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/* Libart_LGPL - library of basic graphic primitives
* Copyright (C) 1999 Raph Levien
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include "art_svp_point.h"
#include <math.h>
#include "art_misc.h"
#include "art_svp.h"
/* Determine whether a point is inside, or near, an svp. */
/* return winding number of point wrt svp */
/**
* art_svp_point_wind: Determine winding number of a point with respect to svp.
* @svp: The svp.
* @x: The X coordinate of the point.
* @y: The Y coordinate of the point.
*
* Determine the winding number of the point @x, @y with respect to @svp.
*
* Return value: the winding number.
**/
int
art_svp_point_wind (ArtSVP *svp, double x, double y)
{
int i, j;
int wind = 0;
for (i = 0; i < svp->n_segs; i++)
{
ArtSVPSeg *seg = &svp->segs[i];
if (seg->bbox.y0 > y)
break;
if (seg->bbox.y1 > y)
{
if (seg->bbox.x1 < x)
wind += seg->dir ? 1 : -1;
else if (seg->bbox.x0 <= x)
{
double x0, y0, x1, y1, dx, dy;
for (j = 0; j < seg->n_points - 1; j++)
{
if (seg->points[j + 1].y > y)
break;
}
x0 = seg->points[j].x;
y0 = seg->points[j].y;
x1 = seg->points[j + 1].x;
y1 = seg->points[j + 1].y;
dx = x1 - x0;
dy = y1 - y0;
if ((x - x0) * dy > (y - y0) * dx)
wind += seg->dir ? 1 : -1;
}
}
}
return wind;
}
/**
* art_svp_point_dist: Determine distance between point and svp.
* @svp: The svp.
* @x: The X coordinate of the point.
* @y: The Y coordinate of the point.
*
* Determines the distance of the point @x, @y to the closest edge in
* @svp. A large number is returned if @svp is empty.
*
* Return value: the distance.
**/
double
art_svp_point_dist (ArtSVP *svp, double x, double y)
{
int i, j;
double dist_sq;
double best_sq = -1;
for (i = 0; i < svp->n_segs; i++)
{
ArtSVPSeg *seg = &svp->segs[i];
for (j = 0; j < seg->n_points - 1; j++)
{
double x0 = seg->points[j].x;
double y0 = seg->points[j].y;
double x1 = seg->points[j + 1].x;
double y1 = seg->points[j + 1].y;
double dx = x1 - x0;
double dy = y1 - y0;
double dxx0 = x - x0;
double dyy0 = y - y0;
double dot = dxx0 * dx + dyy0 * dy;
if (dot < 0)
dist_sq = dxx0 * dxx0 + dyy0 * dyy0;
else
{
double rr = dx * dx + dy * dy;
if (dot > rr)
dist_sq = (x - x1) * (x - x1) + (y - y1) * (y - y1);
else
{
double perp = (y - y0) * dx - (x - x0) * dy;
dist_sq = perp * perp / rr;
}
}
if (best_sq < 0 || dist_sq < best_sq)
best_sq = dist_sq;
}
}
if (best_sq >= 0)
return sqrt (best_sq);
else
return 1e12;
}
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