[Bf-blender-cvs] SVN commit: /data/svn/bf-blender [44838] trunk/blender/source/blender/ blenlib/intern/math_geom.c: fix [#30529] BMesh: Wrong Indizes of Faces

Campbell Barton ideasman42 at gmail.com
Mon Mar 12 22:09:40 CET 2012


Revision: 44838
          http://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=44838
Author:   campbellbarton
Date:     2012-03-12 21:09:27 +0000 (Mon, 12 Mar 2012)
Log Message:
-----------
fix [#30529] BMesh: Wrong Indizes of Faces

problem was bow-tie quads would add opposite normals together and result in zero vector which was used for projection.
Now is_quad_convex_v3() checks if quad contains 2 faces which point away from eachother when split by either direction.

Theres another fix for this bug which can be done since creating the face can use existing edges in the example given so it wont have to guess which order of verts to use.

Modified Paths:
--------------
    trunk/blender/source/blender/blenlib/intern/math_geom.c

Modified: trunk/blender/source/blender/blenlib/intern/math_geom.c
===================================================================
--- trunk/blender/source/blender/blenlib/intern/math_geom.c	2012-03-12 18:53:22 UTC (rev 44837)
+++ trunk/blender/source/blender/blenlib/intern/math_geom.c	2012-03-12 21:09:27 UTC (rev 44838)
@@ -3058,10 +3058,23 @@
  {
 	float nor[3], nor1[3], nor2[3], vec[4][2];
 	int axis_a, axis_b;
-	
+
 	/* define projection, do both trias apart, quad is undefined! */
+
+	/* strictly speaking this isn't necessarily convex,
+	 * but when try normals point away from eachother
+	 * we don't wan't to make that face */
+	normal_tri_v3(nor1, v2, v3, v4);
+	normal_tri_v3(nor2, v1, v2, v4);
+	if (UNLIKELY(dot_v3v3(nor1, nor2) < 0.0f)) {
+		return FALSE;
+	}
 	normal_tri_v3(nor1, v1, v2, v3);
 	normal_tri_v3(nor2, v1, v3, v4);
+	if (UNLIKELY(dot_v3v3(nor1, nor2) < 0.0f)) {
+		return FALSE;
+	}
+
 	add_v3_v3v3(nor, nor1, nor2);
 
 	axis_dominant_v3(&axis_a, &axis_b, nor);
@@ -3071,7 +3084,7 @@
 
 	vec[2][0]= v3[axis_a]; vec[2][1]= v3[axis_b];
 	vec[3][0]= v4[axis_a]; vec[3][1]= v4[axis_b];
-	
+
 	/* linetests, the 2 diagonals have to instersect to be convex */
-	return (isect_line_line_v2(vec[0], vec[2], vec[1], vec[3]) > 0) ? 1 : 0;
+	return (isect_line_line_v2(vec[0], vec[2], vec[1], vec[3]) > 0) ? TRUE : FALSE;
 }




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