Vector library - intersection (lower level functions) More...

#include <stdlib.h>
#include <math.h>
#include <grass/gis.h>
#include "e_intersect.h"

Include dependency graph for e_intersect.c:

Macros
#define	SWAP(a, b)

#define	D ((ax2 - ax1) * (by1 - by2) - (ay2 - ay1) * (bx1 - bx2))

#define	DA ((bx1 - ax1) * (by1 - by2) - (by1 - ay1) * (bx1 - bx2))

#define	DB ((ax2 - ax1) * (by1 - ay1) - (ay2 - ay1) * (bx1 - ax1))

#define	N 52 /* double's mantisa size in bits */

Functions
int	segment_intersection_2d_tol (double ax1, double ay1, double ax2, double ay2, double bx1, double by1, double bx2, double by2, double x1, double y1, double x2, double y2, double tol)

int	segment_intersection_2d (double ax1, double ay1, double ax2, double ay2, double bx1, double by1, double bx2, double by2, double x1, double y1, double x2, double y2)

int	almost_equal (double a, double b, int bits)

Detailed Description

Vector library - intersection (lower level functions)

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: Rewritten by Rosen Matev (Google Summer of Code 2008)

Definition in file e_intersect.c.

Macro Definition Documentation

◆ D

#define D ((ax2 - ax1) * (by1 - by2) - (ay2 - ay1) * (bx1 - bx2))

Definition at line 29 of file e_intersect.c.

◆ DA

#define DA ((bx1 - ax1) * (by1 - by2) - (by1 - ay1) * (bx1 - bx2))

Definition at line 30 of file e_intersect.c.

◆ DB

#define DB ((ax2 - ax1) * (by1 - ay1) - (ay2 - ay1) * (bx1 - ax1))

Definition at line 31 of file e_intersect.c.

◆ N

#define N 52 /* double's mantisa size in bits */

Definition at line 926 of file e_intersect.c.

◆ SWAP

#define SWAP	(	a,
		b
	)

Value:

    {                 \
        double t = a; \
        a = b;        \
        b = t;        \
    }

Definition at line 23 of file e_intersect.c.

Function Documentation

◆ almost_equal()

int almost_equal	(	double	a,
		double	b,
		int	bits
	)

Definition at line 928 of file e_intersect.c.

References b, and N.

◆ segment_intersection_2d()

int segment_intersection_2d	(	double	ax1,
		double	ay1,
		double	ax2,
		double	ay2,
		double	bx1,
		double	by1,
		double	bx2,
		double	by2,
		double *	x1,
		double *	y1,
		double *	x2,
		double *	y2
	)

Definition at line 692 of file e_intersect.c.

References D, DA, DB, G_debug(), G_warning(), MAX, MIN, and SWAP.

Referenced by find_all_intersections().

◆ segment_intersection_2d_tol()

int segment_intersection_2d_tol	(	double	ax1,
		double	ay1,
		double	ax2,
		double	ay2,
		double	bx1,
		double	by1,
		double	bx2,
		double	by2,
		double *	x1,
		double *	y1,
		double *	x2,
		double *	y2,
		double	tol
	)

Definition at line 361 of file e_intersect.c.

References FEQUAL, FZERO, G_debug(), G_warning(), MAX, MIN, and t.

Macros

Functions