From: havoc <havoc@d7cf8633-e32d-0410-b094-e92efae38249>
Date: Sun, 25 Jan 2009 17:57:37 +0000 (+0000)
Subject: fix stupid degenerate triangle check, I don't have a clue what I was
X-Git-Tag: xonotic-v0.1.0preview~1923
X-Git-Url: https://git.rm.cloudns.org/?a=commitdiff_plain;h=96ec5538718dce6817757d85f613418ca055e3a7;p=xonotic%2Fdarkplaces.git

fix stupid degenerate triangle check, I don't have a clue what I was
thinking when I wrote it


git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@8671 d7cf8633-e32d-0410-b094-e92efae38249
---

diff --git a/model_shared.c b/model_shared.c
index 911d3fca..381eb71f 100644
--- a/model_shared.c
+++ b/model_shared.c
@@ -2105,23 +2105,20 @@ void Mod_SnapVertices(int numcomponents, int numvertices, float *vertices, float
 int Mod_RemoveDegenerateTriangles(int numtriangles, const int *inelement3i, int *outelement3i, const float *vertex3f)
 {
 	int i, outtriangles;
-	float d, edgedir[3], temp[3];
+	float d, edgedir1[3], edgedir2[3], temp[3];
 	// a degenerate triangle is one with no width (thickness, surface area)
 	// these are characterized by having all 3 points colinear (along a line)
 	// or having two points identical
+	// the simplest check is to calculate the triangle's area
 	for (i = 0, outtriangles = 0;i < numtriangles;i++, inelement3i += 3)
 	{
 		// calculate first edge
-		VectorSubtract(vertex3f + inelement3i[1] * 3, vertex3f + inelement3i[0] * 3, edgedir);
-		if (VectorLength2(edgedir) < 0.0001f)
-			continue; // degenerate first edge (no length)
-		VectorNormalize(edgedir);
-		// check if third point is on the edge (colinear)
-		d = -DotProduct(vertex3f + inelement3i[2] * 3, edgedir);
-		VectorMA(vertex3f + inelement3i[2] * 3, d, edgedir, temp);
-		if (VectorLength2(temp) < 0.0001f)
-			continue; // third point colinear with first edge
-		// valid triangle (no colinear points, no duplicate points)
+		VectorSubtract(vertex3f + inelement3i[1] * 3, vertex3f + inelement3i[0] * 3, edgedir1);
+		VectorSubtract(vertex3f + inelement3i[1] * 3, vertex3f + inelement3i[0] * 3, edgedir2);
+		CrossProduct(edgedir1, edgedir2, temp);
+		if (VectorLength2(temp) < 0.001f)
+			continue; // degenerate triangle (no area)
+		// valid triangle (has area)
 		VectorCopy(inelement3i, outelement3i);
 		outelement3i += 3;
 		outtriangles++;