Fix for bug #7368: flipping issue with dual quaternions and scaled bones.

1 files changed, 9 insertions, 2 deletions

diff --git a/source/blender/blenlib/intern/arithb.c b/source/blender/blenlib/intern/arithb.c
index 3514e695f59..d4a1b3a8bfc 100644
--- a/source/blender/blenlib/intern/arithb.c
+++ b/source/blender/blenlib/intern/arithb.c
@@ -1727,9 +1727,13 @@ void DQuatToMat4(DualQuat *dq, float mat[][4])
 
 void DQuatAddWeighted(DualQuat *dqsum, DualQuat *dq, float weight)
 {
+	int flipped= 0;
+
 	/* make sure we interpolate quats in the right direction */
-	if (QuatDot(dq->quat, dqsum->quat) < 0)
-		weight = -weight;
+	if (QuatDot(dq->quat, dqsum->quat) < 0) {
+		flipped= 1;
+		weight= -weight;
+	}
 
 	/* interpolate rotation and translation */
 	dqsum->quat[0] += weight*dq->quat[0];
@@ -1746,6 +1750,9 @@ void DQuatAddWeighted(DualQuat *dqsum, DualQuat *dq, float weight)
 	if (dq->scale_weight) {
 		float wmat[4][4];
 
+		if(flipped)	/* we don't want negative weights for scaling */
+			weight= -weight;
+
 		Mat4CpyMat4(wmat, dq->scale);
 		Mat4MulFloat((float*)wmat, weight);
 		Mat4AddMat4(dqsum->scale, dqsum->scale, wmat);