GRASS GIS 8 Programmer's Manual
8.5.0dev(2024)-1d42e580e2
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GIS Library - Distance calculation functions. More...
Go to the source code of this file.
Functions | |
int | G_begin_distance_calculations (void) |
Begin distance calculations. More... | |
double | G_distance (double e1, double n1, double e2, double n2) |
Returns distance in meters. More... | |
double | G_distance_between_line_segments (double ax1, double ay1, double ax2, double ay2, double bx1, double by1, double bx2, double by2) |
Returns distance between two line segments in meters. More... | |
double | G_distance_point_to_line_segment (double xp, double yp, double x1, double y1, double x2, double y2) |
Returns distance between a point and line segment in meters. More... | |
GIS Library - Distance calculation functions.
WARNING: this code is preliminary and may be changed, including calling sequences to any of the functions defined here.
(C) 2001-2009, 2011 by the GRASS Development Team
This program is free software under the GNU General Public License (>=v2). Read the file COPYING that comes with GRASS for details.
Definition in file gis/distance.c.
int G_begin_distance_calculations | ( | void | ) |
Begin distance calculations.
Initializes the distance calculations. It is used both for the planimetric and latitude-longitude projections.
Definition at line 42 of file gis/distance.c.
Referenced by Vect_line_geodesic_distance().
double G_distance | ( | double | e1, |
double | n1, | ||
double | e2, | ||
double | n2 | ||
) |
Returns 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.
e1,n1 | east-north coordinates of first point |
e2,n2 | east-north coordinates of second point |
Definition at line 75 of file gis/distance.c.
References G_geodesic_distance(), PROJECTION_LL, and st.
Referenced by Vect_line_geodesic_distance().
double G_distance_between_line_segments | ( | double | ax1, |
double | ay1, | ||
double | ax2, | ||
double | ay2, | ||
double | bx1, | ||
double | by1, | ||
double | bx2, | ||
double | by2 | ||
) |
Returns distance between two line segments in meters.
ax1,ay1,ax2,ay2 | first segment |
bx1,by1,bx2,by2 | second segment |
Definition at line 91 of file gis/distance.c.
References G_intersect_line_segments(), and x.
double G_distance_point_to_line_segment | ( | double | xp, |
double | yp, | ||
double | x1, | ||
double | y1, | ||
double | x2, | ||
double | y2 | ||
) |
Returns distance between a point and line segment in meters.
xp,yp | point coordinates |
x1,y1 | segment point coordinates |
x2,y2 | segment point coordinates |
Definition at line 117 of file gis/distance.c.