Graphviz  2.41.20170921.2350
inpoly.c
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1 /* $Id$ $Revision$ */
2 /* vim:set shiftwidth=4 ts=8: */
3 
4 /*************************************************************************
5  * Copyright (c) 2011 AT&T Intellectual Property
6  * All rights reserved. This program and the accompanying materials
7  * are made available under the terms of the Eclipse Public License v1.0
8  * which accompanies this distribution, and is available at
9  * http://www.eclipse.org/legal/epl-v10.html
10  *
11  * Contributors: See CVS logs. Details at http://www.graphviz.org/
12  *************************************************************************/
13 
14 /*
15  * in_poly
16  *
17  * Test if a point is inside a polygon.
18  * The polygon must be convex with vertices in CW order.
19  */
20 
21 #include <stdlib.h>
22 #include "vispath.h"
23 #include "pathutil.h"
24 
25 #ifdef DMALLOC
26 #include "dmalloc.h"
27 #endif
28 
29 int in_poly(Ppoly_t poly, Ppoint_t q)
30 {
31  int i, i1; /* point index; i1 = i-1 mod n */
32  int n;
33  Ppoint_t *P;
34 
35  P = poly.ps;
36  n = poly.pn;
37  for (i = 0; i < n; i++) {
38  i1 = (i + n - 1) % n;
39  if (wind(P[i1],P[i],q) == 1) return FALSE;
40  }
41  return TRUE;
42 }
int pn
Definition: pathgeom.h:36
int in_poly(Ppoly_t argpoly, Ppoint_t q)
Definition: inpoly.c:29
int wind(Ppoint_t a, Ppoint_t b, Ppoint_t c)
Definition: visibility.c:65
Ppoint_t * ps
Definition: pathgeom.h:35
Definition: pathgeom.h:26
#define FALSE
Definition: cgraph.h:35
#define TRUE
Definition: cgraph.h:38