Fix for bug #1756

This was caused by a very primitive method of interpolating quaternions.
It was converting quats to mat and back to quat, and then just doing
a linear interpolation. That whilst quaternions are renowned for having
good interpolation possible.

I've experimented with 2 quaternion interpolation methods, and can only
get one to work correctly... the "official" version from Watt brothers
I can't get working, both are in arithb.c now.

Will arrange *close* review with experienced NLAers for it! But testing
here gives fully predictable results.

Also changed;
- added pointer check in drawaction
- changed puldown menu for correct hotkeys for move NLA strips up/down

5 files changed, 124 insertions, 20 deletions

diff --git a/source/blender/blenkernel/intern/action.c b/source/blender/blenkernel/intern/action.c
index 673c5080f2e..1740fe70247 100644
--- a/source/blender/blenkernel/intern/action.c
+++ b/source/blender/blenkernel/intern/action.c
@@ -178,26 +178,38 @@ void blend_poses(bPose *dst, const bPose *src, float srcweight, short mode)
 				 * This sucks because it is slow and stupid
 				 */
 				
-				QuatToMat3(dchan->quat, mat);
-				Mat3ToQuat(mat, dquat);
-				QuatToMat3(schan->quat, mat);
-				Mat3ToQuat(mat, squat);
+				//QuatToMat3(dchan->quat, mat);
+				//Mat3ToQuat(mat, dquat);
+				//QuatToMat3(schan->quat, mat);
+				//Mat3ToQuat(mat, squat);
 				
+				/* replaced quat->matrix->quat conversion with decent quaternion interpol (ton) */
 				/* Do the transformation blend */
+				if (schan->flag & POSE_ROT) {
+					QUATCOPY(dquat, dchan->quat);
+					QUATCOPY(squat, schan->quat);
+					if(mode==POSE_BLEND)
+						QuatInterpol(dchan->quat, dquat, squat, srcweight);
+					else
+						QuatAdd(dchan->quat, dquat, squat, srcweight);
+					NormalQuat (dchan->quat);
+				}
+
 				for (i=0; i<3; i++){
 					if (schan->flag & POSE_LOC)
 						dchan->loc[i] = (dchan->loc[i]*dstweight) + (schan->loc[i]*srcweight);
 					if (schan->flag & POSE_SIZE)
 						dchan->size[i] = 1.0f + ((dchan->size[i]-1.0f)*dstweight) + ((schan->size[i]-1.0f)*srcweight);
-					if (schan->flag & POSE_ROT)
-						dchan->quat[i+1] = (dquat[i+1]*dstweight) + (squat[i+1]*srcweight);
+					//if (schan->flag & POSE_ROT)
+					//	dchan->quat[i+1] = (dquat[i+1]*dstweight) + (squat[i+1]*srcweight);
 				}
 				
 				/* Do one more iteration for the quaternions only and normalize the quaternion if needed */
-				if (schan->flag & POSE_ROT)
-					dchan->quat[0] = 1.0f + ((dquat[0]-1.0f)*dstweight) + ((squat[0]-1.0f)*srcweight);
-				if (mode==POSE_BLEND)
-					NormalQuat (dchan->quat);
+				//if (schan->flag & POSE_ROT)
+				//	dchan->quat[0] = 1.0f + ((dquat[0]-1.0f)*dstweight) + ((squat[0]-1.0f)*srcweight);
+				//if (mode==POSE_BLEND)
+				//	NormalQuat (dchan->quat);
+				
 				dchan->flag |= schan->flag;
 			}
 		}
diff --git a/source/blender/blenlib/BLI_arithb.h b/source/blender/blenlib/BLI_arithb.h
index 9935932ca31..77081f99246 100644
--- a/source/blender/blenlib/BLI_arithb.h
+++ b/source/blender/blenlib/BLI_arithb.h
@@ -178,6 +178,11 @@ QuatSub(
 	float *q2
 );
 
+
+void QuatInterpol(float *result, float *quat1, float *quat2, float t);
+void QuatAdd(float *result, float *quat1, float *quat2, float t);
+
+
 /**
  * @section matrix multiplication can copying routines
  */
diff --git a/source/blender/blenlib/intern/arithb.c b/source/blender/blenlib/intern/arithb.c
index 08a26821ccd..caa4771ff4b 100644
--- a/source/blender/blenlib/intern/arithb.c
+++ b/source/blender/blenlib/intern/arithb.c
@@ -1386,6 +1386,92 @@ void VecUpMat3(float *vec, float mat[][3], short axis)
 	
 }
 
+/* A & M Watt, Advanced animation and rendering techniques, 1992 ACM press */
+
+void QuatInterpolW(float *result, float *quat1, float *quat2, float t)
+{
+	float omega, cosom, sinom, sc1, sc2;
+
+	cosom = quat1[0]*quat2[0] + quat1[1]*quat2[1] + quat1[2]*quat2[2] + quat1[3]*quat2[3] ;
+	
+	/* rotate around shortest angle */
+	if ((1.0 + cosom) > 0.0001) {
+		
+		if ((1.0 - cosom) > 0.0001) {
+			omega = acos(cosom);
+			sinom = sin(omega);
+			sc1 = sin((1.0 - t) * omega) / sinom;
+			sc2 = sin(t * omega) / sinom;
+		} 
+		else {
+			sc1 = 1.0 - t;
+			sc2 = t;
+		}
+		result[0] = sc1*quat1[0] + sc2*quat2[0];
+		result[1] = sc1*quat1[1] + sc2*quat2[1];
+		result[2] = sc1*quat1[2] + sc2*quat2[2];
+		result[3] = sc1*quat1[3] + sc2*quat2[3];
+	} 
+	else {
+		result[0] = quat2[3];
+		result[1] = -quat2[2];
+		result[2] = quat2[1];
+		result[3] = -quat2[0];
+		
+		sc1 = sin((1.0 - t)*M_PI_2);
+		sc2 = sin(t*M_PI_2);
+
+		result[0] = sc1*quat1[0] + sc2*result[0];
+		result[1] = sc1*quat1[1] + sc2*result[1];
+		result[2] = sc1*quat1[2] + sc2*result[2];
+		result[3] = sc1*quat1[3] + sc2*result[3];
+	}
+}
+
+void QuatInterpol(float *result, float *quat1, float *quat2, float t)
+{
+	float quat[4], omega, cosom, sinom, sc1, sc2;
+
+	cosom = quat1[0]*quat2[0] + quat1[1]*quat2[1] + quat1[2]*quat2[2] + quat1[3]*quat2[3] ;
+	
+	/* rotate around shortest angle */
+	if (cosom < 0.0) {
+		cosom = -cosom;
+		quat[0]= -quat1[0];
+		quat[1]= -quat1[1];
+		quat[2]= -quat1[2];
+		quat[3]= -quat1[3];
+	} 
+	else {
+		quat[0]= quat1[0];
+		quat[1]= quat1[1];
+		quat[2]= quat1[2];
+		quat[3]= quat1[3];
+	}
+	
+	if ((1.0 - cosom) > 0.0001) {
+		omega = acos(cosom);
+		sinom = sin(omega);
+		sc1 = sin((1 - t) * omega) / sinom;
+		sc2 = sin(t * omega) / sinom;
+	} else {
+		sc1= 1.0 - t;
+		sc2= t;
+	}
+	
+	result[0] = sc1 * quat[0] + sc2 * quat2[0];
+	result[1] = sc1 * quat[1] + sc2 * quat2[1];
+	result[2] = sc1 * quat[2] + sc2 * quat2[2];
+	result[3] = sc1 * quat[3] + sc2 * quat2[3];
+}
+
+void QuatAdd(float *result, float *quat1, float *quat2, float t)
+{
+	result[0]= quat1[0] + t*quat2[0];
+	result[1]= quat1[1] + t*quat2[1];
+	result[2]= quat1[2] + t*quat2[2];
+	result[3]= quat1[3] + t*quat2[3];
+}
 
 /* **************** VIEW / PROJECTION ********************************  */
 
diff --git a/source/blender/src/drawaction.c b/source/blender/src/drawaction.c
index 402f7684215..278be07b65b 100644
--- a/source/blender/src/drawaction.c
+++ b/source/blender/src/drawaction.c
@@ -877,15 +877,16 @@ static BezTriple **action_to_keylist(bAction *act, int flags, int *totvert)
 		/* Count required keys */
 		for (achan=act->chanbase.first; achan; achan=achan->next){
 			/* Count transformation keys */
-			for (icu=achan->ipo->curve.first; icu; icu=icu->next)
-				count+=icu->totvert;
-			
-			/* Count constraint keys */
-			for (conchan=achan->constraintChannels.first; conchan; conchan=conchan->next)
-				for (icu=conchan->ipo->curve.first; icu; icu=icu->next)
+			if(achan->ipo) {
+				for (icu=achan->ipo->curve.first; icu; icu=icu->next)
 					count+=icu->totvert;
-			
-
+				
+				/* Count constraint keys */
+				for (conchan=achan->constraintChannels.first; conchan; conchan=conchan->next)
+					for (icu=conchan->ipo->curve.first; icu; icu=icu->next)
+						count+=icu->totvert;
+				
+			}
 		}
 		
 		/* Build the list */
diff --git a/source/blender/src/header_nla.c b/source/blender/src/header_nla.c
index 332c0bece86..cdf2763eeab 100644
--- a/source/blender/src/header_nla.c
+++ b/source/blender/src/header_nla.c
@@ -289,8 +289,8 @@ static uiBlock *nla_stripmenu(void *arg_unused)
 	
 	uiDefBut(block, SEPR, 0, "",        0, yco-=6, menuwidth, 6, NULL, 0.0, 0.0, 0, 0, "");
 
-	uiDefIconTextBut(block, BUTM, 1, ICON_BLANK1, "Move Up|NumPad -", 0, yco-=20, menuwidth, 19, NULL, 0.0, 0.0, 0, 6, "");
-	uiDefIconTextBut(block, BUTM, 1, ICON_BLANK1, "Move Down|NumPad +", 0, yco-=20, menuwidth, 19, NULL, 0.0, 0.0, 0, 7, "");
+	uiDefIconTextBut(block, BUTM, 1, ICON_BLANK1, "Move Up|Page Down", 0, yco-=20, menuwidth, 19, NULL, 0.0, 0.0, 0, 6, "");
+	uiDefIconTextBut(block, BUTM, 1, ICON_BLANK1, "Move Down|Page Up", 0, yco-=20, menuwidth, 19, NULL, 0.0, 0.0, 0, 7, "");
 		
 	// uiDefIconTextBut(block, BUTM, 1, ICON_BLANK1, "Convert Action to NLA Strip|C", 0, yco-=20, menuwidth, 19, NULL, 0.0, 0.0, 0, 5, "");