Index: code/renderer/tr_model_iqm.c
===================================================================
--- code/renderer/tr_model_iqm.c	(revision 2147)
+++ code/renderer/tr_model_iqm.c	(working copy)
@@ -92,30 +92,41 @@
 	mat[10] = scale[2] * (1.0f - (xx + yy));
 	mat[11] = trans[2];
 }
-static void JointToMatrixInverse( vec4_t rot, vec3_t scale, vec3_t trans,
-				  float *mat ) {
-	float xx = 2.0f * rot[0] * rot[0];
-	float yy = 2.0f * rot[1] * rot[1];
-	float zz = 2.0f * rot[2] * rot[2];
-	float xy = 2.0f * rot[0] * rot[1];
-	float xz = 2.0f * rot[0] * rot[2];
-	float yz = 2.0f * rot[1] * rot[2];
-	float wx = 2.0f * rot[3] * rot[0];
-	float wy = 2.0f * rot[3] * rot[1];
-	float wz = 2.0f * rot[3] * rot[2];
-
-	mat[ 0] = scale[0] * (1.0f - (yy + zz));
-	mat[ 1] = scale[0] * (xy + wz);
-	mat[ 2] = scale[2] * (xz - wy);
-	mat[ 3] = -DotProduct((mat + 0), trans);
-	mat[ 4] = scale[0] * (xy - wz);
-	mat[ 5] = scale[1] * (1.0f - (xx + zz));
-	mat[ 6] = scale[2] * (yz + wx);
-	mat[ 7] = -DotProduct((mat + 4), trans);
-	mat[ 8] = scale[0] * (xz + wy);
-	mat[ 9] = scale[1] * (yz - wx);
-	mat[10] = scale[2] * (1.0f - (xx + yy));
-	mat[11] = -DotProduct((mat + 8), trans);
+static void Matrix34Invert( float *inMat, float *outMat )
+{
+	vec3_t trans;
+	float lsq;
+
+	trans[0] = inMat[ 3];
+	trans[1] = inMat[ 7];
+	trans[2] = inMat[11];
+
+	outMat[ 0] = inMat[ 0];
+	outMat[ 1] = inMat[ 4];
+	outMat[ 2] = inMat[ 8];
+	lsq = DotProduct(outMat + 0, outMat + 0);
+	outMat[ 0] /= lsq;
+	outMat[ 1] /= lsq;
+	outMat[ 2] /= lsq;
+	outMat[ 3] = -DotProduct(outMat + 0, trans);
+
+	outMat[ 4] = inMat[ 1];
+	outMat[ 5] = inMat[ 5];
+	outMat[ 6] = inMat[ 9];
+	lsq = DotProduct(outMat + 4, outMat + 4);
+	outMat[ 4] /= lsq;
+	outMat[ 5] /= lsq;
+	outMat[ 6] /= lsq;
+	outMat[ 7] = -DotProduct(outMat + 4, trans);
+
+	outMat[ 8] = inMat[ 2];
+	outMat[ 9] = inMat[ 6];
+	outMat[10] = inMat[10];
+	lsq = DotProduct(outMat + 8, outMat + 8);
+	outMat[ 8] /= lsq;
+	outMat[ 9] /= lsq;
+	outMat[10] /= lsq;
+	outMat[11] = -DotProduct(outMat + 8, trans);
 }
 
 /*
@@ -473,7 +484,7 @@
 	mat = jointMats;
 	joint = (iqmJoint_t *)((byte *)header + header->ofs_joints);
 	for( i = 0; i < header->num_joints; i++, joint++ ) {
-		float tmpMat[12];
+		float tmpMat[12], tmpMat2[12];
 
 		JointToMatrix( joint->rotate, joint->scale, joint->translate,
 			       tmpMat );
@@ -488,18 +499,16 @@
 
 		mat += 12;
 
-		// compute the inverse matrix by combining the
-		// inverse scale, rotation and translation
-		JointToMatrixInverse( joint->rotate, joint->scale,
-				      joint->translate, tmpMat );
+		// compute the inverse matrix
+		Matrix34Invert(tmpMat, tmpMat2);
 
 		if( joint->parent >= 0 ) {
 			// premultiply with inverse parent-matrix
-			Matrix34Multiply( tmpMat,
+			Matrix34Multiply( tmpMat2,
 					  jointMats + 2 * 12 * joint->parent + 12,
 					  mat);
 		} else {
-			Com_Memcpy( mat, tmpMat, sizeof(tmpMat) );
+			Com_Memcpy( mat, tmpMat2, sizeof(tmpMat2) );
 		}
 
 		mat += 12;