graphical window, or be automatically positioned in order to avoid overlaps.
Sample post-processing files in human-readable "parsed" format are available in the `tutorial' directory of Gmsh's distribution (`.pos' files).
6.1 Post-processing commands 6.2 Post-processing plugins 6.3 Post-processing options
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Alias View[expression];
Note that Alias
creates a logical duplicate of the view without
actually duplicating the data in memory. This is very useful when you want
multiple simultaneous renderings of the same large dataset (usually with
different display options), but you cannot afford to store all copies in
memory. If what you really want is multiple physical copies of the data,
just merge the file containing the post-processing view multiple times.
AliasWithOptions View[expression];
Combine ElementsByViewName;
Combine ElementsFromAllViews | Combine Views;
Combine ElementsFromVisibleViews;
Combine TimeStepsByViewName | Combine TimeSteps;
Combine TimeStepsFromAllViews;
Combine TimeStepsFromVisibleViews;
Delete View[expression];
Delete Empty Views;
Background Mesh View[expression];
Plugin (string) . Run;
Plugin (string) . string = expression | char-expression;
Save View[expression] char-expression;
View "string" { string < ( expression-list ) > { expression-list }; ... };
"string"
. This
is an easy and quite powerful way to import post-processing data: all
the values are expressions, you can embed datasets directly into
your geometrical descriptions (see, e.g., 7.4 `t4.geo'), the data can be
easily generated "on-the-fly" (there is no header containing a
priori information on the size of the dataset). The syntax is also very
permissive, which makes it ideal for testing purposes.
However this "parsed format" is read by Gmsh's script parser, which makes it inefficient if there are many elements in the dataset. Also, there is no connectivity information in parsed views and all the elements are independent (all fields can be discontinuous), so a lot of information can be duplicated. For large datasets, you should thus use the mesh-based post-processing file format described in 9. File formats, or use one of the standard formats like MED.
More explicitly, the syntax for a parsed View
is the following
View "string" { < TIME { expression-list }; > type ( list-of-coords ) { list-of-values }; ... }; |
where the 47 object types that can be displayed are:
type #list-of-coords #list-of-values -------------------------------------------------------------------- Scalar point SP 3 1 * nb-time-steps Vector point VP 3 3 * nb-time-steps Tensor point TP 3 9 * nb-time-steps Scalar line SL 6 2 * nb-time-steps Vector line VL 6 6 * nb-time-steps Tensor line TL 6 18 * nb-time-steps Scalar triangle ST 9 3 * nb-time-steps Vector triangle VT 9 9 * nb-time-steps Tensor triangle TT 9 27 * nb-time-steps Scalar quadrangle SQ 12 4 * nb-time-steps Vector quadrangle VQ 12 12 * nb-time-steps Tensor quadrangle TQ 12 36 * nb-time-steps Scalar tetrahedron SS 12 4 * nb-time-steps Vector tetrahedron VS 12 12 * nb-time-steps Tensor tetrahedron TS 12 36 * nb-time-steps Scalar hexahedron SH 24 8 * nb-time-steps Vector hexahedron VH 24 24 * nb-time-steps Tensor hexahedron TH 24 72 * nb-time-steps Scalar prism SI 18 6 * nb-time-steps Vector prism VI 18 18 * nb-time-steps Tensor prism TI 18 54 * nb-time-steps Scalar pyramid SY 15 5 * nb-time-steps Vector pyramid VY 15 15 * nb-time-steps Tensor pyramid TY 15 45 * nb-time-steps 2nd order scalar line SL2 9 3 * nb-time-steps 2nd order vector line VL2 9 9 * nb-time-steps 2nd order tensor line TL2 9 27 * nb-time-steps 2nd order scalar triangle ST2 18 6 * nb-time-steps 2nd order vector triangle VT2 18 18 * nb-time-steps 2nd order tensor triangle TT2 18 54 * nb-time-steps 2nd order scalar quadrangle SQ2 27 9 * nb-time-steps 2nd order vector quadrangle VQ2 27 27 * nb-time-steps 2nd order tensor quadrangle TQ2 27 81 * nb-time-steps 2nd order scalar tetrahedron SS2 30 10 * nb-time-steps 2nd order vector tetrahedron VS2 30 30 * nb-time-steps 2nd order tensor tetrahedron TS2 30 90 * nb-time-steps 2nd order scalar hexahedron SH2 81 27 * nb-time-steps 2nd order vector hexahedron VH2 81 81 * nb-time-steps 2nd order tensor hexahedron TH2 81 243* nb-time-steps 2nd order scalar prism SI2 54 18 * nb-time-steps 2nd order vector prism VI2 54 54 * nb-time-steps 2nd order tensor prism TI2 54 162* nb-time-steps 2nd order scalar pyramid SY2 42 14 * nb-time-steps 2nd order vector pyramid VY2 42 42 * nb-time-steps 2nd order tensor pyramid TY2 42 126* nb-time-steps 2D text T2 3 arbitrary 3D text T3 4 arbitrary |
The coordinates are given `by node', i.e.,
(coord1, coord2, coord3)
for a point,
(coord1-node1, coord2-node1, coord3-node1,
coord1-node2, coord2-node2, coord3-node2)
for a line,
(coord1-node1, coord2-node1, coord3-node1,
coord1-node2, coord2-node2, coord3-node2,
coord1-node3, coord2-node3, coord3-node3)
for a triangle,
The ordering of the nodes is given in 9.3 Node ordering.
The values are given by time step, by node and by component, i.e.:
comp1-node1-time1, comp2-node1-time1, comp3-node1-time1, comp1-node2-time1, comp2-node2-time1, comp3-node2-time1, comp1-node3-time1, comp2-node3-time1, comp3-node3-time1, comp1-node1-time2, comp2-node1-time2, comp3-node1-time2, comp1-node2-time2, comp2-node2-time2, comp3-node2-time2, comp1-node3-time2, comp2-node3-time2, comp3-node3-time2, ... |
For the 2D text objects, the two first expressions in list-of-coords give the X-Y position of the string in screen coordinates, measured from the top-left corner of the window. If the first (respectively second) expression is negative, the position is measured from the right (respectively bottom) edge of the window. If the value of the first (respectively second) expression is larger than 99999, the string is centered horizontally (respectively vertically). If the third expression is equal to zero, the text is aligned bottom-left and displayed using the default font and size. Otherwise, the third expression is converted into an integer whose eight lower bits give the font size, whose eight next bits select the font (the index corresponds to the position in the font menu in the GUI), and whose eight next bits define the text alignment (0=bottom-left, 1=bottom-center, 2=bottom-right, 3=top-left, 4=top-center, 5=top-right, 6=center-left, 7=center-center, 8=center-right).
For the 3D text objects, the three first expressions in list-of-coords give the XYZ position of the string in model (real world) coordinates. The fourth expression has the same meaning as the third expression in 2D text objects.
For both 2D and 3D text objects, the list-of-values can contain an arbitrary number of char-expressions.
The optional TIME
list can contain a list of expressions giving the
value of the time (or any other variable) for which an evolution was saved.
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
Post-processing plugins permit to extend the functionality of Gmsh's post-processing module. The difference between regular post-processing options (see section 6.3 Post-processing options) and post-processing plugins is that regular post-processing options only change the way the data is displayed, while post-processing plugins either create new post-processing views, or modify the data stored in a view (in a destructive, non-reversible way).
Plugins are available in the graphical user interface by right-clicking on a view button (or by clicking on the black arrow next to the view button) and then selecting the `Plugin' submenu.
Here is the list of the plugins that are shipped by default with Gmsh:
Plugin(Annotate)
Plugin(Annotate) is executed in-place.
String options:
Text
"My Text"
Font
"Helvetica"
Align
"Left"
X
50
Y
30
Z
0
ThereD
0
FontSize
14
iView
-1
Plugin(Curl)
Plugin(Curl) creates one new view.
Numeric options:
iView
-1
Plugin(CutGrid)
Plugin(CutGrid) creates one new view.
Numeric options:
X0
0
Y0
0
Z0
0
X1
1
Y1
0
Z1
0
X2
0
Y2
1
Z2
0
nPointsU
20
nPointsV
20
ConnectPoints
1
iView
-1
Plugin(CutMap)
Plugin(CutMap) creates as many views as there are time steps in `iView'.
Numeric options:
A
0
dTimeStep
-1
dView
-1
ExtractVolume
0
RecurLevel
4
TargetError
0
iView
-1
Plugin(CutParametric)
Plugin(CutParametric) creates one new view.
String options:
X
"0 + 1 * Cos(u)"
Y
"0 + 1 * Sin(u)"
Z
"0"
MinU
0
MaxU
6.2832
nPointsU
360
ConnectPoints
0
iView
-1
Plugin(CutPlane)
Plugin(CutPlane) creates one new view.
Numeric options:
A
1
B
0
C
0
D
-0.01
ExtractVolume
0
RecurLevel
4
TargetError
0
iView
-1
Plugin(CutSphere)
Plugin(CutSphere) creates one new view.
Numeric options:
Xc
0
Yc
0
Zc
0
R
0.25
ExtractVolume
0
RecurLevel
4
iView
-1
Plugin(Divergence)
Plugin(Divergence) creates one new view.
Numeric options:
iView
-1
Plugin(Eigenvalues)
Plugin(Eigenvalues) creates three new scalar views.
Numeric options:
iView
-1
Plugin(Eigenvectors)
Plugin(Eigenvectors) creates three new vector views.
Numeric options:
ScaleByEigenvalues
1
iView
-1
Plugin(Evaluate)
- the usual mathematical functions (Log, Sqrt, Sin, Cos, Fabs, ...) and operators (+, -, *, /, ^);
- the symbols x, y and z, to retrieve the coordinates of the current node;
- the symbols Time and TimeStep, to retrieve the current time and time step values;
- the symbol v, to retrieve the `Component'-th component of the field in `iView' at the `TimeStep'-th time step;
- the symbols v0, v1, v2, ..., v8, to retrieve each component of the field in `iView' at the `TimeStep'-th time step;
- the symbol w, to retrieve the `Component'-th component of the field in `ExternalView' at the `ExternalTimeStep'-th time step. If `ExternalView' and `iView' are based on different spatial grids, or if their data types are different, `ExternalView' is interpolated onto `iView';
- the symbols w0, w1, w2, ..., w8, to retrieve each component of the field in `ExternalView' at the `ExternalTimeStep'-th time step.
If `TimeStep' < 0, the plugin automatically loops over all the time steps in `iView' and evaluates `Expression' for each one. If `ExternalTimeStep' < 0, the plugin uses `TimeStep' instead. If `Component' < 0, the plugin automatically loops over all the components in the view and evaluates `Expression' for each one. If `iView' < 0, the plugin is run on the current view. If `ExternalView' < 0, the plugin uses `iView' instead.
Plugin(Evaluate) is executed in-place.
String options:
Expression
"v0*Sin(x)"
Component
-1
TimeStep
-1
ExternalView
-1
ExternalTimeStep
-1
iView
-1
Plugin(Extract)
Plugin(Extract) creates one new view.
String options:
Expression0
"Sqrt(v0^2+v1^2+v2^2)"
Expression1
""
Expression2
""
Expression3
""
Expression4
""
Expression5
""
Expression6
""
Expression7
""
Expression8
""
TimeStep
-1
iView
-1
Plugin(ExtractElements)
Plugin(ExtractElements) creates one new view.
Numeric options:
MinVal
0
MaxVal
1
TimeStep
0
iView
-1
Plugin(FieldView)
Numeric options:
Component
-1
iView
-1
iField
-1
Plugin(GSHHS)
String options:
InFileName
"gshhs_c.b"
OutFileName
"earth.geo"
Format
"gshhs"
Coordinate
"cartesian"
iField
-1
UTMZone
0
UTMEquatorialRadius
6.37814e+06
UTMPolarRadius
6.35675e+06
UTMScale
1
UTMShiftX
0
UTMShiftY
0
WritePolarSphere
1
Plugin(Gradient)
Plugin(Gradient) creates one new view.
Numeric options:
iView
-1
Plugin(HarmonicToTime)
Plugin(HarmonicToTime) creates one new view.
Numeric options:
RealPart
0
ImaginaryPart
1
nSteps
20
iView
-1
Plugin(Integrate)
Plugin(Integrate) creates one new view.
Numeric options:
iView
-1
Plugin(Lambda2)
Plugin(Lambda2) creates one new view.
Numeric options:
Eigenvalue
2
iView
-1
Plugin(MakeSimplex)
Plugin(MakeSimplex) is executed in-place.
Numeric options:
iView
-1
Plugin(ModulusPhase)
Plugin(ModulusPhase) is executed in-place.
Numeric options:
RealPart
0
ImaginaryPart
1
iView
-1
Plugin(Probe)
Plugin(Probe) creates one new view.
Numeric options:
X
0
Y
0
Z
0
iView
-1
Plugin(Remove)
Plugin(Remove) is executed in-place.
Numeric options:
Text2D
1
Text3D
1
Points
0
Lines
0
Triangles
0
Quadrangles
0
Tetrahedra
0
Hexahedra
0
Prisms
0
Pyramids
0
Scalar
1
Vector
1
Tensor
1
iView
-1
Plugin(Skin)
Plugin(Skin) creates one new view.
Numeric options:
iView
-1
Plugin(Smooth)
Plugin(Smooth) is executed in-place.
Numeric options:
iView
-1
Plugin(SphericalRaise)
Plugin(SphericalRaise) is executed in-place.
Numeric options:
Xc
0
Yc
0
Zc
0
Raise
1
Offset
0
TimeStep
0
iView
-1
Plugin(StreamLines)
Plugin(StreamLines) creates one new view. This view contains multi-step vector points if `dView' < 0, or single-step scalar lines if `dView' >= 0.
Numeric options:
X0
0
Y0
0
Z0
0
X1
1
Y1
0
Z1
0
X2
0
Y2
1
Z2
0
nPointsU
10
nPointsV
1
MaxIter
100
DT
0.1
TimeStep
0
dView
-1
iView
-1
Plugin(Transform)
Plugin(Transform) is executed in-place.
Numeric options:
A11
1
A12
0
A13
0
A21
0
A22
1
A23
0
A31
0
A32
0
A33
1
Tx
0
Ty
0
Tz
0
SwapOrientation
0
iView
-1
Plugin(TransformLatLon)
Plugin(TransformLatLon) is executed in-place.
Numeric options:
iView
-1
Longitude0
0
Plugin(Triangulate)
Plugin(Triangulate) creates one new view.
Numeric options:
iView
-1
Plugin(Warp)
Plugin(Warp) is executed in-place.
Numeric options:
Factor
1
TimeStep
0
SmoothingAngle
180
dView
-1
iView
-1
[ < ] | [ > ] | [ << ] | [ Up ] | [ >> ] | [Top] | [Contents] | [Index] | [ ? ] |
General post-processing option names have the form
`PostProcessing.string
'. Options peculiar to post-processing
views take two forms:
View.string
', before any view is loaded;
View[n].string
' (n = 0, 1, 2,
...), after the n-th view is loaded.
See 7.8 `t8.geo', and 7.9 `t9.geo', for some examples.
PostProcessing.AnimationDelay
0.25
General.OptionsFileName
PostProcessing.AnimationCycle
0
General.OptionsFileName
PostProcessing.CombineRemoveOriginal
1
General.OptionsFileName
PostProcessing.Format
0
General.OptionsFileName
PostProcessing.HorizontalScales
1
General.OptionsFileName
PostProcessing.Link
0
General.OptionsFileName
PostProcessing.NbViews
0
-
PostProcessing.Plugins
1
General.OptionsFileName
PostProcessing.Smoothing
0
General.OptionsFileName
View.AxesFormatX
"%.3g"
General.OptionsFileName
View.AxesFormatY
"%.3g"
General.OptionsFileName
View.AxesFormatZ
"%.3g"
General.OptionsFileName
View.AxesLabelX
""
General.OptionsFileName
View.AxesLabelY
""
General.OptionsFileName
View.AxesLabelZ
""
General.OptionsFileName
View.FileName
""
-
View.Format
"%.3g"
General.OptionsFileName
View.GeneralizedRaiseX
"v0"
General.OptionsFileName
View.GeneralizedRaiseY
"v1"
General.OptionsFileName
View.GeneralizedRaiseZ
"v2"
General.OptionsFileName
View.Name
""
-
View.Stipple0
"1*0x1F1F"
General.OptionsFileName
View.Stipple1
"1*0x3333"
General.OptionsFileName
View.Stipple2
"1*0x087F"
General.OptionsFileName
View.Stipple3
"1*0xCCCF"
General.OptionsFileName
View.Stipple4
"2*0x1111"
General.OptionsFileName
View.Stipple5
"2*0x0F0F"
General.OptionsFileName
View.Stipple6
"1*0xCFFF"
General.OptionsFileName
View.Stipple7
"2*0x0202"
General.OptionsFileName
View.Stipple8
"2*0x087F"
General.OptionsFileName
View.Stipple9
"1*0xFFFF"
General.OptionsFileName
View.AngleSmoothNormals
30
General.OptionsFileName
View.ArrowHeadRadius
0.12
General.OptionsFileName
View.ArrowSize
60
General.OptionsFileName
View.ArrowSizeProportional
1
General.OptionsFileName
View.ArrowStemLength
0.56
General.OptionsFileName
View.ArrowStemRadius
0.02
General.OptionsFileName
View.AutoPosition
1
General.OptionsFileName
View.Axes
0
General.OptionsFileName
View.AxesMikado
0
General.OptionsFileName
View.AxesAutoPosition
1
General.OptionsFileName
View.AxesMaxX
1
General.OptionsFileName
View.AxesMaxY
1
General.OptionsFileName
View.AxesMaxZ
1
General.OptionsFileName
View.AxesMinX
0
General.OptionsFileName
View.AxesMinY
0
General.OptionsFileName
View.AxesMinZ
0
General.OptionsFileName
View.AxesTicsX
5
General.OptionsFileName
View.AxesTicsY
5
General.OptionsFileName
View.AxesTicsZ
5
General.OptionsFileName
View.Boundary
0
General.OptionsFileName
View.CenterGlyphs
0
General.OptionsFileName
View.ColormapAlpha
1
General.OptionsFileName
View.ColormapAlphaPower
0
General.OptionsFileName
View.ColormapBeta
0
General.OptionsFileName
View.ColormapBias
0
General.OptionsFileName
View.ColormapCurvature
0
General.OptionsFileName
View.ColormapInvert
0
General.OptionsFileName
View.ColormapNumber
2
General.OptionsFileName
View.ColormapRotation
0
General.OptionsFileName
View.ColormapSwap
0
General.OptionsFileName
View.CustomMax
0
-
View.CustomMin
0
-
View.DisplacementFactor
1
General.OptionsFileName
View.DrawHexahedra
1
General.OptionsFileName
View.DrawLines
1
General.OptionsFileName
View.DrawPoints
1
General.OptionsFileName
View.DrawPrisms
1
General.OptionsFileName
View.DrawPyramids
1
General.OptionsFileName
View.DrawQuadrangles
1
General.OptionsFileName
View.DrawScalars
1
General.OptionsFileName
View.DrawSkinOnly
0
General.OptionsFileName
View.DrawStrings
1
General.OptionsFileName
View.DrawTensors
1
General.OptionsFileName
View.DrawTetrahedra
1
General.OptionsFileName
View.DrawTriangles
1
General.OptionsFileName
View.DrawVectors
1
General.OptionsFileName
View.Explode
1
General.OptionsFileName
View.ExternalView
-1
General.OptionsFileName
View.FakeTransparency
0
General.OptionsFileName
View.GeneralizedRaiseFactor
1
General.OptionsFileName
View.GeneralizedRaiseView
-1
General.OptionsFileName
View.GlyphLocation
1
General.OptionsFileName
View.Height
200
General.OptionsFileName
View.IntervalsType
2
General.OptionsFileName
View.Light
1
General.OptionsFileName
View.LightLines
1
General.OptionsFileName
View.LightTwoSide
1
General.OptionsFileName
View.LineType
0
General.OptionsFileName
View.LineWidth
1
General.OptionsFileName
View.MaxRecursionLevel
0
General.OptionsFileName
View.Max
0
-
View.MaxX
0
-
View.MaxY
0
-
View.MaxZ
0
-
View.Min
0
-
View.MinX
0
-
View.MinY
0
-
View.MinZ
0
-
View.NbIso
15
General.OptionsFileName
View.NbTimeStep
1
-
View.NormalRaise
0
-
View.Normals
0
General.OptionsFileName
View.OffsetX
0
-
View.OffsetY
0
-
View.OffsetZ
0
-
View.PointSize
3
General.OptionsFileName
View.PointType
0
General.OptionsFileName
View.PositionX
100
General.OptionsFileName
View.PositionY
50
General.OptionsFileName
View.RaiseX
0
-
View.RaiseY
0
-
View.RaiseZ
0
-
View.RangeType
1
General.OptionsFileName
View.SaturateValues
0
General.OptionsFileName
View.ScaleType
1
General.OptionsFileName
View.ShowElement
0
General.OptionsFileName
View.ShowScale
1
General.OptionsFileName
View.ShowTime
1
General.OptionsFileName
View.SmoothNormals
0
General.OptionsFileName
View.Stipple
0
General.OptionsFileName
View.Tangents
0
General.OptionsFileName
View.TargetError
0.01
General.OptionsFileName
View.TensorType
1
General.OptionsFileName
View.TimeStep
0
-
View.Transform11
1
-
View.Transform12
0
-
View.Transform13
0
-
View.Transform21
0
-
View.Transform22
1
-
View.Transform23
0
-
View.Transform31
0
-
View.Transform32
0
-
View.Transform33
1
-
View.Type
1
-
View.UseGeneralizedRaise
0
General.OptionsFileName
View.VectorType
4
General.OptionsFileName
View.Visible
1
-
View.Width
300
General.OptionsFileName
View.Color.Points
{0,0,0}
General.OptionsFileName
View.Color.Lines
{0,0,0}
General.OptionsFileName
View.Color.Triangles
{0,0,0}
General.OptionsFileName
View.Color.Quadrangles
{0,0,0}
General.OptionsFileName
View.Color.Tetrahedra
{0,0,0}
General.OptionsFileName
View.Color.Hexahedra
{0,0,0}
General.OptionsFileName
View.Color.Prisms
{0,0,0}
General.OptionsFileName
View.Color.Pyramids
{0,0,0}
General.OptionsFileName
View.Color.Tangents
{255,255,0}
General.OptionsFileName
View.Color.Normals
{255,0,0}
General.OptionsFileName
View.Color.Text2D
{0,0,0}
General.OptionsFileName
View.Color.Text3D
{0,0,0}
General.OptionsFileName
View.Color.Axes
{0,0,0}
General.OptionsFileName
View.ColorTable
General.OptionsFileName
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The nine following examples introduce new features gradually, starting with `t1.geo'. The files corresponding to these examples are available in the `tutorial' directory of the Gmsh distribution.
This tutorial does not explain the mesh and post-processing file formats: see 9. File formats, for this.
To learn how to run Gmsh on your computer, see 8. Running Gmsh. In addition, screencasts that show how to use the graphical user interface are available on Gmsh's webpage.
7.1 `t1.geo' 7.2 `t2.geo' 7.3 `t3.geo' 7.4 `t4.geo' 7.5 `t5.geo' 7.6 `t6.geo' 7.7 `t7.geo' 7.8 `t8.geo' 7.9 `t9.geo'
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/********************************************************************* * * Gmsh tutorial 1 * * Variables, elementary entities (points, lines, surfaces), physical * entities (points, lines, surfaces) * *********************************************************************/ // The simplest construction in Gmsh's scripting language is the // `affectation'. The following command defines a new variable `lc': lc = 0.009; // This variable can then be used in the definition of Gmsh's simplest // `elementary entity', a `Point'. A Point is defined by a list of // four numbers: three coordinates (X, Y and Z), and a characteristic // length (lc) that sets the target element size at the point: Point(1) = {0, 0, 0, lc}; // The distribution of the mesh element sizes is then obtained by // interpolation of these characteristic lengths throughout the // geometry. Another method to specify characteristic lengths is to // use a background mesh (see `t7.geo' and `bgmesh.pos'). // We can then define some additional points as well as our first // curve. Curves are Gmsh's second type of elementery entities, and, // amongst curves, straight lines are the simplest. A straight line is // defined by a list of point numbers. In the commands below, for // example, the line 1 starts at point 1 and ends at point 2: Point(2) = {.1, 0, 0, lc} ; Point(3) = {.1, .3, 0, lc} ; Point(4) = {0, .3, 0, lc} ; Line(1) = {1,2} ; Line(2) = {3,2} ; Line(3) = {3,4} ; Line(4) = {4,1} ; // The third elementary entity is the surface. In order to define a // simple rectangular surface from the four lines defined above, a // line loop has first to be defined. A line loop is a list of // connected lines, a sign being associated with each line (depending // on the orientation of the line): Line Loop(5) = {4,1,-2,3} ; // We can then define the surface as a list of line loops (only one // here, since there are no holes--see `t4.geo'): Plane Surface(6) = {5} ; // At this level, Gmsh knows everything to display the rectangular // surface 6 and to mesh it. An optional step is needed if we want to // associate specific region numbers to the various elements in the // mesh (e.g. to the line segments discretizing lines 1 to 4 or to the // triangles discretizing surface 6). This is achieved by the // definition of `physical entities'. Physical entities will group // elements belonging to several elementary entities by giving them a // common number (a region number), and specifying their orientation. // We can for example group the points 1 and 2 into the physical // entity 1: Physical Point(1) = {1,2} ; // Consequently, two punctual elements will be saved in the output // mesh file, both with the region number 1. The mechanism is // identical for line or surface elements: MyLine = 99; Physical Line(MyLine) = {1,2,4} ; Physical Surface("My fancy surface label") = {6} ; // All the line elements created during the meshing of lines 1, 2 and // 4 will be saved in the output mesh file with the region number 99; // and all the triangular elements resulting from the discretization // of surface 6 will be given an automatic region number (100, // associated with the label "My fancy surface label"). // Note that if no physical entities are defined, then all the // elements in the mesh will be saved "as is", with their default // orientation.
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/********************************************************************* * * Gmsh tutorial 2 * * Includes, geometrical transformations, extruded geometries, * elementary entities (volumes), physical entities (volumes) * *********************************************************************/ // We first include the previous tutorial file, in order to use it as // a basis for this one: Include "t1.geo"; // We can then add new points and lines in the same way as we did in // `t1.geo': Point(5) = {0, .4, 0, lc}; Line(5) = {4, 5}; // But Gmsh also provides tools to tranform (translate, rotate, etc.) // elementary entities or copies of elementary entities. For example, // the point 3 can be moved by 0.05 units to the left with: Translate {-0.05, 0, 0} { Point{3}; } // The resulting point can also be duplicated and translated by 0.1 // along the y axis: tmp[] = Translate {0, 0.1, 0} { Duplicata{ Point{3}; } } ; // In this case, we assigned the result of the Translate command to a // list, so that we can retrieve the number of the newly created point // and use it to create new lines and a new surface: Line(7) = {3,tmp[0]}; Line(8) = {tmp[0],5}; Line Loop(10) = {5,-8,-7,3}; Plane Surface(11) = {10}; // Of course, these transformation commands not only apply to points, // but also to lines and surfaces. We can for example translate a copy // of surface 6 by 0.12 units along the z axis and define some // additional lines and surfaces with: h = 0.12; Translate {0, 0, h} { Duplicata{ Surface{6}; } } Line(106) = {1,8}; Line(107) = {2,12}; Line(108) = {3,16}; Line(109) = {4,7}; Line Loop(110) = {1,107,-103,-106}; Plane Surface(111) = {110}; Line Loop(112) = {2,107,104,-108}; Plane Surface(113) = {112}; Line Loop(114) = {3,109,-105,-108}; Plane Surface(115) = {114}; Line Loop(116) = {4,106,-102,-109}; Plane Surface(117) = {116}; // Volumes are the fourth type of elementary entities in Gmsh. In the // same way one defines line loops to build surfaces, one has to // define surface loops (i.e. `shells') to build volumes. The // following volume does not have holes and thus consists of a single // surface loop: Surface Loop(118) = {117,-6,111,-113,101,115}; Volume(119) = {118}; // Another way to define a volume is by extruding a surface. The // following command extrudes the surface 11 along the z axis and // automatically creates a new volume: Extrude {0, 0, h} { Surface{11}; } // All these geometrical transformations automatically generate new // elementary entities. The following command permits to manually // assign a characteristic length to some of the new points: Characteristic Length {tmp[0], 2, 12, 3, 16, 6, 22} = lc * 4; // Note that, if the transformation tools are handy to create complex // geometries, it is also sometimes useful to generate the `flat' // geometry, with an explicit list of all elementary entities. This // can be achieved by selecting the `File->Save as->Gmsh unrolled // geometry' menu or by typing // // > gmsh t2.geo -0 // // on the command line. // To save all the tetrahedra discretizing the volumes 119 and 120 // with a common region number, we finally define a physical // volume: Physical Volume (1) = {119,120};
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/********************************************************************* * * Gmsh tutorial 3 * * Extruded meshes, options * *********************************************************************/ // Again, we start by including the first tutorial: Include "t1.geo"; // As in `t2.geo', we plan to perform an extrusion along the z axis. // But here, instead of only extruding the geometry, we also want to // extrude the 2D mesh. This is done with the same `Extrude' command, // but by specifying element 'Layers' (2 layers in this case, the // first one with 8 subdivisions and the second one with 2 // subdivisions, both with a height of h/2): h = 0.1; Extrude {0,0,h} { Surface{6}; Layers{ {8,2}, {0.5,1} }; } // The extrusion can also be performed with a rotation instead of a // translation, and the resulting mesh can be recombined into prisms // (we use only one layer here, with 7 subdivisions). All rotations // are specified by an axis direction ({0,1,0}), an axis point // ({-0.1,0,0.1}) and a rotation angle (-Pi/2): Extrude { {0,1,0} , {-0.1,0,0.1} , -Pi/2 } { Surface{122}; Layers{7}; Recombine; } // Note that a translation ({-2*h,0,0}) and a rotation ({1,0,0}, // {0,0.15,0.25}, Pi/2) can also be combined: out[] = Extrude { {-2*h,0,0}, {1,0,0} , {0,0.15,0.25} , Pi/2 } { Surface{news-1}; Layers{10}; Recombine; }; // In this last extrusion command we retrieved the volume number // programatically by saving the output of the command into a // list. This list will contain the "top" of the extruded surface (in // out[0]) as well as the newly created volume (in out[1]). // We can then define a new physical volume to save all the tetrahedra // with a common region number (101): Physical Volume(101) = {1, 2, out[1]}; // Let us now change some options... Since all interactive options are // accessible in Gmsh's scripting language, we can for example define // a global characteristic length factor or redefine some colors // directly in the input file: Mesh.CharacteristicLengthFactor = 4; General.Color.Text = White; Geometry.Color.Points = Orange; Mesh.Color.Points = {255,0,0}; // Note that all colors can be defined literally or numerically, i.e. // `Mesh.Color.Points = Red' is equivalent to `Mesh.Color.Points = // {255,0,0}'; and also note that, as with user-defined variables, the // options can be used either as right or left hand sides, so that the // following command will set the surface color to the same color as // the points: Geometry.Color.Surfaces = Geometry.Color.Points; // You can click on the `?' button in the status bar of the graphic // window to see the current values of all options. To save all the // options in a file, you can use the `File->Save as->Gmsh options' // menu. To save the current options as the default options for all // future Gmsh sessions, you should use the `Tools->Options->Save as // defaults' button.
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/********************************************************************* * * Gmsh tutorial 4 * * Built-in functions, holes, strings, mesh color * *********************************************************************/ // As usual, we start by defining some variables, some points and some // lines: cm = 1e-02; e1 = 4.5*cm; e2 = 6*cm / 2; e3 = 5*cm / 2; h1 = 5*cm; h2 = 10*cm; h3 = 5*cm; h4 = 2*cm; h5 = 4.5*cm; R1 = 1*cm; R2 = 1.5*cm; r = 1*cm; ccos = ( -h5*R1 + e2 * Hypot(h5,Hypot(e2,R1)) ) / (h5^2 + e2^2); ssin = Sqrt(1-ccos^2); Lc1 = 0.01; Lc2 = 0.003; Point(1) = { -e1-e2, 0.0 , 0.0 , Lc1}; Point(2) = { -e1-e2, h1 , 0.0 , Lc1}; Point(3) = { -e3-r , h1 , 0.0 , Lc2}; Point(4) = { -e3-r , h1+r , 0.0 , Lc2}; Point(5) = { -e3 , h1+r , 0.0 , Lc2}; Point(6) = { -e3 , h1+h2, 0.0 , Lc1}; Point(7) = { e3 , h1+h2, 0.0 , Lc1}; Point(8) = { e3 , h1+r , 0.0 , Lc2}; Point(9) = { e3+r , h1+r , 0.0 , Lc2}; Point(10)= { e3+r , h1 , 0.0 , Lc2}; Point(11)= { e1+e2, h1 , 0.0 , Lc1}; Point(12)= { e1+e2, 0.0 , 0.0 , Lc1}; Point(13)= { e2 , 0.0 , 0.0 , Lc1}; Point(14)= { R1 / ssin , h5+R1*ccos, 0.0 , Lc2}; Point(15)= { 0.0 , h5 , 0.0 , Lc2}; Point(16)= { -R1 / ssin , h5+R1*ccos, 0.0 , Lc2}; Point(17)= { -e2 , 0.0 , 0.0 , Lc1}; Point(18)= { -R2 , h1+h3 , 0.0 , Lc2}; Point(19)= { -R2 , h1+h3+h4, 0.0 , Lc2}; Point(20)= { 0.0 , h1+h3+h4, 0.0 , Lc2}; Point(21)= { R2 , h1+h3+h4, 0.0 , Lc2}; Point(22)= { R2 , h1+h3 , 0.0 , Lc2}; Point(23)= { 0.0 , h1+h3 , 0.0 , Lc2}; Point(24)= { 0 , h1+h3+h4+R2, 0.0 , Lc2}; Point(25)= { 0 , h1+h3-R2, 0.0 , Lc2}; Line(1) = {1 ,17}; Line(2) = {17,16}; // Gmsh provides other curve primitives than stright lines: splines, // B-splines, circle arcs, ellipse arcs, etc. Here we define a new // circle arc, starting at point 14 and ending at point 16, with the // circle's center being the point 15: Circle(3) = {14,15,16}; // Note that, in Gmsh, circle arcs should always be smaller than // Pi. We can then define additional lines and circles, as well as a // new surface: Line(4) = {14,13}; Line(5) = {13,12}; Line(6) = {12,11}; Line(7) = {11,10}; Circle(8) = {8,9,10}; Line(9) = {8,7}; Line(10) = {7,6}; Line(11) = {6,5}; Circle(12) = {3,4,5}; Line(13) = {3,2}; Line(14) = {2,1}; Line(15) = {18,19}; Circle(16) = {21,20,24}; Circle(17) = {24,20,19}; Circle(18) = {18,23,25}; Circle(19) = {25,23,22}; Line(20) = {21,22}; Line Loop(21) = {17,-15,18,19,-20,16}; Plane Surface(22) = {21}; // But we still need to define the exterior surface. Since this // surface has a hole, its definition now requires two lines loops: Line Loop(23) = {11,-12,13,14,1,2,-3,4,5,6,7,-8,9,10}; Plane Surface(24) = {23,21}; // Finally, we can add some comments by embedding a post-processing // view containing some strings, and change the color of some mesh // entities: View "comments" { // 10 pixels from the left and 15 pixels from the top of the graphic // window: T2(10,15,0){StrCat("File created on ", Today)}; // 10 pixels from the left and 10 pixels from the bottom of the // graphic window: T2(10,-10,0){"Copyright (C) My Company"}; // in the model, at (X,Y,Z) = (0.0,0.11,0.0): T3(0,0.11,0,0){"Hole"}; }; Color Grey50{ Surface{ 22 }; } Color Purple{ Surface{ 24 }; } Color Red{ Line{ 1:14 }; } Color Yellow{ Line{ 15:20 }; }
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/********************************************************************* * * Gmsh tutorial 5 * * Characteristic lengths, arrays of variables, functions, loops * *********************************************************************/ // Again, we start be defining some characteristic lengths: lcar1 = .1; lcar2 = .0005; lcar3 = .055; // If we wanted to change these lengths globally (without changing the // above definitions), we could give a global scaling factor for all // characteristic lengths on the command line with the `-clscale' // option (or with `Mesh.CharacteristicLengthFactor' in an option // file). For example, with: // // > gmsh t5.geo -clscale 1 // // this input file produces a mesh of approximately 3,000 nodes and // 15,000 tetrahedra. With // // > gmsh t5.geo -clscale 0.2 // // the mesh counts approximately 600,000 nodes and 3.6 million // tetrahedra. // We proceed by defining some elementary entities describing a // truncated cube: Point(1) = {0.5,0.5,0.5,lcar2}; Point(2) = {0.5,0.5,0,lcar1}; Point(3) = {0,0.5,0.5,lcar1}; Point(4) = {0,0,0.5,lcar1}; Point(5) = {0.5,0,0.5,lcar1}; Point(6) = {0.5,0,0,lcar1}; Point(7) = {0,0.5,0,lcar1}; Point(8) = {0,1,0,lcar1}; Point(9) = {1,1,0,lcar1}; Point(10) = {0,0,1,lcar1}; Point(11) = {0,1,1,lcar1}; Point(12) = {1,1,1,lcar1}; Point(13) = {1,0,1,lcar1}; Point(14) = {1,0,0,lcar1}; Line(1) = {8,9}; Line(2) = {9,12}; Line(3) = {12,11}; Line(4) = {11,8}; Line(5) = {9,14}; Line(6) = {14,13}; Line(7) = {13,12}; Line(8) = {11,10}; Line(9) = {10,13}; Line(10) = {10,4}; Line(11) = {4,5}; Line(12) = {5,6}; Line(13) = {6,2}; Line(14) = {2,1}; Line(15) = {1,3}; Line(16) = {3,7}; Line(17) = {7,2}; Line(18) = {3,4}; Line(19) = {5,1}; Line(20) = {7,8}; Line(21) = {6,14}; Line Loop(22) = {-11,-19,-15,-18}; Plane Surface(23) = {22}; Line Loop(24) = {16,17,14,15}; Plane Surface(25) = {24}; Line Loop(26) = {-17,20,1,5,-21,13}; Plane Surface(27) = {26}; Line Loop(28) = {-4,-1,-2,-3}; Plane Surface(29) = {28}; Line Loop(30) = {-7,2,-5,-6}; Plane Surface(31) = {30}; Line Loop(32) = {6,-9,10,11,12,21}; Plane Surface(33) = {32}; Line Loop(34) = {7,3,8,9}; Plane Surface(35) = {34}; Line Loop(36) = {-10,18,-16,-20,4,-8}; Plane Surface(37) = {36}; Line Loop(38) = {-14,-13,-12,19}; Plane Surface(39) = {38}; // Instead of using included files, we now use a user-defined function // in order to carve some holes in the cube: Function CheeseHole // In the following commands we use the reserved variable name // `newp', which automatically selects a new point number. This // number is chosen as the highest current point number, plus // one. (Note that, analogously to `newp', the variables `newc', // `news', `newv' and `newreg' select the highest number amongst // currently defined curves, surfaces, volumes and `any entities // other than points', respectively.) p1 = newp; Point(p1) = {x, y, z, lcar3} ; p2 = newp; Point(p2) = {x+r,y, z, lcar3} ; p3 = newp; Point(p3) = {x, y+r,z, lcar3} ; p4 = newp; Point(p4) = {x, y, z+r,lcar3} ; p5 = newp; Point(p5) = {x-r,y, z, lcar3} ; p6 = newp; Point(p6) = {x, y-r,z, lcar3} ; p7 = newp; Point(p7) = {x, y, z-r,lcar3} ; c1 = newreg; Circle(c1) = {p2,p1,p7}; c2 = newreg; Circle(c2) = {p7,p1,p5}; c3 = newreg; Circle(c3) = {p5,p1,p4}; c4 = newreg; Circle(c4) = {p4,p1,p2}; c5 = newreg; Circle(c5) = {p2,p1,p3}; c6 = newreg; Circle(c6) = {p3,p1,p5}; c7 = newreg; Circle(c7) = {p5,p1,p6}; c8 = newreg; Circle(c8) = {p6,p1,p2}; c9 = newreg; Circle(c9) = {p7,p1,p3}; c10 = newreg; Circle(c10) = {p3,p1,p4}; c11 = newreg; Circle(c11) = {p4,p1,p6}; c12 = newreg; Circle(c12) = {p6,p1,p7}; // We need non-plane surfaces to define the spherical holes. Here we // use ruled surfaces, which can have 3 or 4 sides: l1 = newreg; Line Loop(l1) = {c5,c10,c4}; Ruled Surface(newreg) = {l1}; l2 = newreg; Line Loop(l2) = {c9,-c5,c1}; Ruled Surface(newreg) = {l2}; l3 = newreg; Line Loop(l3) = {c12,-c8,-c1}; Ruled Surface(newreg) = {l3}; l4 = newreg; Line Loop(l4) = {c8,-c4,c11}; Ruled Surface(newreg) = {l4}; l5 = newreg; Line Loop(l5) = {-c10,c6,c3}; Ruled Surface(newreg) = {l5}; l6 = newreg; Line Loop(l6) = {-c11,-c3,c7}; Ruled Surface(newreg) = {l6}; l7 = newreg; Line Loop(l7) = {-c2,-c7,-c12};Ruled Surface(newreg) = {l7}; l8 = newreg; Line Loop(l8) = {-c6,-c9,c2}; Ruled Surface(newreg) = {l8}; // We then store the surface loops identification numbers in list // for later reference (we will need these to define the final // volume): theloops[t] = newreg ; Surface Loop(theloops[t]) = {l8+1,l5+1,l1+1,l2+1,l3+1,l7+1,l6+1,l4+1}; thehole = newreg ; Volume(thehole) = theloops[t] ; Return // We can use a `For' loop to generate five holes in the cube: x = 0 ; y = 0.75 ; z = 0 ; r = 0.09 ; For t In {1:5} x += 0.166 ; z += 0.166 ; Call CheeseHole ; // We define a physical volume for each hole: Physical Volume (t) = thehole ; // We also print some variables on the terminal (note that, since // all variables are treated internally as floating point numbers, // the format string should only contain valid floating point format // specifiers): Printf("Hole %g (center = {%g,%g,%g}, radius = %g) has number %g!", t, x, y, z, r, thehole) ; EndFor // We can then define the surface loop for the exterior surface of the // cube: theloops[0] = newreg ; Surface Loop(theloops[0]) = {35,31,29,37,33,23,39,25,27} ; // The volume of the cube, without the 5 holes, is now defined by 6 // surface loops (the exterior surface and the five interior loops). // To reference an array of variables, its identifier is followed by // '[]': Volume(186) = {theloops[]} ; // We finally define a physical volume for the elements discretizing // the cube, without the holes (whose elements were already tagged // with numbers 1 to 5 in the `For' loop): Physical Volume (10) = 186 ;
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/********************************************************************* * * Gmsh tutorial 6 * * Transfinite meshes * *********************************************************************/ // Let's use the geometry from the first tutorial as a basis for this // one Include "t1.geo"; // Put 20 equidistant points on curve 4 Transfinite Line{4} = 20 ; // Put 20 points with a refinement toward the extremities on curve 2 Transfinite Line{2} = 20 Using Bump 0.05; // Put 30 points following a geometric progression on curve 1 // (reversed) and on curve 3 Transfinite Line{-1,3} = 30 Using Progression 1.2; // Define the Surface as transfinite, by specifying the four corners // of the transfinite interpolation Transfinite Surface{6} = {1,2,3,4}; // (Note that the list on the right hand side refers to points, not // curves. The way triangles are generated can be controlled by // appending "Left", "Right" or "Alternate" after the list.) // Recombine the triangles into quads Recombine Surface{6}; // Apply an elliptic smoother to the grid Mesh.Smoothing = 100;
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/********************************************************************* * * Gmsh tutorial 7 * * Background mesh * *********************************************************************/ // Characteristic lengths can be specified very accuractely by // providing a background mesh, i.e., a post-processing view that // contains the target mesh sizes. // Merge the first tutorial Merge "t1.geo"; // Merge a post-processing view containing the target mesh sizes Merge "bgmesh.pos"; // Apply the view as the current background mesh Background Mesh View[0];
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/********************************************************************* * * Gmsh tutorial 8 * * Post-processing, scripting, animations, options * *********************************************************************/ // We first include `t1.geo' as well as some post-processing views: Include "t1.geo" ; Include "view1.pos" ; Include "view1.pos" ; Include "view4.pos" ; // We then set some general options: General.Trackball = 0 ; General.RotationX = 0 ; General.RotationY = 0 ; General.RotationZ = 0 ; General.Color.Background = White ; General.Color.Foreground = Black ; General.Color.Text = Black ; General.Orthographic = 0 ; General.Axes = 0 ; General.SmallAxes = 0 ; // We also set some options for each post-processing view: v0 = PostProcessing.NbViews-4; v1 = v0+1; v2 = v0+2; v3 = v0+3; View[v0].IntervalsType = 2 ; View[v0].OffsetZ = 0.05 ; View[v0].RaiseZ = 0 ; View[v0].Light = 1 ; View[v0].ShowScale = 0; View[v0].SmoothNormals = 1; View[v1].IntervalsType = 1 ; View[v1].ColorTable = { Green, Blue } ; View[v1].NbIso = 10 ; View[v1].ShowScale = 0; View[v2].Name = "Test..." ; View[v2].Axes = 1; View[v2].Color.Axes = Black; View[v2].IntervalsType = 2 ; View[v2].Type = 2; View[v2].IntervalsType = 2 ; View[v2].AutoPosition = 0; View[v2].PositionX = 85; View[v2].PositionY = 50; View[v2].Width = 200; View[v2].Height = 130; View[v3].Visible = 0; // We then loop from 1 to 255 with a step of 1. (To use a different // step, just add a third argument in the list. For example, `For num // In {0.5:1.5:0.1}' would increment num from 0.5 to 1.5 with a step // of 0.1.) t = 0 ; //For num In {1:1} For num In {1:255} View[v0].TimeStep = t ; View[v1].TimeStep = t ; View[v2].TimeStep = t ; View[v3].TimeStep = t ; t = (View[v0].TimeStep < View[v0].NbTimeStep-1) ? t+1 : 0 ; View[v0].RaiseZ += 0.01/View[v0].Max * t ; If (num == 3) // We want to create 320x240 frames when num == 3: General.GraphicsWidth = 320 ; General.GraphicsHeight = 240 ; EndIf // It is possible to nest loops: For num2 In {1:50} General.RotationX += 10 ; General.RotationY = General.RotationX / 3 ; General.RotationZ += 0.1 ; Sleep 0.01; // sleep for 0.01 second Draw; // draw the scene If (num == 3) // The `Print' command saves the graphical window; the `Sprintf' // function permits to create the file names on the fly: Print Sprintf("t8-%02g.gif", num2); Print Sprintf("t8-%02g.jpg", num2); EndIf EndFor If(num == 3) // Here we could make a system call to generate a movie. For example, // with whirlgif: // // System "whirlgif -minimize -loop -o t8.gif t8-*.gif"; // with mpeg_encode: // // System "mpeg_encode t8.par"; // with mencoder: // // System "mencoder 'mf://*.jpg' -mf fps=5 -o t8.mpg -ovc lavc // -lavcopts vcodec=mpeg1video:vhq"; // System "mencoder 'mf://*.jpg' -mf fps=5 -o t8.mpg -ovc lavc // -lavcopts vcodec=mpeg4:vhq"; // with ffmpeg: // // System "ffmpeg -hq -r 5 -b 800 -vcodec mpeg1video // -i t8-%02d.jpg t8.mpg" // System "ffmpeg -hq -r 5 -b 800 -i t8-%02d.jpg t8.asf" EndIf EndFor
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/********************************************************************* * * Gmsh tutorial 9 * * Post-processing plugins (levelsets, sections, annotations) * *********************************************************************/ // Plugins can be added to Gmsh in order to extend its // capabilities. For example, post-processing plugins can modify a // view, or create a new view based on previously loaded // views. Several default plugins are statically linked with Gmsh, // e.g. CutMap, CutPlane, CutSphere, Skin, Transform or Smooth. // Plugins can be controlled in the same way as other options: either // from the graphical interface (right click on the view button, then // `Plugins'), or from the command file. // Let us for example include a three-dimensional scalar view: Include "view3.pos" ; // We then set some options for the `CutMap' plugin (which extracts an // isovalue surface from a 3D scalar view), and run it: Plugin(CutMap).A = 0.67 ; // iso-value level Plugin(CutMap).iView = 0 ; // source view is View[0] Plugin(CutMap).Run ; // We also set some options for the `CutPlane' plugin (which computes // a section of a 3D view), and then run it: Plugin(CutPlane).A = 0 ; Plugin(CutPlane).B = 0.2 ; Plugin(CutPlane).C = 1 ; Plugin(CutPlane).D = 0 ; Plugin(CutPlane).Run ; // Add a title Plugin(Annotate).Text = "A nice title" ; // By convention, a value greater than 99999 represents the center (we // could also use `General.GraphicsWidth/2', but that would only center // the string for the current window size): Plugin(Annotate).X = 1.e5; Plugin(Annotate).Y = 50 ; Plugin(Annotate).Font = "Times-BoldItalic" ; Plugin(Annotate).FontSize = 28 ; Plugin(Annotate).Align = "Center" ; Plugin(Annotate).Run ; Plugin(Annotate).Text = "(and a small subtitle)" ; Plugin(Annotate).Y = 70 ; Plugin(Annotate).Font = "Times-Roman" ; Plugin(Annotate).FontSize = 12 ; Plugin(Annotate).Run ; // We finish by setting some options: View[0].Light = 1; View[0].IntervalsType = 1; View[0].NbIso = 6; View[0].SmoothNormals = 1; View[1].IntervalsType = 2; View[2].IntervalsType = 2;
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8.1 Interactive mode 8.2 Non-interactive mode 8.3 Command-line options 8.4 Mouse actions 8.5 Keyboard shortcuts
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Gmsh's first operating mode is the `interactive graphical mode'. To launch Gmsh in interactive mode, just click or double-click on the Gmsh icon (Windows and Mac), or type
> gmsh |
at your shell prompt in a terminal (Unix). This will open two windows: the graphic window (with a status bar at the bottom) and the menu window (with a menu bar and some context-dependent buttons).
To open the first tutorial file (see section 7. Tutorial), select the `File->Open' menu, and choose `t1.geo' in the input field. When using a terminal, you can also specify the file name directly on the command line, i.e.:
> gmsh t1.geo |
To perform the mesh generation, go to the mesh module (by selecting `Mesh' in the module menu) and choose the required dimension in the context-dependent buttons (`1D' will mesh all the lines; `2D' will mesh all the surfaces--as well as all the lines if `1D' was not called before; `3D' will mesh all the volumes--and all the surfaces if `2D' was not called before). To save the resulting mesh in the current mesh format, choose `Save' in the context-dependent buttons, or select the appropriate format with the `File->Save As' menu. The default mesh file name is based on the name of the first input file on the command line (or `untitled' if there wasn't any input file given), with an appended extension depending on the mesh format(7).
To create a new geometry or to modify an existing geometry, select 'Geometry' in the module menu, and follow the context-dependent buttons. For example, to create a spline, select `Elementary', `Add', `New' and `Spline'. You will then be asked to select a list of points, and to type e to finish the selection (or q to abort it). Once the interactive command is completed, a text string is automatically added at the end of the current project file. You can edit this project file by hand at any time by pressing the `Edit' button in the `Geometry' menu and then reloading the project by pressing `Reload'. For example, it is often faster to define variables and points directly in the project file, and then use the graphical user interface to define the lines, the surfaces and the volumes interactively.
Several files can be loaded simultaneously in Gmsh. The first one defines the project, while the others are appended (`merged') to this project. You can merge such files with the `File->Merge' menu, or by directly specifying the names of the files on the command line. For example, to merge the post-processing views contained in the files `view1.pos' and `view2.pos' together with the geometry of the first tutorial `t1.geo', you can type the following command:
> gmsh t1.geo view1.pos view2.pos |
In the Post-Processing module (select `Post-Processing' in the module menu), two view buttons will appear, respectively labeled `a scalar map' and `a vector map'. A mouse click on the name will toggle the visibility of the selected view, while a click on the arrow button on the right will provide access to the view's options. If you want the modifications made to one view to affect also all the other views, select the `Apply next changes to all views' or `Force same options for all views' option in the `Tools->Options->Post-processing' menu.
Note that all the options specified interactively can also be directly specified in the ASCII input files. All available options, with their current values, can be saved into a file by selecting `File->Save As->Gmsh options', or simply viewed by pressing the `?' button in the status bar. To save the current options as your default preferences for all future Gmsh sessions, use the `Tools->Options->Save as defaults' button.
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Gmsh's second operating mode is the non-interactive (or `batch') mode. In this mode, there is no graphical user interface, and all operations are performed without any user interaction(8). For example, to mesh the first tutorial in non-interactive mode, just type:
> gmsh t1.geo -2 |
To mesh the same example, but with the background mesh available in the file `bgmesh.pos', type:
> gmsh t1.geo -2 -bgm bgmesh.pos |
For the list of all command-line options, see 8.3 Command-line options.
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Geometry options:
-0
-tol float
Mesh options:
-1, -2, -3
-saveall
-o file
-format string
-bin
-algo string
-smooth int
-optimize[_netgen]
-order int
-clscale float
-clmin float
-clmax float
-clcurv
-rand float
-bgm file
-constrain
Post-processing options:
-noview
-link int
-combine
Display options:
-nodb
-fontsize int
-theme string
-display string
Other options:
-
-a, -g, -m, -s, -p
-pid
-listen
-v int
-nopopup
-string "string"
-option file
-convert files
-version
-info
-help
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In the following, for a 2 button mouse, Middle button = Shift+Left button. For a 1 button mouse, Middle button = Shift+Left button and Right button = Alt+Left button.
Move the mouse:
Left button:
Ctrl+Left button: Start a lasso zoom or a lasso selection/unselection
Middle button:
Ctrl+Middle button: Orthogonalize display
Right button:
Ctrl+Right button: Reset to default viewpoint
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(On Mac Ctrl is replaced by Cmd (the `Apple key') in the shortcuts below.)
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This chapter describes Gmsh's native "MSH" file format, used to store meshes and associated post-processing datasets. The MSH format exists in two flavors: ASCII and binary. The format has a version number (currently: 2.0) that is independent of Gmsh's main version number.
9.1 MSH ASCII file format 9.2 MSH binary file format 9.3 Node ordering 9.4 Legacy formats
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The MSH ASCII file format contains one mandatory section giving
information about the file ($MeshFormat
), followed by several
optional sections defining the nodes ($Nodes
), elements
($Elements
), region names ($PhysicalName
) and
post-processing datasets ($NodeData
, $ElementData
,
$ElementNodeData
). Sections can be repeated in the same file, and
post-processing sections can be put into separate files (e.g. one file
per time step).
The format is defined as follows:
$MeshFormat version-number file-type data-size $EndMeshFormat $Nodes number-of-nodes node-number x-coord y-coord z-coord ... $EndNodes $Elements number-of-elements elm-number elm-type number-of-tags < tag > ... node-number-list ... $EndElements $PhysicalNames number-of-names phyical-number "physical-name" ... $EndPhysicalNames $NodeData number-of-string-tags < "string-tag" > ... number-of-real-tags < real-tag > ... number-of-integer-tags < integer-tag > ... node-number value ... ... $EndNodeData $ElementData number-of-string-tags < "string-tag" > ... number-of-real-tags < real-tag > ... number-of-integer-tags < integer-tag > ... elm-number value ... ... $EndElementData $ElementNodeData number-of-string-tags < "string-tag" > ... number-of-real-tags < real-tag > ... number-of-integer-tags < integer-tag > ... elm-number number-of-nodes-per-element value ... ... $ElementEndNodeData |
where
version-number
file-type
data-size
number-of-nodes
node-number
x-coord y-coord z-coord
number-of-elements
elm-number
elm-type
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
number-of-tags
node-number-list
number-of-string-tags
number-of-real-tags
number-of-integer-tags
number-of-nodes-per-elements
value
NodeData
(respectively ElementData
) views,
there are ncomp values per node (resp. per element), where
ncomp is the number of field components. For
ElementNodeData
views, there are ncomp times
number-of-nodes-per-elements values per element.
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The binary file format is similar to the ASCII format described above:
$MeshFormat version-number file-type data-size one-binary $EndMeshFormat $Nodes number-of-nodes nodes-binary $EndNodes $Elements number-of-elements element-header-binary elements-binary element-header-binary elements-binary ... $EndElements [ all other sections are identical to ASCII, except that node-number, elm-number, number-of-nodes-per-element and values are written in binary format ] |
where
version-number
file-type
data-size
one-binary
Here is a pseudo C code to write one-binary:
int one = 1; fwrite(&one, sizeof(int), 1, file); |
number-of-nodes
nodes-binary
Here is a pseudo C code to write nodes-binary:
for(i = 0; i < number_of_nodes; i++){ fwrite(&num_i, sizeof(int), 1, file); double xyz[3] = {node_i_x, node_i_y, node_i_z}; fwrite(&xyz, sizeof(double), 3, file); } |
number-of-elements
element-header-binary
Here is a pseudo C code to write element-header-binary:
int header[3] = {elm_type, num_elm_follow, num_tags}; fwrite(&header, sizeof(int), 3, file); |
elements-binary
Here is a pseudo C code to write elements-binary for triangles with the 3 standard tags (the physical and elementary regions, and the mesh partition):
for(i = 0; i < number_of_triangles; i++){ int data[7] = {num_i, physical, elementary, partition, node_i_1, node_i_2, node_i_3}; fwrite(data, sizeof(int), 7, file); } |
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For all mesh and post-processing file formats, the reference elements are defined as follows.
Line: Line3: 0----------1 --> u 0-----2----1 |
Triangle: Triangle6: v ^ | 2 2 |`\ |`\ | `\ | `\ | `\ 5 `4 | `\ | `\ | `\ | `\ 0----------1 --> u 0-----3----1 |
Quadrangle: Quadrangle8: Quadrangle9: v ^ | 3-----------2 3-----6-----2 3-----6-----2 | | | | | | | | | | | | | | | +---- | --> u 7 5 7 8 5 | | | | | | | | | | | | 0-----------1 0-----4-----1 0-----4-----1 |
Tetrahedron: Tetrahedron10: v . ,/ / 2 2 ,/|`\ ,/|`\ ,/ | `\ ,/ | `\ ,/ '. `\ ,6 '. `5 ,/ | `\ ,/ 8 `\ ,/ | `\ ,/ | `\ 0-----------'.--------1 --> u 0--------4--'.--------1 `\. | ,/ `\. | ,/ `\. | ,/ `\. | ,9 `\. '. ,/ `7. '. ,/ `\. |/ `\. |/ `3 `3 `\. ` w |
Hexahedron: Hexahedron20: Hexahedron27: v 3----------2 3----13----2 3----13----2 |\ ^ |\ |\ |\ |\ |\ | \ | | \ | 15 | 14 |15 24 | 14 | \ | | \ 9 \ 11 \ 9 \ 20 11 \ | 7------+---6 | 7----19+---6 | 7----19+---6 | | +-- |-- | -> u | | | | |22 | 26 | 23| 0---+---\--1 | 0---+-8----1 | 0---+-8----1 | \ | \ \ | \ 17 \ 18 \ 17 25 \ 18 \ | \ \ | 10 | 12| 10 | 21 12| \| w \| \| \| \| \| 4----------5 4----16----5 4----16----5 |
Prism: Prism15: Prism18: w ^ | 3 3 3 ,/|`\ ,/|`\ ,/|`\ ,/ | `\ 12 | 13 12 | 13 ,/ | `\ ,/ | `\ ,/ | `\ 4------+------5 4------14-----5 4------14-----5 | | | | 8 | | 8 | | ,/|`\ | | | | | ,/|`\ | | ,/ | `\ | | | | | 15 | 16 | |,/ | `\| | | | |,/ | `\| ,| | `\ 10 | 11 10-----17-----11 ,/ | 0 | `\ | 0 | | 0 | u | ,/ `\ | v | ,/ `\ | | ,/ `\ | | ,/ `\ | | ,6 `7 | | ,6 `7 | |,/ `\| |,/ `\| |,/ `\| 1-------------2 1------9------2 1------9------2 |
Pyramid: Pyramid13: Pyramid14: 4 4 4 ,/|\ ,/|\ ,/|\ ,/ .'|\ ,/ .'|\ ,/ .'|\ ,/ | | \ ,/ | | \ ,/ | | \ ,/ .' | `. ,/ .' | `. ,/ .' | `. ,/ | '. \ ,7 | 12 \ ,7 | 12 \ ,/ .' w | \ ,/ .' | \ ,/ .' | \ ,/ | ^ | \ ,/ 9 | 11 ,/ 9 | 11 0----------.'--|-3 `. 0--------6-.'----3 `. 0--------6-.'----3 `. `\ | | `\ \ `\ | `\ \ `\ | `\ \ `\ .' +----`\ - \ -> v `5 .' 10 \ `5 .' 13 10 \ `\ | `\ `\ \ `\ | `\ \ `\ | `\ \ `\.' `\ `\` `\.' `\` `\.' `\` 1----------------2 1--------8-------2 1--------8-------2 `\ u |
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This section describes Gmsh's older native file formats. Future versions of Gmsh will continue to support these formats, but we recommend that you do not use them in new aplications.
9.4.1 MSH file format version 1.0 9.4.2 POS ASCII file format 9.4.3 POS binary file format
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The MSH file format version 1.0 is Gmsh's old native mesh file format, now superseded by the format described in 9.1 MSH ASCII file format. It is defined as follows:
$NOD number-of-nodes node-number x-coord y-coord z-coord ... $ENDNOD $ELM number-of-elements elm-number elm-type reg-phys reg-elem number-of-nodes node-number-list ... $ENDELM |
where
number-of-nodes
node-number
x-coord y-coord z-coord
number-of-elements
elm-number
elm-type
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
reg-phys
reg-elem
number-of-nodes
node-number-list
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The POS ASCII file is Gmsh's old native pot-processing format, now superseded by the format described in 9.1 MSH ASCII file format. It is defined as follows:
$PostFormat 1.4 file-type data-size $EndPostFormat $View view-name nb-time-steps nb-scalar-points nb-vector-points nb-tensor-points nb-scalar-lines nb-vector-lines nb-tensor-lines nb-scalar-triangles nb-vector-triangles nb-tensor-triangles nb-scalar-quadrangles nb-vector-quadrangles nb-tensor-quadrangles nb-scalar-tetrahedra nb-vector-tetrahedra nb-tensor-tetrahedra nb-scalar-hexahedra nb-vector-hexahedra nb-tensor-hexahedra nb-scalar-prisms nb-vector-prisms nb-tensor-prisms nb-scalar-pyramids nb-vector-pyramids nb-tensor-pyramids nb-scalar-lines2 nb-vector-lines2 nb-tensor-lines2 nb-scalar-triangles2 nb-vector-triangles2 nb-tensor-triangles2 nb-scalar-quadrangles2 nb-vector-quadrangles2 nb-tensor-quadrangles2 nb-scalar-tetrahedra2 nb-vector-tetrahedra2 nb-tensor-tetrahedra2 nb-scalar-hexahedra2 nb-vector-hexahedra2 nb-tensor-hexahedra2 nb-scalar-prisms2 nb-vector-prisms2 nb-tensor-prisms2 nb-scalar-pyramids2 nb-vector-pyramids2 nb-tensor-pyramids2 nb-text2d nb-text2d-chars nb-text3d nb-text3d-chars time-step-values < scalar-point-value > ... < vector-point-value > ... < tensor-point-value > ... < scalar-line-value > ... < vector-line-value > ... < tensor-line-value > ... < scalar-triangle-value > ... < vector-triangle-value > ... < tensor-triangle-value > ... < scalar-quadrangle-value > ... < vector-quadrangle-value > ... < tensor-quadrangle-value > ... < scalar-tetrahedron-value > ... < vector-tetrahedron-value > ... < tensor-tetrahedron-value > ... < scalar-hexahedron-value > ... < vector-hexahedron-value > ... < tensor-hexahedron-value > ... < scalar-prism-value > ... < vector-prism-value > ... < tensor-prism-value > ... < scalar-pyramid-value > ... < vector-pyramid-value > ... < tensor-pyramid-value > ... < scalar-line2-value > ... < vector-line2-value > ... < tensor-line2-value > ... < scalar-triangle2-value > ... < vector-triangle2-value > ... < tensor-triangle2-value > ... < scalar-quadrangle2-value > ... < vector-quadrangle2-value > ... < tensor-quadrangle2-value > ... < scalar-tetrahedron2-value > ... < vector-tetrahedron2-value > ... < tensor-tetrahedron2-value > ... < scalar-hexahedron2-value > ... < vector-hexahedron2-value > ... < tensor-hexahedron2-value > ... < scalar-prism2-value > ... < vector-prism2-value > ... < tensor-prism2-value > ... < scalar-pyramid2-value > ... < vector-pyramid2-value > ... < tensor-pyramid2-value > ... < text2d > ... < text2d-chars > ... < text3d > ... < text3d-chars > ... $EndView |
where
file-type
data-size
view-name
nb-time-steps
nb-scalar-points
nb-vector-points
...
nb-text2d
nb-text3d
nb-text2d-chars
nb-text3d-chars
time-step-values
scalar-point-value
vector-point-value
...
For example, vector-triangle-value is defined as:
coord1-node1 coord1-node2 coord1-node3 coord2-node1 coord2-node2 coord2-node3 coord3-node1 coord3-node2 coord3-node3 comp1-node1-time1 comp2-node1-time1 comp3-node1-time1 comp1-node2-time1 comp2-node2-time1 comp3-node2-time1 comp1-node3-time1 comp2-node3-time1 comp3-node3-time1 comp1-node1-time2 comp2-node1-time2 comp3-node1-time2 comp1-node2-time2 comp2-node2-time2 comp3-node2-time2 comp1-node3-time2 comp2-node3-time2 comp3-node3-time2 ... |
The ordering of the nodes is given in 9.3 Node ordering.
text2d
coord1 coord2 style index |
text2d-chars
\0
' character.
text3d
coord1 coord2 coord3 style index |
text3d-chars
\0
' character.
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The POS binary file format is the same as the POS ASCII file format described in 9.4.2 POS ASCII file format, except that:
Here is a pseudo C code to write a post-processing file in binary format:
int one = 1; fprintf(file, "$PostFormat\n"); fprintf(file, "%g %d %d\n", 1.4, 1, sizeof(double)); fprintf(file, "$EndPostFormat\n"); fprintf(file, "$View\n"); fprintf(file, "%s %d " "%d %d %d %d %d %d %d %d %d " "%d %d %d %d %d %d %d %d %d " "%d %d %d %d %d %d %d %d %d " "%d %d %d %d %d %d %d %d %d " "%d %d %d %d %d %d %d %d %d " "%d %d %d %d\n", view-name, nb-time-steps, nb-scalar-points, nb-vector-points, nb-tensor-points, nb-scalar-lines, nb-vector-lines, nb-tensor-lines, nb-scalar-triangles, nb-vector-triangles, nb-tensor-triangles, nb-scalar-quadrangles, nb-vector-quadrangles, nb-tensor-quadrangles, nb-scalar-tetrahedra, nb-vector-tetrahedra, nb-tensor-tetrahedra, nb-scalar-hexahedra, nb-vector-hexahedra, nb-tensor-hexahedra, nb-scalar-prisms, nb-vector-prisms, nb-tensor-prisms, nb-scalar-pyramids, nb-vector-pyramids, nb-tensor-pyramids, nb-scalar-lines2, nb-vector-lines2, nb-tensor-lines2, nb-scalar-triangles2, nb-vector-triangles2, nb-tensor-triangles2, nb-scalar-quadrangles2, nb-vector-quadrangles2, nb-tensor-quadrangles2, nb-scalar-tetrahedra2, nb-vector-tetrahedra2, nb-tensor-tetrahedra2, nb-scalar-hexahedra2, nb-vector-hexahedra2, nb-tensor-hexahedra2, nb-scalar-prisms2, nb-vector-prisms2, nb-tensor-prisms2, nb-scalar-pyramids2, nb-vector-pyramids2, nb-tensor-pyramids2, nb-text2d, nb-text2d-chars, nb-text3d, nb-text3d-chars); fwrite(&one, sizeof(int), 1, file); fwrite(time-step-values, sizeof(double), nb-time-steps, file); fwrite(all-scalar-point-values, sizeof(double), ..., file); ... fprintf(file, "\n$EndView\n"); |
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Gmsh is written in C++, the scripting language is parsed using Lex and Yacc (actually, Flex and Bison), and the GUI relies on OpenGL for the 3D graphics and FLTK (http://www.fltk.org) for the widget set. Gmsh's build system is based on autoconf. Practical notes on how to compile Gmsh's source code are included in the distribution. See B. Frequently asked questions, for more information.
10.1 Main code structure 10.2 Coding style 10.3 Option handling
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Gmsh's code is structured in several libraries, roughly separated between the three main core modules (Geo, Mesh, Post) and associated utility libraries (Common, Numeric) on one hand, and graphics (Graphics) and interface (Fltk, Box) libraries on the other.
The geometry and mesh modules are based on an object-oriented model class (Geo/GModel.h), built upon abstract geometrical entity classes (Geo/GVertex.h, Geo/Gedge.h, Geo/GFace.h and Geo/GRegion.h).
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If you plan to contribute code to the Gmsh project, here are some easy rules to make the code easy to read/debug/maintain:
-Wall
to
FLAGS
in the `variables' file);
Msg()
function to print information, errors, ...;
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To add a new option in Gmsh:
Context_T
class
(`Common/Context.h') if it's a classical option, or in the
PViewOptions
class (`Post/PViewOptions.h') if it's a
post-processing view-dependent option;
opt_XXX
) and a
default value for this option;
opt_XXX
in `Common/Options.cpp' (and
add the prototype in `Common/Options.h');
opt_XXX
to the OK callback for the corresponding
option panel (in `Fltk/Callbacks.cpp').
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11.1 Bugs 11.2 Versions 11.3 Credits
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If you think you have found a bug in Gmsh, you can report it by electronic mail to the Gmsh mailing list at gmsh@geuz.org. Please send as precise a description of the problem as you can, including sample input files that produce the bug. Don't forget to mention both the version of Gmsh and the version of your operation system (see section 8.3 Command-line options to see how to get this information).
See B. Frequently asked questions, and the `TODO.txt' file in the distribution to see which problems we already know about.
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$Id: VERSIONS.txt,v 1.2 2008-07-14 19:02:22 geuzaine Exp $ 2.2.3 (Jul 14, 2008): enhanced clipping interface; API cleanup; fixed various bugs (Plugin(Integrate), high order meshes, surface info crash). 2.2.2 (Jun 20, 2008): added geometrical transformations on volumes; fixed bug in high order mesh generation. 2.2.1 (Jun 15, 2008): various small improvements (adaptive views, gui, code cleanup) and bug fixes (high order meshes, Netgen interface). 2.2.0 (Apr 19, 2008): new model-based post-processing backend; added MED I/O for mesh and post-processing; fixed BDF vertex ordering for 2nd order elements; replaced Mesh.ConstrainedBackgroundMesh with Mesh.CharacteristicLength{FromPoints,ExtendFromBoundary}; new Fields interface; control windows are now non-modal by default; new experimental 2D frontal algorithm; fixed various bugs. 2.1.1 (Mar 1, 2008): small bug fixes (second order meshes, combine views, divide and conquer crash, ...). 2.1.0 (Feb 23, 2008): new post-processing database; complete rewrite of post-processing drawing code; improved surface mesh algorithms; improved STEP/IGES/BREP support; new 3D mesh optimization algorithm; new default native file choosers; fixed 'could not find extruded vertex' in extrusions; many improvements and bug fixes all over the place. 2.0.8 (Jul 13, 2007): unused vertices are not saved in mesh files anymore; new plugin GUI; automatic GUI font size selection; renamed Plugin(DecomposeInSimplex) into Plugin(MakeSimplex); reintroduced enhanced Plugin(SphericalRaise); clarified meshing algo names; new option to save groups of nodes in UNV meshes; new background mesh infrastructure; many small improvements and small bug fixes. 2.0.7 (Apr 3, 2007): volumes can now be defined from external CAD surfaces; Delaunay/Tetgen algorithm is now used by default when available; re-added support for Plot3D structured mesh format; added ability to export external CAD models as GEO files (this only works for the limited set of geometrical primitives available in the GEO language, of course--so trying to convert e.g. a trimmed NURBS from a STEP file into a GEO file will fail); "lateral" entities are now added at the end of the list returned by extrusion commands; fixed various bugs. 2.0 (Feb 5, 2007): new geometry and mesh databases, with support for STEP and IGES import via OpenCascade; complete rewrite of geometry and mesh drawing code; complete rewrite of mesh I/O layer (with new native binary MSH format and support for import/export of I-deas UNV, Nastran BDF, STL, Medit MESH and VRML 1.0 files); added support for incomplete second order elements; new 2D and 3D meshing algorithms; improved integration of Netgen and TetGen algorithms; removed anisotropic meshing algorithm (as well as attractors); removed explicit region number specification in extrusions; option changes in the graphical interface are now applied instantaneously; added support for offscreen rendering using OSMesa; added support for SVG output; added string labels for Physical entities; lots of other improvements all over the place. 1.65 (May 15, 2006): new Plugin(ExtractEdges); fixed compilation errors with gcc4.1; replaced Plugin(DisplacementRaise) and Plugin(SphericalRaise) with the more flexible Plugin(Warp); better handling of discrete curves; new Status command in parser; added option to renumber nodes in .msh files (to avoid holes in the numbering sequence); fixed 2 special cases in quad->prism extrusion; fixed saving of 2nd order hexas with negative volume; small bug fixes and cleanups. 1.64 (Mar 18, 2006): Windows versions do no depend on Cygwin anymore; various bug fixes and cleanups. 1.63 (Feb 01, 2006): post-processing views can now be exported as meshes; improved background mesh handling (a lot faster, and more accurate); improved support for input images; new Plugin(ExtractElements); small bug fixes and enhancements. 1.62 (Jan 15, 2006): new option to draw color gradients in the background; enhanced perspective projection mode; new "lasso" selection mode (same as "lasso" zoom, but in selection mode); new "invert selection" button in the visibility browser; new snapping grid when adding points in the GUI; nicer normal smoothing; new extrude syntax (old syntax still available, but deprecated); various small bug fixes and enhancements. 1.61 (Nov 29, 2005): added support for second order (curved) elements in post-processor; new version (1.4) of post-processing file formats; new stippling options for 2D plots; removed limit on allowed number of files on command line; all "Combine" operations are now available in the parser; changed View.ArrowLocation into View.GlyphLocation; optimized memory usage when loading many (>1000) views; optimized loading and drawing of line meshes and 2D iso views; optimized handling of meshes with large number of physical entities; optimized vertex array creation for large post-processing views on Windows/Cygwin; removed Discrete Line and Discrete Surface commands (the same functionality can now be obtained by simply loading a mesh in .msh format); fixed coloring by mesh partition; added option to light wireframe meshes and views; new "mesh statistics" export format; new full-quad recombine option; new Plugin(ModulusPhase); hexas and prisms are now always saved with positive volume; improved interactive entity selection; new experimental Tetgen integration; new experimental STL remeshing algorithm; various small bug fixes and improvements. 1.60 (Mar 15, 2005): added support for discrete curves; new Window menu on Mac OS X; generalized all octree-based plugins (CutGrid, StreamLines, Probe, etc.) to handle all element types (and not only scalar and vector triangles+tetrahedra); generalized Plugin(Evaluate), Plugin(Extract) and Plugin(Annotate); enhanced clipping plane interface; new grid/axes/rulers for 3D post-processing views (renamed the AbscissaName, NbAbscissa and AbscissaFormat options to more general names in the process); better automatic positioning of 2D graphs; new manipulator dialog to specify rotations, translations and scalings "by hand"; various small enhancements and bug fixes. 1.59 (Feb 06, 2005): added support for discrete (triangulated) surfaces, either in STL format or with the new "Discrete Surface" command; added STL and Text output format for post-processing views and STL output format for surface meshes; all levelset-based plugins can now also compute isovolumes; generalized Plugin(Evaluate) to handle external view data (based on the same or on a different mesh); generalized Plugin(CutGrid); new plugins (Eigenvalues, Gradient, Curl, Divergence); changed default colormap to match Matlab's "Jet" colormap; new transformation matrix option for views (for non-destructive rotations, symmetries, etc.); improved solver interface to keep the GUI responsive during solver calls; new C++ and Python solver examples; simplified Tools->Visibility GUI; transfinite lines with "Progression" now allow negative line numbers to reverse the progression; added ability to retrieve Gmsh's version number in the parser (to help write backward compatible scripts); fixed white space in unv mesh output; fixed various small bugs. 1.58 (Jan 01, 2005): fixed UNIX socket interface on Windows (broken by the TCP solver patch in 1.57); bumped version number of default post-processing file formats to 1.3 (the only small modification is the handling of the end-of-string character for text2d and text3d objects in the ASCII format); new File->Rename menu; new colormaps+improved colormap handling; new color+min/max options in views; new GetValue() function to ask for values interactively in scripts; generalized For/EndFor loops in parser; new plugins (Annotate, Remove, Probe); new text attributes in views; renamed some shortcuts; fixed TeX output for large scenes; new option dialogs for various output formats; fixed many small memory leaks in parser; many small enhancements to polish the graphics and the user interface. 1.57 (Dec 23, 2004): generalized displacement maps to display arbitrary view types; the arrows representing a vector field can now also be colored by the values from other scalar, vector or tensor fields; new adaptive high order visualization mode; new options (Solver.SocketCommand, Solver.NameCommand, View.ArrowSizeProportional, View.Normals, View.Tangents and General.ClipFactor); fixed display of undesired solver plugin popups; enhanced interactive plugin behavior; new plugins (HarmonicToTime, Integrate, Eigenvectors); tetrahedral mesh file reading speedup (50% faster on large meshes); large memory footprint reduction (up to 50%) for the visualization of triangular/tetrahedral meshes; the solver interface now supports TCP/IP connections; new generalized raise mode (allows to use complex expressions to offset post-processing maps); upgraded Netgen kernel to version 4.4; new optional TIME list in parsed views to specify the values of the time steps; several bug fixes in the Elliptic mesh algorithm; various other small bug fixes and enhancements. 1.56 (Oct 17, 2004): new post-processing option to draw a scalar view raised by a displacement view without using Plugin(DisplacementRaise) (makes drawing arbitrary scalar fields on deformed meshes much easier); better post-processing menu (arbitrary number of views+scrollable+show view number); improved view->combine; new horizontal post-processing scales; new option to draw the mesh nodes per element; views can now also be saved in "parsed" format; fixed various path problems on Windows; small bug fixes. 1.55 (Aug 21, 2004): added background mesh support for Triangle; meshes can now be displayed using "smoothed" normals (like post-processing views); added GUI for clipping planes; new interactive clipping/cutting plane definition; reorganized the Options GUI; enhanced 3D iso computation; enhanced lighting; many small bug fixes. 1.54 (Jul 03, 2004): integrated Netgen (3D mesh quality optimization + alternative 3D algorithm); Extrude Surface now always automatically creates a new volume (in the same way Extrude Point or Extrude Line create new lines and surfaces, respectively); fixed UNV output; made the "Layers" region numbering consistent between lines, surfaces and volumes; fixed home directory problem on Win98; new Plugin(CutParametric); the default project file is now created in the home directory if no current directory is defined (e.g., when double-clicking on the icon on Windows/Mac); fixed the discrepancy between the orientation of geometrical surfaces and the associated surface meshes; added automatic orientation of surfaces in surface loops; generalized Plugin(Triangulate) to handle vector and tensor views; much nicer display of discrete iso-surfaces and custom ranges using smooth normals; small bug fixes and cleanups. 1.53 (Jun 04, 2004): completed support for second order elements in the mesh module (line, triangles, quadrangles, tetrahedra, hexahedra, prisms and pyramids); various background mesh fixes and enhancements; major performance improvements in mesh and post-processing drawing routines (OpenGL vertex arrays for tri/quads); new Plugin(Evaluate) to evaluate arbitrary expressions on post-processing views; generalized Plugin(Extract) to handle any combination of components; generalized "Coherence" to handle transfinite surface/volume attributes; plugin options can now be set in the option file (like all other options); added "undo" capability during geometry creation; rewrote the contour guessing routines so that entities can be selected in an arbitrary order; Mac users can now double click on geo/msh/pos files in the Finder to launch Gmsh; removed support for FLTK 1.0; rewrote most of the code related to quadrangles; fixed 2d elliptic algorithm; removed all OpenGL display list code and options; fixed light positioning; new BoundingBox command to set the bounding box explicitly; added support for inexpensive "fake" transparency mode; many code cleanups. 1.52 (May 06, 2004): new raster ("bitmap") PostScript/EPS/PDF output formats; new Plugin(Extract) to extract a given component from a post-processing view; new Plugin(CutGrid) and Plugin(StreamLines); improved mesh projection on non-planar surfaces; added support for second order tetrahedral elements; added interactive control of element order; refined mesh entity drawing selection (and renamed most of the corresponding options); enhanced log scale in post-processing; better font selection; simplified View.Raise{X,Y,Z} by removing the scaling; various bug fixes (default postscript printing mode, drawing of 3D arrows/cylinders on Linux, default home directory on Windows, default initial file browser directory, extrusion of points with non-normalized axes of rotation, computation of the scene bounding box in scripts, + the usual documentation updates). 1.51 (Feb 29, 2004): initial support for visualizing mesh partitions; integrated version 2.0 of the MSH mesh file format; new option to compute post-processing ranges (min/max) per time step; Multiple views can now be combined into multi time step ones (e.g. for programs that generate data one time step at a time); new syntax: #var[] returns the size of the list var[]; enhanced "gmsh -convert"; temporary and error files are now created in the home directory to avoid file permission issues; new 3D arrows; better lighting support; STL facets can now be converted into individual geometrical surfaces; many other small improvements and bug fixes (multi timestep tensors, color by physical entity, parser cleanup, etc.). 1.50 (Dec 06, 2003): small changes to the visibility browser + made visibility scriptable (new Show/Hide commands); fixed (rare) crash when deleting views; split File->Open into File->Open and File->New to behave like most other programs; Mac versions now use the system menu bar by default (if possible); fixed bug leading to degenerate and/or duplicate tetrahedra in extruded meshes; fixed crash when reloading sms meshes. 1.49 (Nov 30, 2003): made Merge, Save and Print behave like Include (i.e., open files in the same directory as the main project file if the path is relative); new Plugin(DecomposeInSimplex); new option View.AlphaChannel to set the transparency factor globally for a post-processing view; new "Combine Views" command; various bug fixes and cleanups. 1.48 (Nov 23, 2003): new DisplacementRaise plugin to plot arbitrary fields on deformed meshes; generalized CutMap, CutPlane, CutSphere and Skin plugins to handle all kinds of elements and fields; new "Save View[n]" command to save views from a script; many small bug fixes (configure tests for libpng, handling of erroneous options, multi time step scalar prism drawings, copy of surface mesh attributes, etc.). 1.47 (Nov 12, 2003): fixed extrusion of surfaces defined by only two curves; new syntax to retrieve point coordinates and indices of entities created through geometrical transformations; new PDF and compressed PostScript output formats; fixed numbering of elements created with "Extrude Point/Line"; use $GMSH_HOME as home directory if defined. 1.46 (Aug 23, 2003): fixed crash for very long command lines; new options for setting the displacement factor and Triangle's parameters + renamed a couple of options to more sensible names (View.VectorType, View.ArrowSize); various small bug fixes; documentation update. 1.45 (Jun 14, 2003): small bug fixes (min/max computation for tensor views, missing physical points in read mesh, "jumping" geometry during interactive manipulation of large models, etc.); variable definition speedup; restored support for second order elements in one- and two-dimensional meshes; documentation updates. 1.44 (Apr 21, 2003): new reference manual; added support for PNG output; fixed small configure script bugs. 1.43 (Mar 28, 2003): fixed solver interface problem on Mac OS X; new option to specify the interactive rotation center (default is now the pseudo "center of gravity" of the object, instead of (0,0,0)). 1.42 (Mar 19, 2003): suppressed the automatic addition of a ".geo" extension if the file given on the command line is not recognized; added missing Layer option for Extrude Point; fixed various small bugs. 1.41 (Mar 04, 2003): Gmsh is now licensed under the GNU General Public License; general code cleanup (indent). 1.40 (Feb 26, 2003): various small bug fixes (mainly GSL-related). 1.39 (Feb 23, 2003): removed all non-free routines; more build system work; implemented Von-Mises tensor display for all element types; fixed small GUI bugs. 1.38 (Feb 17, 2003): fixed custom range selection for 3D iso graphs; new build system based on autoconf; new image reading code to import bitmaps as post-processing views. 1.37 (Jan 25, 2003): generalized smoothing and cuts of post-processing views; better Windows integration (solvers, external editors, etc.); small bug fixes. 1.36 (Nov 20, 2002): enhanced view duplication (one can now use "Duplicata View[num]" in the input file); merged all option dialogs in a new general option window; enhanced discoverability of the view option menus; new 3D point and line display; many small bug fixes and enhancements ("Print" format in parser, post-processing statistics, smooth normals, save window positions, restore default options, etc.). 1.35 (Sep 11, 2002): graphical user interface upgraded to FLTK 1.1 (tooltips, new file chooser with multiple selection, full keyboard navigation, cut/paste of messages, etc.); colors can be now be directly assigned to mesh entities; initial tensor visualization; new keyboard animation (right/left arrow for time steps; up/down arrow for view cycling); new VRML output format for surface meshes; new plugin for spherical elevation plots; new post-processing file format (version 1.2) supporting quadrangles, hexahedra, prisms and pyramids; transparency is now enabled by default for post-processing plots; many small bug fixes (read mesh, ...). 1.34 (Feb 18, 2002): improved surface mesh of non-plane surfaces; fixed orientation of elements in 2D anisotropic algorithm; minor user interface polish and additions (mostly in post-processing options); various small bug fixes. 1.33 (Jan 24, 2002): new parameterizable solver interface (allowing up to 5 user-defined solvers); enhanced 2D aniso algorithm; 3D initial mesh speedup. 1.32 (Oct 04, 2001): new visibility browser; better floating point exception checks; fixed infinite looping when merging meshes in project files; various small clean ups (degenerate 2D extrusion, view->reload, ...). 1.31 (Nov 30, 2001): corrected ellipses; PostScript output update (better shading, new combined PS/LaTeX output format); more interface polish; fixed extra memory allocation in 2D meshes; Physical Volume handling in unv format; various small fixes. 1.30 (Nov 16, 2001): interface polish; fix crash when extruding quadrangles. 1.29 (Nov 12, 2001): translations and rotations can now be combined in extrusions; fixed coherence bug in Extrude Line; various small bug fixes and additions. 1.28 (Oct 30, 2001): corrected the 'Using Progression' attribute for tranfinite meshes to actually match a real geometric progression; new Triangulate plugin; new 2D graphs (space+time charts); better performance of geometrical transformations (warning: the numbering of some automatically created entities has changed); new text primitives in post-processing views (file format updated to version 1.1); more robust mean plane computation and error checks; various other small additions and clean-ups. 1.27 (Oct 05, 2001): added ability to extrude curves with Layers/Recombine attributes; new PointSize/LineWidth options; fixed For/EndFor loops in included files; fixed error messages (line numbers+file names) in loops and functions; made the automatic removal of duplicate geometrical entities optional (Geometry.AutoCoherence=0); various other small bug fixes and clean-ups. 1.26 (Sep 06, 2001): enhanced 2D anisotropic mesh generator (metric intersections); fixed small bug in 3D initial mesh; added alternative syntax for built-in functions (for GetDP compatibility); added line element display; Gmsh now saves all the elements in the mesh if no physical groups are defined (or if Mesh.SaveAll=1). 1.25 (Sep 01, 2001): fixed bug with mixed recombined/non-recombined extruded meshes; Linux versions are now build with no optimization, due to bugs in gcc 2.95.X. 1.24 (Aug 30, 2001): fixed characteristic length interpolation for Splines; fixed edge swapping bug in 3D initial mesh; fixed degenerated case in geometrical extrusion (ruled surface with 3 borders); fixed generation of degenerated hexahedra and prisms for recombined+extruded meshes; added BSplines creation in the GUI; integrated Jonathan Shewchuk's Triangle as an alternative isotropic 2D mesh generator; added AngleSmoothNormals to control sharp edge display with smoothed normals; fixed random crash for lighted 3D iso surfaces. 1.23: fixed duplicate elements generation + non-matching tetrahedra faces in 3D extruded meshes; better display of displacement maps; fixed interactive ellipsis construction; generalized boundary operator; added new explode option for post-processing views; enhanced link view behavior (to update only the changed items); added new default plugins: Skin, Transform, Smooth; fixed various other small bugs (mostly in the post-processing module and for extruded meshes). 1.22 (Aug 03, 2001): fixed (yet another) bug for 2D mesh in the mean plane; fixed surface coherence bug in extruded meshes; new double logarithmic scale, saturate value and smoothed normals option for post-processing views; plugins are now enabled by default; three new experimental statically linked plugins: CutMap (extracts a given iso surface from a 3D scalar map), CutPlane (cuts a 3D scalar map with a plane section), CutSphere (cuts a 3D scalar map with a sphere); various other bug fixes, additions and clean-ups. 1.21 (Jul 25, 2001): fixed more memory leaks; added -opt command line option to parse definitions directly from the command line; fixed missing screen refreshes during contour/surface/volume selection; enhanced string manipulation functions (Sprintf, StrCat, StrPrefix); many other small fixes and clean-ups. 1.20 (Jun 14, 2001): fixed various bugs (memory leaks, functions in included files, solver command selection, ColorTable option, duplicate nodes in extruded meshes (not finished yet), infinite loop on empty views, orientation of recombined quadrangles, ...); reorganized the interface menus; added constrained background mesh and mesh visibility options; added mesh quality histograms; changed default mesh colors; reintegrated the old command-line extrusion mesh generator. 1.19 (May 07, 2001): fixed seg. fault for scalar simplex post-processing; new Solver menu; interface for GetDP solver through sockets; fixed multiple scale alignment; added some options + full option descriptions. 1.18 (Apr 26, 2001): fixed many small bugs and incoherences in post-processing; fixed broken background mesh in 1D mesh generation. 1.17 (Apr 17, 2001): corrected physical points saving; fixed parsing of DOS files (carriage return problems); easier geometrical selections (cursor change); plugin manager; enhanced variable arrays (sublist selection and affectation); line loop check; New arrow display; reduced number of 'fatal' errors + better handling in interactive mode; fixed bug when opening meshes; enhanced File->Open behavior for meshes and post-processing views. 1.16 (Feb 26, 2001): added single/double buffer selection (only useful for Unix versions of Gmsh run from remote hosts without GLX); fixed a bug for recent versions of the opengl32.dll on Windows, which caused OpenGL fonts not to show up. 1.15 (Feb 23, 2001): added automatic visibility setting during entity selection; corrected geometrical extrusion bug. 1.14 (Feb 17, 2001): corrected a few bugs in the GUI (most of them were introduced in 1.13); added interactive color selection; made the option database bidirectional (i.e. scripts now correctly update the GUI); default options can now be saved and automatically reloaded at startup; made some changes to the scripting syntax (PostProcessing.View[n] becomes View[n]; Offset0 becomes OffsetX, etc.); corrected the handling of simple triangular surfaces with large characteristic lengths in the 2D isotropic algorithm; added an ASCII to binary post-processing view converter. 1.13 (Feb 09, 2001): added support for JPEG output on Windows. 1.12: corrected vector lines in the post-processing parsed format; corrected animation on Windows; corrected file creation in scripts on Windows; direct affectation of variable arrays. 1.11 (Feb 07, 2001): corrected included file loading problem. 1.10 (Feb 04, 2001): switched from Motif to FLTK for the GUI. Many small tweaks. 1.00 (Jan 15, 2001): added PPM and YUV output; corrected nested If/Endif; Corrected several bugs for pixel output and enhanced GIF output (dithering, transparency); slightly changed the post-processing file format to allow both single and double precision numbers. 0.999 (Dec 20, 2000): added JPEG output and easy MPEG generation (see t8.geo in the tutorial); clean up of export functions; small fixes; Linux versions are now compiled with gcc 2.95.2, which should fix the problems encountered with Mandrake 7.2. 0.998 (Dec 19, 2000): corrected bug introduced in 0.997 in the generation of the initial 3D mesh. 0.997 (Dec 14, 2000): corrected bug in interactive surface/volume selection; Added interactive symmetry; corrected geometrical extrusion with rotation in degenerated or partially degenerated cases; corrected bug in 2D mesh when meshing in the mean plane. 0.996: arrays of variables; enhanced Printf and Sprintf; Simplified options (suppression of option arrays). 0.995 (Dec 11, 2000): totally rewritten geometrical database (performance has been drastically improved for all geometrical transformations, and most notably for extrusion). As a consequence, the internal numbering of geometrical entities has changed: this will cause incompatibilities with old .geo files, and will require a partial rewrite of your old .geo files if these files made use of geometrical transformations. The syntax of the .geo file has also been clarified. Many additions for scripting purposes. New extrusion mesh generator. Preliminary version of the coupling between extruded and Delaunay meshes. New option and procedural database. All interactive operations can be scripted in the input files. See the last example in the tutorial for an example. Many stability enhancements in the 2D and 3D mesh algorithms. Performance boost of the 3D algorithm. Gmsh is still slow, but the performance becomes acceptable. An average 1000 tetrahedra/second is obtained on a 600Mhz computer for a mesh of one million tetrahedra. New anisotropic 2D mesh algorithm. New (ASCII and binary) post-processing file format and clarified mesh file format. New handling for interactive rotations (trackball mode). New didactic interactive mesh construction (watch the Delaunay algorithm in real time on complex geometries: that's exciting ;-). And many, many bug fixes and cleanups. 0.992 (Nov 13, 2000): corrected recombined extrusion; corrected ellipses; added simple automatic animation of post-processing maps; fixed various bugs. 0.991 (Oct 24, 2000): fixed a serious allocation bug in 2D algorithm, which caused random crashes. All users should upgrade to 0.991. 0.990: bug fix in non-recombined 3D transfinite meshes. 0.989 (Sep 01, 2000): added ability to reload previously saved meshes; some new command line options; reorganization of the scale menu; GIF output. 0.987: fixed bug with smoothing (leading to the possible generation of erroneous 3d meshes); corrected bug for mixed 3D meshes; moved the 'toggle view link' option to Opt->Postprocessing_Options. 0.986: fixed overlay problems; SGI version should now also run on 32 bits machines; fixed small 3d mesh bug. 0.985: corrected colormap bug on HP, SUN, SGI and IBM versions; corrected small initialization bug in postscript output. 0.984: corrected bug in display lists; added some options in Opt->General. 0.983: corrected some seg. faults in interactive mode; corrected bug in rotations; changed default window sizes for better match with 1024x768 screens (default X resources can be changed: see ex03.geo). 0.982: lighting for mesh and post-processing; corrected 2nd order mesh on non plane surfaces; added example 13.
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Gmsh is copyright (C) 1997-2008 Christophe Geuzaine <cgeuzaine at ulg.ac.be> and Jean-Francois Remacle <jean-francois.remacle at uclouvain.be> Major code contributions to Gmsh have been provided by Nicolas Tardieu (help with the GSL and Netgen integration), Stephen Guzik (CGNS integration), Pascale Noyret (MED integration) and Jonathan Lambrechts (Fields). Other code contributors include: David Colignon for new colormaps and lots of testing and bug reports; Patrick Dular for transfinite mesh bug fixes; Laurent Stainier for the eigenvalue solvers and for help with the MacOS port and the tensor display code; Pierre Badel for help with the GSL integration; Marc Ume for the original list code; Matt Gundry for the Plot3d mesh format; Jozef Vesely for help with the Tetgen integration; Koen Hillewaert for high order element mappings and other improvements. The AVL tree code (Common/avl.*) and the YUV image code (Graphics/gl2yuv.*) are copyright (C) 1988-1993, 1995 The Regents of the University of California. Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of the University of California not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. The University of California makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty. The trackball code (Common/Trackball.*) is copyright (C) 1993, 1994, Silicon Graphics, Inc. ALL RIGHTS RESERVED. Permission to use, copy, modify, and distribute this software for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both the copyright notice and this permission notice appear in supporting documentation, and that the name of Silicon Graphics, Inc. not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. The GIF and PPM routines (Graphics/gl2gif.cpp) are based on code copyright (C) 1989, 1991, Jef Poskanzer. Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. This software is provided "as is" without express or implied warranty. The colorbar widget (Fltk/Colorbar_Window.cpp) was inspired by code from the Vis5d program for visualizing five dimensional gridded data sets, copyright (C) 1990-1995, Bill Hibbard, Brian Paul, Dave Santek, and Andre Battaiola. This version of Gmsh may contain code (in the contrib/ANN subdirectory) copyright (C) 1997-2005 University of Maryland and Sunil Arya and David Mount: check the configuration options. This version of Gmsh may contain code (in the contrib/MathEval subdirectory) based on GNU libmatheval, copyright (C) 1999, 2002, 2003 Free Software Foundation, Inc: check the configuration options. This version of Gmsh may contain code (in the contrib/Netgen subdirectory) copyright (C) 1994-2004, Joachim Sch"oberl: check the configuration options. This version of Gmsh may contain code (in the contrib/Tetgen subdirectory) copyright (C) 2002, 2004, 2005, 2006 Hang Si: check the configuration options. This version of Gmsh may contain code (in the contrib/Metis subdirectory) written by George Karypis (karypis at cs.umn.edu), copyright (C) 1998, Regents of the University of Minnesota: check the configuration options. This version of Gmsh may contain code (in the contrib/NativeFileChooser subdirectory), copyright (C) 2004 by Greg Ercolano: check the configuration options. Special thanks to Bill Spitzak, Michael Sweet, Matthias Melcher and others for the Fast Light Tool Kit on which Gmsh's GUI is based. See http://www.fltk.org for more info on this excellent object-oriented, cross-platform toolkit. Special thanks also to EDF for funding the OpenCascade integration. Thanks to the following folks who have contributed by providing fresh ideas on theoretical or programming topics, who have sent patches, requests for changes or improvements, or who gave us access to exotic machines for testing Gmsh: Juan Abanto, Olivier Adam, Guillaume Alleon, Eric Bechet, Laurent Champaney, Pascal Dupuis, Philippe Geuzaine, Johan Gyselinck, Francois Henrotte, Benoit Meys, Nicolas Moes, Osamu Nakamura, Chad Schmutzer, Jean-Luc Fl'ejou, Xavier Dardenne, Christophe Prud'homme, Sebastien.Clerc, Jose Miguel Pasini, Philippe Lussou, Jacques Kools, Bayram Yenikaya, Peter Hornby, Krishna Mohan Gundu, Christopher Stott, Timmy Schumacher, Carl Osterwisch, Bruno Frackowiak, Philip Kelleners, Romuald Conty, Ruth Sabariego, Renaud Sizaire, Michel Benhamou, Emilie Marchandise, Tom De Vuyst.
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install-info /usr/info/gmsh.info /usr/info/dir
.
You will then be able to access the documentation with the command
info gmsh
. Note that particular sections (`nodes') can be accessed
directly. For example, info gmsh surfaces
or info gmsh surf
will take you directly to 3.1.3 Surfaces.
.emacs
file: (setq auto-mode-alist (append '(("\\.geo$"
. c++-mode)) auto-mode-alist))
.
General.OptionsFileName
(usually `.gmsh-options' in your home directory) or use the
`Restore default options' button in `Tools->Options->General->Output'.
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$Id: FAQ.txt,v 1.1 2008-07-11 15:55:52 geuzaine Exp $ This is the Gmsh FAQ ******************************************************************** Section 1: The basics * 1.1 What is Gmsh? Gmsh is an automatic three-dimensional finite element mesh generator with built-in pre- and post-processing facilities. Its design goal is to provide a simple meshing tool for academic problems with parametric input and advanced visualization capabilities. * 1.2 What are the terms and conditions of use? Gmsh is distributed under the terms of the GNU General Public License. See the file 'doc/LICENSE' for more information, or go to the GNU foundation's web site at http://www.gnu.org. * 1.3 What does 'Gmsh' mean? Nothing ;-) (Note that in the US, people tend to pronounce 'Gmsh' as 'Gee-mesh'. Yeehaa!) * 1.4 Where can I find more information? http://www.geuz.org/gmsh/ is the primary location to obtain information about Gmsh. You will for example find a complete reference manual as well as a searchable archive of the Gmsh mailing list (gmsh@geuz.org) on this webpage. ******************************************************************** Section 2: Installation * 2.1 Which OSes does Gmsh run on? Gmsh is known to run on Windows 95/98/NT/2000/XP, Linux, Mac OS X, Compaq Tru64 Unix (aka OSF1, aka Digital Unix), Sun OS, IBM AIX, SGI IRIX, FreeBSD and HP-UX. It should compile on any Unix-like operating system, provided that you have access to a recent C and C++ compiler. * 2.2 Are there additional requirements to run Gmsh? You should have the OpenGL libraries installed on your system, and in the path of the library loader. A free replacement for OpenGL can be found at http://www.mesa3d.org. * 2.3 What do I need to compile Gmsh from the sources? You need a C and a C++ compiler (e.g. the GNU compilers gcc and g++) as well as the GSL (version 1.2 or higher; freely available from http://sources.redhat.com/gsl/) and FLTK (version 1.1.x, configured with OpenGL support; freely available from http://www.fltk.org). * 2.4 How do I compile Gmsh? Just type './configure; make; make install'. If you change some configuration options (type './configure --help' to get the list of all available choices), don't forget to do 'make clean' before rebuilding Gmsh. ******************************************************************** Section 3: General problems * 3.1 Gmsh (from a binary distribution) complains about missing libraries. Try 'ldd gmsh' (or 'otool -L gmsh' on Mac OS X) to check if all the required shared libraries are installed on your system. If not, install them. If it still doesn't work, recompile Gmsh from the sources. * 3.2 Gmsh keeps re-displaying its graphics when other windows partially hide the graphical window. Disable opaque move in your window manager. * 3.3 The graphics display very slowly. Are you are executing Gmsh from a remote host (via the network) without GLX? You should turn double buffering off (with the '-nodb' command line option). * 3.4 There is an ugly "ghost triangulation" in the vector PostScript/PDF files generated by Gmsh! No, there isn't. This "ghost triangulation" is due to the fact that most PostScript previewers nowadays antialias the graphic primitives when they display the page on screen. (For example, in gv, you can disable antialising with the 'State->Antialias' menu.) You should not see this ghost triangulation in the printed output (on paper). * 3.5 How can I save GIF, JPEG, ..., images? Just choose the appropriate format in 'File->Save As'. * 3.6 How can I save MPEG, AVI, ..., animations? See question 7.9. ******************************************************************** Section 4: Geometry module * 4.1 Does Gmsh support NURBS curves/surfaces? Yes, but only via STEP, IGES or BREP model import (not in .geo files). * 4.2 Gmsh is very slow when I use many transformations (Translate, Rotate, Symmetry, Extrude, etc. ). What's wrong? The default behavior of Gmsh is to check and suppress all duplicate entities (points, lines and surfaces) each time a transformation command is issued. This can slow down things a lot if many transformations are performed. There are two solutions to this problem: - you may save the unrolled geometry in another file (e.g. with gmsh file.geo -0), and use this new file for subsequent computations; - or you may set the 'Geometry.AutoCoherence' option to 0. This will prevent any automatic duplicate check/replacement. If you still need to remove the duplicates entities, simply add 'Coherence;' at strategic locations in your geo files (e.g. before the creation of line loops, etc.). * 4.3 How can I display only selected parts of my model? Use 'Tool->Visibility'. There are three main modes: 'Elementary entities', in which the selections will apply to elementary geometrical entities; 'Physical groups', in which the selections will apply to physical entities; and 'Mesh partitions', in which the selections will apply to mesh partitions. If the 'Recursive' option is set, selecting an entity also selects all its boundaries, recursively. For example, if 'Recursive' is set, selecting a surface will automatically select its boundary curves, as well as the boundaries of these curves (i.e., points). In the 'Browser' tab, you can select which entities to show or hide in a list (several entities can be selected at once by dragging the mouse or by holding the Ctrl or Shift keys while clicking). In the 'Numerical input' tab, you can choose which entities to show or hide by explicitly specifying their identification tags. In the 'Interactive' tab, you can hide/show entities using the mouse. 4.4 When compiled with OpenCascade support, Gmsh crashes at startup Try changing these environment variables, which govern how OpenCascade allocates memory: export MMGT_OPT=0 export MMGT_MMAP=0 4.5 Can I edit STEP/IGES/BRep models? Not yet. At the moment you can only change characteristic lengths and define physical groups. The easiest way to do this is to merge the model in a .geo file using 'Merge "file.step";' and add the relevant scripting command after that. We plan to add more advanced editing features in the future (to delete entities, to create "mixed" surfaces and volumes, to export in .geo format, etc.). ******************************************************************** Section 5: Mesh module * 5.1 What should I do when the 2D unstructured algorithm fails? Verify that the 1D mesh does not self-intersect. If it does, use a smaller characteristic length. If it doesn't, send us a bug report (including your geometry). * 5.2 What should I do when the 3D unstructured algorithm fails? Try the other 3D algorithms (Tool->Options->Mesh->General->3D algorithm). If none works, try to adapt the characteristic lengths in your input file so that the surface mesh better matches the geometrical details of the model. If nothing works, send us a bug report (including your geometry). * 5.3 The quality of the elements generated by the 3D algorithm is very bad. Use 'Optimize quality' in the mesh menu. * 5.4 Non-recombined 3D extruded meshes sometimes fail. The swapping algorithm is not very clever at the moment. Try to change the surface mesh a bit, or recombine your mesh to generate prisms or hexahedra instead of tetrahedra. * 5.5 Does Gmsh automatically couple unstructured tetrahedral meshes and structured hexahedral meshed using pyramids? No. We need you help to implement this. * 5.6 Can I explicitly assign region numbers to extruded layers? No, this feature has been removed in Gmsh 2.0. You must use the standard entity number instead. * 5.7 Did you remove the elliptic mesh generator in Gmsh 2.0? Yes. You can achieve the same result by using the transfinite algorithm with smoothing (e.g., with "Mesh.Smoothing = 10"). * 5.8 Does Gmsh support curved elements? Yes, Gmsh can generate both 1st order and 2nd order elements. To generate second order elements, click on 'Second order' in the mesh menu after the mesh is completed. To always generate 2nd order elements, select 'Generate second order elements' in the mesh option panel. From the command line, you can also use '-order 2'. * 5.9 Can I import an existing surface mesh in Gmsh and use it to build a 3D mesh? Yes, you can import a surface mesh in any one of the supported mesh file formats, define a volume, and mesh it. For an example see 'demos/sphere-discrete.geo'. * 5.10 How do I define boundary conditions or material properties in Gmsh? By design, Gmsh does not try to incorporate every possible definition of boundary conditions or material properties--this is a job best left to the solver. Instead, Gmsh provides a simple mechanism to tag groups of elements, and it is up to the solver to interpret these tags as boundary conditions, materials, etc. Associating tags with elements in Gmsh is done by defining Physical entities (Physical Points, Physical Lines, Physical Surfaces and Physical Volumes). See the reference manual as well as the tutorials (in particular 'tutorial/t1.geo') for a detailed description and some examples. * 5.11 How can I display only the mesh associated with selected geometrical entities? See question 4.3. * 5.12 How can I "explore" a mesh (for example, to see inside a complex structure)? You can use 'Tools->Clipping Planes' to clip the region of interest. You can define up to 6 clipping planes in Gmsh (i.e., enough to define a "cube" inside your model) and each plane can clip either the geometry, the mesh, the post-processing views, or any combination of the above. The clipping planes are defined using the four coefficients A,B,C,D of the equation A*x+B*y+C*y+D=0, which can be adjusted interactively by dragging the mouse in the input fields. There is also one additional clipping plane available for "cutting" only the mesh (by keeping entire elements), in 'Tools->Options->Mesh->Cutting'. * 5.13 What is the signification of Rho, Eta and Gamma in Tools->Statistics? They measure the quality of the tetrahedra in a mesh: Gamma ~ inscribed_radius / circumscribed_radius Eta ~ volume^(2/3) / sum_edge_length^2 Rho ~ min_edge_length / max_edge_length For the exact definitions, see Geo/MElement.cpp. The graphs plot the the number of elements vs the quality measure. ******************************************************************** Section 6: Solver module * 6.1 How do I integrate my own solver with Gmsh? If you want to simply launch a program from within Gmsh, just edit the options to define your solver commands (e.g. Solver.Name0, Solver.Executable0, etc.), and set the ClientServer option to zero (e.g. Solver.ClientServer0 = 0). If you want your solver to interact with Gmsh (for error messages, option definitions, post-processing, etc.), you will need to link your solver with the GmshClient routines and add the appropriate function calls inside your program. You will of course also need to define your solver commands in an option file, but this time you should set the ClientServer variable to 1 (e.g. Solver.ClientServer = 1). C, C++, Perl and Python solver examples are available in the source distribution in the 'utils/solvers' directory. * 6.2 On Windows, Gmsh does not seem to find the solver executable. What's wrong? The solver executable (for example, 'getdp.exe') has to be in your path. If it is not, simply go to the solver options (the second tab in the Solver dialog) and specify its location in the 'Executable' field. * 6.3 Can I launch Gmsh from my solver (instead of launching my solver from Gmsh) in order to monitor a solution? Sure. The simplest (but rather crude) approach if to re-launch Gmsh everytime you want to visualize something (a simple C program showing how to do this is given in 'utils/misc/callgmsh.c'). A better approach is to modify your program so that it can communicate with Gmsh over a socket (see question 6.1 above; you can skip the option file creation). Then select 'Always listen to incoming connection requests' in the solver option panel (or run gmsh with the '-listen' command line option) and Gmsh will always listen for your program on the Solver.SocketName socket. ******************************************************************** Section 7: Post-processing module * 7.1 How do I compute a section of a plot? Use 'Tools->Plugins->Cut Plane'. * 7.2 Can I save an isosurface to a file? Yes: first run 'Tools->Plugins->Cut Map' to extract the isosurface, then use 'View->Save As' to save the new view. * 7.3 Can Gmsh generate isovolumes? Yes, with the CutMap plugin (set the ExtractVolume option to -1 or 1 to extract the negative or positive levelset). * 7.4 How do I animate my plots? If the views contain multiple time steps, you can press the 'play' button at the bottom of the graphic window, or change the time step by hand in the view option panel. You can also use the left and right arrow keys on your keyboard to change the time step in all visible views in real time. If you want to loop through different views instead of time steps, you can use the 'Loop through views instead of time steps' option in the view option panel, or use the up and down arrow keys on your keyboard. * 7.5 How do I visualize a deformed mesh? Load a vector view containing the displacement field, and set 'Vector display' to 'Displacement' in View->Options->Aspect. If the displacement is too small (or too large), you can scale it with the 'Displacement factor' option. (Remember that you can drag the mouse in all numeric input fields to slide the value!) Another option is to use the "general transformation expressions" (in View->Options->Offset) on a scalar view, with the displacement map selected as the data source. * 7.6 Can I visualize a field on a deformed mesh? Yes, there are several ways to do that. The easiest is to load two views: the first one containing a displacement field (a vector view that will be used to deform the mesh), and the second one containing the field you want to display (this view has to contain the same number of elements as the displacement view). You should then set 'Vector display' to 'Displacement' in the first view, as well as set 'Data source' to point to the second view. (You might want to make the second view invisible, too. If you want to amplify or decrease the amount of deformation, just modify the 'Displacement factor' option.) Another solution is to use the 'General transformation expressions' (in 'View->Options->Offset') on the field you want to display, with the displacement map selected as the data source. And yet another solution is to use the Warp plugin. * 7.7 Can I color the arrows representing a vector field with data from a scalar field? Yes: load both the vector and the scalar fields (the two views must have the same number of elements) and, in the vector field options, select the scalar view in 'Data source'. * 7.8 Can I color isovalue surfaces with data from another scalar view? Yes, using either the CutMap plugin (with the 'dView' option) or the Evaluate plugin. * 7.9 Is there a way to save animations? Yes, using scripts. Have a look at 'tutorial/t8.geo' or 'demos/anim.script' for some examples. * 7.10 Is there a way to visualize only certain components of vector/tensor fields? Yes, using 'Tools->Plugins->Extract'. * 7.11 Can I do arithmetic operations on a view? Can I perform operations involving different views? Yes, with the Evaluate plugin. * 7.12 Some plugins seem to create empty views. What's wrong? There can be several reasons: - the plugin might be written for specific element types only (for example, only for scalar triangles or tetrahedra). In that case, you should transform your view before running the plugin (you can use Plugin(DecomposeinSimplex) to transform all quads, hexas, prisms and pyramids into triangles and tetrahedra). - the plugin might expect a mesh while all you provide is a point cloud. In 2D, you can use Plugin(Triangulate) to transform a point cloud into a triangulated surface. A 3D version of this plugin is not available yet but it is on our TODO list. - the input parameters are out of range. In any case, you can automatically remove all empty views with 'View->Remove->Empty Views' in the GUI, or with "Delete Empty Views;" in a script. * 7.13 My code generates data "time step by time step", and thus cannot easily output Gmsh's multi-time-step post-processing files, where the values for all the time steps are given per element. How can I use Gmsh's post-processor in this situation? Just create one view for each time step: Gmsh can handle an arbitrary number of views and it can deal with these separate views as efficiently as with a single multi-time-step view. The only disadvantage is that the total amount of disk space used is greater (since the node data is repeated for each time step). In practice, depending on the size of the data set, you may want to store all the views in a single file or create one separate file for each view, which you can then load selectively (and thus reduce the memory required for the analysis). In any case you can use 'Tools->Options->Post-processing->View links' to apply options to multiple views at once, and the up and down arrow keys to loop through (animate) the views (instead of the left and right arrow keys for multi-time-step views). Also note that if all the views are based on the same grid, Gmsh can combine the separate views into a multi-time-step view by using the 'View->Combine->Time Steps' menu, or by using the '-combine' command line option. * 7.14 How can I see "inside" a complicated post-processing view? See question 5.12. When viewing 3D scalar fields, you can also modify the colormap ('Tools->Options->View->Map') to make the iso-surfaces "transparent": either by holding 'Ctrl' while dragging the mouse to draw the alpha channel by hand, or by using the 'a', 'Ctrl+a', 'p' and 'Ctrl+p' keyboard shortcuts. Yet another (destructive) option is to use the ExtractVolume option in the CutSphere or CutPlane plugins. * 7.15 I am loading a valid 3D scalar view but Gmsh does not display anything! In versions < 1.61, the default drawing mode for 3D scalar views was to draw iso-surfaces. If your data set was constant per element, Gmsh would not draw anything (a fix for this would be to run Plugin(Smooth), which would average the data on the nodes of the grid)... This behavior has changed in version 1.61, and Gmsh now draws the solution on the boundary of the elements by default. Iso-surfaces are of course still available by setting 'Intervals type' to 'Iso-values' in 'Tools->Options->View->Range'. Note that the most efficient way to visualize the dataset on the boundary of the elements is to run Plugin(Skin) on the view: this will extract the boundary of the dataset and only draw the data on this boundary.
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Gmsh is provided under the terms of the GNU General Public License (GPL) with the following exception:
The copyright holders of Gmsh give you permission to combine Gmsh with code included in the standard release of Triangle (written by Jonathan Shewchuk), TetGen (written by Hang Si) and Netgen (written by Joachim Sch"oberl) under their respective licenses. You may copy and distribute such a system following the terms of the GNU GPL for Gmsh and the licenses of the other code concerned, provided that you include the source code of that other code when and as the GNU GPL requires distribution of source code.
Note that people who make modified versions of Gmsh are not obligated to grant this special exception for their modified versions; it is their choice whether to do so. The GNU General Public License gives permission to release a modified version without this exception; this exception also makes it possible to release a modified version which carries forward this exception.
End of exception.
Copyright © 1989, 1991 Free Software Foundation, Inc. 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. |
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For example, in three dimensions:
Note that mixing structured volume grids with unstructured volume grids generated with the default 3D isotropic Delaunay algorithm can result, in certain cases, to non-conform surface meshes on their shared boundary. If this happens, you may consider using the Netgen algorithm for the unstructured part.
The affectation operators are introduced in 2.6 General commands.
For compatibility with GetDP
(http://www.geuz.org/getdp/), parentheses can be replaced by brackets
[]
.
For compatibility purposes, the behavior
of newl
, news
, newv
and newreg
can be modified
with the Geometry.OldNewReg
option (see section 3.2 Geometry options).
This behaviour was introduced in Gmsh 2.0. In older versions, both the elementary and the physical region numbers would be set to the identification number of the elementary region.
Nearly all the interactive commands have shortcuts: see 8.5 Keyboard shortcuts, or select `Help->Keyboard Shortcuts' in the menu.
If you compile Gmsh without
the graphical user interface, i.e., with ./configure --disable-gui
,
this is the only mode you have access to.
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[Top] | [Contents] | [Index] | [ ? ] |
Copying conditions
1. Overview
2. General tools
3. Geometry module
4. Mesh module
5. Solver module
6. Post-processing module
7. Tutorial
8. Running Gmsh
9. File formats
10. Programming notes
11. Bugs, versions and credits
A. Tips and tricks
B. Frequently asked questions
C. License
Concept index
Syntax index
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