1
0
mirror of git://projects.qi-hardware.com/cae-tools.git synced 2024-12-23 03:36:27 +02:00
cae-tools/poly2d/v2d_line_distance.c
2015-01-18 20:45:44 -03:00

35 lines
797 B
C

/*
* v2d_line_distance.c - Calculate the distance between a point and a line
*
* Written 2012 by Werner Almesberger
* Copyright 2012 Werner Almesberger
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*/
#include <math.h>
#include "poly2d.h"
/*
* We use formula (14) from
* http://mathworld.wolfram.com/Point-LineDistance2-Dimensional.html
* but keep the sign.
*/
double v2d_line_distance(const struct v2d *a, const struct v2d *b,
const struct v2d *p)
{
double ax, ay;
ax = b->x-a->x;
ay = b->y-a->y;
return (ax*(a->y-p->y)-ay*(a->x-p->x))/hypot(ax, ay);
}