Vlib/poly.c File Reference

Vector library - polygon related fns. More...

#include <math.h>
#include <stdlib.h>
#include <grass/vector.h>
#include <grass/linkm.h>
#include <grass/glocale.h>

Include dependency graph for Vlib/poly.c:

Go to the source code of this file.

Functions
int	Vect__intersect_y_line_with_poly (const struct line_pnts *, double, struct line_pnts *)
int	Vect__intersect_x_line_with_poly (const struct line_pnts *, double, struct line_pnts *)
int	Vect_get_point_in_area (struct Map_info *Map, int area, double *X, double *Y)
	Get point inside area and outside all islands. More...
int	Vect_get_point_in_poly (const struct line_pnts *Points, double *X, double *Y)
	Get point inside polygon. More...
int	Vect_find_poly_centroid (const struct line_pnts *points, double *cent_x, double *cent_y)
	Get centroid of polygon. More...
int	Vect_get_point_in_poly_isl (const struct line_pnts *Points, const struct line_pnts **IPoints, int n_isles, double *att_x, double *att_y)
	Get point inside polygon but outside the islands specifiled in IPoints. More...
int	Vect_point_in_poly (double X, double Y, const struct line_pnts *Points)
	Determines if a point (X,Y) is inside a polygon. More...
int	Vect_point_in_area_outer_ring (double X, double Y, struct Map_info *Map, int area, struct bound_box *box)
	Determines if a point (X,Y) is inside an area outer ring. Islands are not considered. More...
int	Vect_point_in_island (double X, double Y, struct Map_info *Map, int isle, struct bound_box *box)
	Determines if a point (X,Y) is inside an island. More...

Detailed Description

Vector library - polygon related fns.

Higher level functions for reading/writing/manipulating vectors.

(C) 2001-2009 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.

Author

Original author CERL, probably Dave Gerdes or Mike Higgins.

Update to GRASS 5.7 Radim Blazek and David D. Gray.

Definition in file Vlib/poly.c.

Function Documentation

Vect__intersect_x_line_with_poly()

int Vect__intersect_x_line_with_poly	(	const struct line_pnts *	Points,
		double	x,
		struct line_pnts *	Inter
	)

Definition at line 169 of file Vlib/poly.c.

Vect__intersect_y_line_with_poly()

int Vect__intersect_y_line_with_poly	(	const struct line_pnts *	Points,
		double	y,
		struct line_pnts *	Inter
	)

Definition at line 126 of file Vlib/poly.c.

Vect_find_poly_centroid()

int Vect_find_poly_centroid	(	const struct line_pnts *	points,
		double *	cent_x,
		double *	cent_y
	)

Get centroid of polygon.

Parameters

	points	polygon
[out]	cent_x,cent_y	centroid coordinates

Returns

0 on success

-1 on error

Definition at line 355 of file Vlib/poly.c.

References line_pnts::n_points, line_pnts::x, and line_pnts::y.

Vect_get_point_in_area()

int Vect_get_point_in_area	(	struct Map_info *	Map,
		int	area,
		double *	X,
		double *	Y
	)

Get point inside area and outside all islands.

Take a line and intersect it with the polygon and any islands. sort the list of X values from these intersections. This will be a list of segments alternating IN/OUT/IN/OUT of the polygon. Pick the largest IN segment and take the midpoint.

Parameters

	Map	vector map
	area	area id
[out]	X,Y	point coordinateds

Returns

0 on success

-1 on error

Definition at line 55 of file Vlib/poly.c.

Vect_get_point_in_poly()

int Vect_get_point_in_poly	(	const struct line_pnts *	Points,
		double *	X,
		double *	Y
	)

Get point inside polygon.

This does NOT consider ISLANDS!

Parameters

	Points	polygon
[out]	X,Y	point coordinates

Returns

0 on success

-1 on error

Definition at line 208 of file Vlib/poly.c.

Vect_get_point_in_poly_isl()

int Vect_get_point_in_poly_isl	(	const struct line_pnts *	Points,
		const struct line_pnts **	IPoints,
		int	n_isles,
		double *	att_x,
		double *	att_y
	)

Get point inside polygon but outside the islands specifiled in IPoints.

Take a line and intersect it with the polygon and any islands. sort the list of X values from these intersections. This will be a list of segments alternating IN/OUT/IN/OUT of the polygon. Pick the largest IN segment and take the midpoint.

Parameters

	Points	polygon (boundary)
	IPoints	isles (list of isle boundaries)
	n_isles	number of isles
[out]	att_x,att_y	point coordinates

Returns

0 on success

-1 on error

Definition at line 449 of file Vlib/poly.c.

Vect_point_in_area_outer_ring()

int Vect_point_in_area_outer_ring	(	double	X,
		double	Y,
		struct Map_info *	Map,
		int	area,
		struct bound_box *	box
	)

Determines if a point (X,Y) is inside an area outer ring. Islands are not considered.

Parameters

X,Y	point coordinates
Map	vector map
area	area id
box	area bounding box

Returns

0 - outside

1 - inside

2 - on the boundary

Definition at line 854 of file Vlib/poly.c.

Vect_point_in_island()

int Vect_point_in_island	(	double	X,
		double	Y,
		struct Map_info *	Map,
		int	isle,
		struct bound_box *	box
	)

Determines if a point (X,Y) is inside an island.

Parameters

X,Y	point coordinates
Map	vector map
isle	isle id
box	isle bounding box

Returns

0 - outside

1 - inside

2 - on the boundary

Definition at line 923 of file Vlib/poly.c.

Vect_point_in_poly()

int Vect_point_in_poly	(	double	X,
		double	Y,
		const struct line_pnts *	Points
	)

Determines if a point (X,Y) is inside a polygon.

Parameters

X,Y	point coordinates
Points	polygon

Returns

0 - outside

1 - inside

2 - on the boundary

Definition at line 824 of file Vlib/poly.c.