From 6e869eb5e6ff1686a865d2a334ed1f6a2d7915b1 Mon Sep 17 00:00:00 2001
From: lecoanet
Date: Mon, 9 Dec 2002 14:38:04 +0000
Subject: 	* Adaptation de POLY_CONTOUR et POLY_SET pour tenir compte de
 cw. 	* Reprise du code de TestCCW pir qu'il fonctionne mieux.

---
 generic/Geo.c | 36 +++++++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 9 deletions(-)

(limited to 'generic/Geo.c')

diff --git a/generic/Geo.c b/generic/Geo.c
index 2039e77..8cd2edf 100644
--- a/generic/Geo.c
+++ b/generic/Geo.c
@@ -46,17 +46,20 @@ void
 POLY_INIT(ZnPoly	*poly)
 {
   poly->num_contours = 0;
+  poly->contours = NULL;
 }
 
 void
 POLY_CONTOUR1(ZnPoly	*poly,
 	      ZnPoint	*pts,
-	      int	num_pts)
+	      int	num_pts,
+	      ZnBool	cw)
 {
   poly->num_contours = 1;
   poly->contours = &poly->contour1;
   poly->contour1.num_points = num_pts;
   poly->contour1.points = pts;
+  poly->contour1.cw = cw;
 }
 
 void
@@ -65,7 +68,8 @@ POLY_SET(ZnPoly	*poly1,
 {
   POLY_FREE(poly1);
   if (poly2->num_contours == 1) {
-    POLY_CONTOUR1(poly1, poly2->contours[0].points, poly2->contours[0].num_points);
+    POLY_CONTOUR1(poly1, poly2->contours[0].points, poly2->contours[0].num_points,
+		  poly2->contours[0].cw);
     if (poly2->contours != &poly2->contour1) {
       ZnFree(poly2->contours);
     }
@@ -534,7 +538,7 @@ ZnBool
 TestCCW(ZnPoint	*points,
 	int	num_points)
 {
-  ZnPoint	*p, *p_p, *p_n, min;
+  ZnPoint	*p, *p_p=NULL, *p_n=NULL, min;
   ZnReal	xprod;
   int		i, min_index;
   
@@ -563,12 +567,26 @@ TestCCW(ZnPoint	*points,
   p = &points[min_index];
   /*printf("min index %d, prev %d, next %d\n", min_index,
     (min_index+(num_points-1))%num_points, (min_index+1)%num_points);*/
-  p_p = &points[(min_index+(num_points-1))%num_points]; /* min_index-1 */
-  p_n = &points[(min_index+1)%num_points];
-  xprod = ((p_p->x*p->y - p_p->y*p->x) +
-	   (p_p->y*p_n->x - p_p->x*p_n->y) +
-	   (p->x*p_n->y - p->y*p_n->x));
-  return (xprod <= 0.0); /* Should be >= 0 but X11 has Y axis reverted. */
+  /*printf("lower point index %d %d %d\n",
+    (min_index+(num_points-1))%num_points, min_index, (min_index+1)%num_points);*/
+  /*
+   * Try to find preceding and following points that are not
+   * the same as the base point.
+   */
+  for (i = 1; i < num_points; i++) {
+    p_p = &points[(min_index+(num_points-i))%num_points]; /* min_index-1 */
+    if ((p_p->x != p->x) || (p_p->y != p->y)) {
+      break;
+    }
+  }
+  for (i = 1; i < num_points; i++) {
+    p_n = &points[(min_index+i)%num_points];
+    if ((p_p->x != p->x) || (p_p->y != p->y)) {
+      break;
+    }
+  }
+  xprod = ((p->x - p_p->x) * (p_n->y - p->y)) - ((p->y - p_p->y) * (p_n->x - p->x));
+  return (xprod < 0.0); /* Should be > 0 but X11 has Y axis reverted. */
 }
 
 
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