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.

int	Vect_get_point_in_poly (const struct line_pnts Points, double X, double *Y)
	Get point inside polygon.

int	Vect_find_poly_centroid (const struct line_pnts points, double cent_x, double *cent_y)
	Get centroid of polygon.

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.

int	Vect_point_in_poly (double X, double Y, const struct line_pnts *Points)
	Determines if a point (X,Y) is inside a polygon.

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.

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.

Detailed Description

Vector library - polygon related fns.

Higher level functions for reading/writing/manipulating vectors.

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.

References b, line_pnts::n_points, Vect_append_point(), line_pnts::x, and line_pnts::y.

Referenced by Vect_get_point_in_poly_isl().

◆ 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.

References b, line_pnts::n_points, Vect_append_point(), line_pnts::x, and line_pnts::y.

Referenced by Vect_get_point_in_poly_isl().

◆ 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.

Referenced by Vect_get_point_in_poly(), and Vect_get_point_in_poly_isl().

◆ 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.

References G_debug(), G_realloc, NULL, Vect_get_area_isle(), Vect_get_area_num_isles(), Vect_get_area_points(), Vect_get_isle_points(), Vect_get_point_in_poly_isl(), Vect_new_line_struct(), X, and Y.

◆ 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.

References _, G_debug(), G_warning(), link_exit_on_error(), link_init(), link_new(), line_pnts::n_points, NULL, Vect_find_poly_centroid(), Vect_point_in_poly(), X, line_pnts::x, x, and Y.

Referenced by V2_write_line_sfa().

◆ 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.

References G_debug(), G_warning(), max, line_pnts::n_points, Vect__intersect_x_line_with_poly(), Vect__intersect_y_line_with_poly(), Vect_find_poly_centroid(), Vect_new_line_struct(), Vect_point_in_poly(), line_pnts::x, and line_pnts::y.

Referenced by Vect_get_point_in_area().

◆ 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.

References bound_box::E, G_debug(), P_area::lines, bound_box::N, P_area::n_lines, NULL, Vect_new_line_struct(), Vect_read_line(), W, X, and Y.

Referenced by Vect_find_area(), Vect_isle_find_area(), and Vect_point_in_area().

◆ 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.

References bound_box::E, G_debug(), P_isle::lines, bound_box::N, P_isle::n_lines, NULL, Vect_new_line_struct(), Vect_read_line(), W, X, and Y.

Referenced by Vect_find_area(), Vect_find_island(), and Vect_point_in_area().

◆ 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.

References G_debug(), line_pnts::n_points, X, and Y.

Referenced by Vect_get_point_in_poly(), Vect_get_point_in_poly_isl(), and Vect_select_lines_by_polygon().

Functions

Detailed Description

Function Documentation

◆ Vect__intersect_x_line_with_poly()

◆ Vect__intersect_y_line_with_poly()

◆ Vect_find_poly_centroid()

◆ Vect_get_point_in_area()

◆ Vect_get_point_in_poly()

◆ Vect_get_point_in_poly_isl()

◆ Vect_point_in_area_outer_ring()

◆ Vect_point_in_island()

◆ Vect_point_in_poly()