[Bf-blender-cvs] SVN commit: /data/svn/bf-blender [51348] trunk/blender/intern/cycles/util/ util_transform.h: Fix #32844: cycles camera motion blur producing completely blurred frames sometimes.

[Brecht Van Lommel]

Revision: 51348
          http://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=51348
Author:   blendix
Date:     2012-10-15 17:56:40 +0000 (Mon, 15 Oct 2012)
Log Message:
-----------
Fix #32844: cycles camera motion blur producing completely blurred frames sometimes.

Modified Paths:
--------------
    trunk/blender/intern/cycles/util/util_transform.h

Modified: trunk/blender/intern/cycles/util/util_transform.h
===================================================================
--- trunk/blender/intern/cycles/util/util_transform.h	2012-10-15 17:52:09 UTC (rev 51347)
+++ trunk/blender/intern/cycles/util/util_transform.h	2012-10-15 17:56:40 UTC (rev 51348)
@@ -304,10 +304,18 @@
 {
 	float costheta = dot(q1, q2);
 
+	/* rotate around shortest angle */
+	if(costheta < 0.0f) {
+		costheta = -costheta;
+		q1 = -q1;
+	}
+
 	if(costheta > 0.9995f) {
+		/* linear interpolation in degenerate case */
 		return normalize((1.0f - t)*q1 + t*q2);
 	}
 	else  {
+		/* slerp */
 		float theta = acosf(clamp(costheta, -1.0f, 1.0f));
 		float thetap = theta * t;
 		float4 qperp = normalize(q2 - q1 * costheta);