#include <math.h>
#include <grass/gis.h>
Go to the source code of this file.
Functions | |
int | G_begin_distance_calculations () |
begin distance calculations | |
double | G_distance (double e1, double n1, double e2, double n2) |
distance in meters | |
double | G_distance_between_line_segments (double ax1, double ay1, double ax2, double ay2, double bx1, double by1, double bx2, double by2) |
double | G_distance_point_to_line_segment (double xp, double yp, double x1, double y1, double x2, double y2) |
int G_begin_distance_calculations | ( | ) |
begin distance calculations
Initializes the distance calculations. It is used both for the planimetric and latitude-longitude projections. It returns 2 if the projection is latitude-longitude, 1 if the projection is planimetric, and 0 if the projection doesn't hav e a metric (e.g. imagery.)
void |
Definition at line 28 of file distance.c.
References G_begin_geodesic_distance(), G_database_units_to_meters_factor(), G_get_ellipsoid_parameters(), and G_projection().
double G_distance | ( | double | e1, | |
double | n1, | |||
double | e2, | |||
double | n2 | |||
) |
distance in meters
This routine computes the distance, in meters, from x1,y1 to x2,y2. If the projection is latitude-longitude, this distance is measured along the geodesic. Two routines perform geodesic distance calculations.
x1 | ||
y1 | ||
x2 | ||
y2 |
Definition at line 66 of file distance.c.
References G_geodesic_distance().
Referenced by G_distance_point_to_line_segment().
double G_distance_between_line_segments | ( | double | ax1, | |
double | ay1, | |||
double | ax2, | |||
double | ay2, | |||
double | bx1, | |||
double | by1, | |||
double | bx2, | |||
double | by2 | |||
) |
Definition at line 77 of file distance.c.
References G_distance_point_to_line_segment(), and G_intersect_line_segments().
double G_distance_point_to_line_segment | ( | double | xp, | |
double | yp, | |||
double | x1, | |||
double | y1, | |||
double | x2, | |||
double | y2 | |||
) |
Definition at line 100 of file distance.c.
References G_distance(), and G_intersect_line_segments().
Referenced by G_distance_between_line_segments().