Cycles: Fix wrong intersection with motion blur and degenerate object transform

11 files changed, 83 insertions, 57 deletions

diff --git a/intern/cycles/kernel/geom/geom_bvh_shadow.h b/intern/cycles/kernel/geom/geom_bvh_shadow.h
index e4cba99dc96..cb3f75f2a8f 100644
--- a/intern/cycles/kernel/geom/geom_bvh_shadow.h
+++ b/intern/cycles/kernel/geom/geom_bvh_shadow.h
@@ -59,7 +59,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 	float isect_t = tmax;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 #if BVH_FEATURE(BVH_INSTANCING)
@@ -302,7 +302,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 					object = kernel_tex_fetch(__prim_object, -primAddr-1);
 
 #if BVH_FEATURE(BVH_MOTION)
-					bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_tfm);
+					bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_itfm);
 #else
 					bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect_t);
 #endif
@@ -338,7 +338,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 				float t_fac;
 
 #if BVH_FEATURE(BVH_MOTION)
-				bvh_instance_motion_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac, &ob_tfm);
+				bvh_instance_motion_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac, &ob_itfm);
 #else
 				bvh_instance_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac);
 #endif
@@ -353,7 +353,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 				float ignore_t = FLT_MAX;
 
 #if BVH_FEATURE(BVH_MOTION)
-				bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &ignore_t, &ob_tfm);
+				bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &ignore_t, &ob_itfm);
 #else
 				bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &ignore_t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_bvh_subsurface.h b/intern/cycles/kernel/geom/geom_bvh_subsurface.h
index a73139f9c88..a093b9b55aa 100644
--- a/intern/cycles/kernel/geom/geom_bvh_subsurface.h
+++ b/intern/cycles/kernel/geom/geom_bvh_subsurface.h
@@ -63,7 +63,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 	uint num_hits = 0;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 #if defined(__KERNEL_SSE2__)
@@ -240,7 +240,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 						object = subsurface_object;
 
 #if BVH_FEATURE(BVH_MOTION)
-						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_tfm);
+						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_itfm);
 #else
 						bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect_t);
 #endif
@@ -278,7 +278,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 
 			/* instance pop */
 #if BVH_FEATURE(BVH_MOTION)
-			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_tfm);
+			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_itfm);
 #else
 			bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &isect_t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_bvh_traversal.h b/intern/cycles/kernel/geom/geom_bvh_traversal.h
index 73d79fd78ee..13d118b6d19 100644
--- a/intern/cycles/kernel/geom/geom_bvh_traversal.h
+++ b/intern/cycles/kernel/geom/geom_bvh_traversal.h
@@ -65,7 +65,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 	int object = OBJECT_NONE;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 	isect->t = ray->t;
@@ -342,7 +342,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 					object = kernel_tex_fetch(__prim_object, -primAddr-1);
 
 #if BVH_FEATURE(BVH_MOTION)
-					bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_tfm);
+					bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_itfm);
 #else
 					bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect->t);
 #endif
@@ -378,7 +378,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 
 			/* instance pop */
 #if BVH_FEATURE(BVH_MOTION)
-			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_tfm);
+			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_itfm);
 #else
 			bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &isect->t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_bvh_volume.h b/intern/cycles/kernel/geom/geom_bvh_volume.h
index 41c784869f2..656cd6e7a0e 100644
--- a/intern/cycles/kernel/geom/geom_bvh_volume.h
+++ b/intern/cycles/kernel/geom/geom_bvh_volume.h
@@ -59,7 +59,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 	const uint visibility = PATH_RAY_ALL_VISIBILITY;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 	isect->t = ray->t;
@@ -267,7 +267,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 					if(object_flag & SD_OBJECT_HAS_VOLUME) {
 
 #if BVH_FEATURE(BVH_MOTION)
-						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_tfm);
+						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_itfm);
 #else
 						bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect->t);
 #endif
@@ -307,7 +307,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 
 			/* instance pop */
 #if BVH_FEATURE(BVH_MOTION)
-			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_tfm);
+			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_itfm);
 #else
 			bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &isect->t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_bvh_volume_all.h b/intern/cycles/kernel/geom/geom_bvh_volume_all.h
index 5bb7a67f10b..8f7e3adae51 100644
--- a/intern/cycles/kernel/geom/geom_bvh_volume_all.h
+++ b/intern/cycles/kernel/geom/geom_bvh_volume_all.h
@@ -62,7 +62,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 	const uint visibility = PATH_RAY_ALL_VISIBILITY;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 #if BVH_FEATURE(BVH_INSTANCING)
@@ -230,7 +230,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 									if(num_hits == max_hits) {
 #if BVH_FEATURE(BVH_INSTANCING)
 #if BVH_FEATURE(BVH_MOTION)
-										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
+										float t_fac = 1.0f / len(transform_direction(&ob_itfm, dir));
 #else
 										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
 										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
@@ -268,7 +268,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 									if(num_hits == max_hits) {
 #if BVH_FEATURE(BVH_INSTANCING)
 #  if BVH_FEATURE(BVH_MOTION)
-										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
+										float t_fac = 1.0f / len(transform_direction(&ob_itfm, dir));
 #  else
 										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
 										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
@@ -311,7 +311,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 									if(num_hits == max_hits) {
 #if BVH_FEATURE(BVH_INSTANCING)
 #  if BVH_FEATURE(BVH_MOTION)
-										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
+										float t_fac = 1.0f / len(transform_direction(&ob_itfm, dir));
 #  else
 										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
 										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
@@ -341,7 +341,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 					if(object_flag & SD_OBJECT_HAS_VOLUME) {
 
 #if BVH_FEATURE(BVH_MOTION)
-						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_tfm);
+						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_itfm);
 #else
 						bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect_t);
 #endif
@@ -384,7 +384,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 			if(num_hits_in_instance) {
 				float t_fac;
 #if BVH_FEATURE(BVH_MOTION)
-				bvh_instance_motion_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac, &ob_tfm);
+				bvh_instance_motion_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac, &ob_itfm);
 #else
 				bvh_instance_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac);
 #endif
@@ -397,7 +397,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 			else {
 				float ignore_t = FLT_MAX;
 #if BVH_FEATURE(BVH_MOTION)
-				bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &ignore_t, &ob_tfm);
+				bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &ignore_t, &ob_itfm);
 #else
 				bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &ignore_t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_object.h b/intern/cycles/kernel/geom/geom_object.h
index bf1a3eb2413..ffd2f3b778f 100644
--- a/intern/cycles/kernel/geom/geom_object.h
+++ b/intern/cycles/kernel/geom/geom_object.h
@@ -453,15 +453,21 @@ ccl_device_inline void bvh_instance_pop_factor(KernelGlobals *kg, int object, co
 #ifdef __OBJECT_MOTION__
 /* Transform ray into object space to enter motion blurred object in BVH */
 
-ccl_device_inline void bvh_instance_motion_push(KernelGlobals *kg, int object, const Ray *ray, float3 *P, float3 *dir, float3 *idir, ccl_addr_space float *t, Transform *tfm)
+ccl_device_inline void bvh_instance_motion_push(KernelGlobals *kg,
+                                                int object,
+                                                const Ray *ray,
+                                                float3 *P,
+                                                float3 *dir,
+                                                float3 *idir,
+                                                ccl_addr_space float *t,
+                                                Transform *itfm)
 {
-	Transform itfm;
-	*tfm = object_fetch_transform_motion_test(kg, object, ray->time, &itfm);
+	object_fetch_transform_motion_test(kg, object, ray->time, itfm);
 
-	*P = transform_point(&itfm, ray->P);
+	*P = transform_point(itfm, ray->P);
 
 	float len;
-	*dir = bvh_clamp_direction(normalize_len(transform_direction(&itfm, ray->D), &len));
+	*dir = bvh_clamp_direction(normalize_len(transform_direction(itfm, ray->D), &len));
 	*idir = bvh_inverse_direction(*dir);
 
 	if(*t != FLT_MAX)
@@ -475,18 +481,24 @@ ccl_device_inline void bvh_instance_motion_push(KernelGlobals *kg, int object, c
  * TODO(sergey): Investigate if passing NULL instead of t1 gets optimized
  * so we can avoid having this duplication.
  */
-ccl_device_inline void qbvh_instance_motion_push(KernelGlobals *kg, int object, const Ray *ray, float3 *P, float3 *dir, float3 *idir, float *t, float *t1, Transform *tfm)
+ccl_device_inline void qbvh_instance_motion_push(KernelGlobals *kg,
+                                                 int object,
+                                                 const Ray *ray,
+                                                 float3 *P,
+                                                 float3 *dir,
+                                                 float3 *idir,
+                                                 float *t,
+                                                 float *t1,
+                                                 Transform *itfm)
 {
-	Transform itfm;
-	*tfm = object_fetch_transform_motion_test(kg, object, ray->time, &itfm);
+	object_fetch_transform_motion_test(kg, object, ray->time, itfm);
 
-	*P = transform_point(&itfm, ray->P);
+	*P = transform_point(itfm, ray->P);
 
 	float len;
-	*dir = bvh_clamp_direction(normalize_len(transform_direction(&itfm, ray->D), &len));
+	*dir = bvh_clamp_direction(normalize_len(transform_direction(itfm, ray->D), &len));
 	*idir = bvh_inverse_direction(*dir);
 
-
 	if(*t != FLT_MAX)
 		*t *= len;
 
@@ -497,10 +509,18 @@ ccl_device_inline void qbvh_instance_motion_push(KernelGlobals *kg, int object,
 
 /* Transorm ray to exit motion blurred object in BVH */
 
-ccl_device_inline void bvh_instance_motion_pop(KernelGlobals *kg, int object, const Ray *ray, float3 *P, float3 *dir, float3 *idir, ccl_addr_space float *t, Transform *tfm)
+ccl_device_inline void bvh_instance_motion_pop(KernelGlobals *kg,
+                                               int object,
+                                               const Ray *ray,
+                                               float3 *P,
+                                               float3 *dir,
+                                               float3 *idir,
+                                               ccl_addr_space float *t,
+                                               Transform *itfm)
 {
-	if(*t != FLT_MAX)
-		*t *= len(transform_direction(tfm, 1.0f/(*idir)));
+	if(*t != FLT_MAX) {
+		*t /= len(transform_direction(itfm, ray->D));
+	}
 
 	*P = ray->P;
 	*dir = bvh_clamp_direction(ray->D);
@@ -509,10 +529,16 @@ ccl_device_inline void bvh_instance_motion_pop(KernelGlobals *kg, int object, co
 
 /* Same as above, but returns scale factor to apply to multiple intersection distances */
 
-ccl_device_inline void bvh_instance_motion_pop_factor(KernelGlobals *kg, int object, const Ray *ray, float3 *P, float3 *dir, float3 *idir, float *t_fac, Transform *tfm)
+ccl_device_inline void bvh_instance_motion_pop_factor(KernelGlobals *kg,
+                                                      int object,
+                                                      const Ray *ray,
+                                                      float3 *P,
+                                                      float3 *dir,
+                                                      float3 *idir,
+                                                      float *t_fac,
+                                                      Transform *itfm)
 {
-	*t_fac = len(transform_direction(tfm, 1.0f/(*idir)));
-
+	*t_fac /= len(transform_direction(itfm, ray->D));
 	*P = ray->P;
 	*dir = bvh_clamp_direction(ray->D);
 	*idir = bvh_inverse_direction(*dir);
diff --git a/intern/cycles/kernel/geom/geom_qbvh_shadow.h b/intern/cycles/kernel/geom/geom_qbvh_shadow.h
index dc37e6ecfa4..4564d5baf5e 100644
--- a/intern/cycles/kernel/geom/geom_qbvh_shadow.h
+++ b/intern/cycles/kernel/geom/geom_qbvh_shadow.h
@@ -55,7 +55,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 	float isect_t = tmax;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 	*num_hits = 0;
@@ -317,7 +317,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 					object = kernel_tex_fetch(__prim_object, -primAddr-1);
 
 #if BVH_FEATURE(BVH_MOTION)
-					bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_tfm);
+					bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_itfm);
 #else
 					bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect_t);
 #endif
@@ -357,7 +357,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 				float t_fac;
 
 #if BVH_FEATURE(BVH_MOTION)
-				bvh_instance_motion_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac, &ob_tfm);
+				bvh_instance_motion_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac, &ob_itfm);
 #else
 				bvh_instance_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac);
 #endif
@@ -370,7 +370,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 				float ignore_t = FLT_MAX;
 
 #if BVH_FEATURE(BVH_MOTION)
-				bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &ignore_t, &ob_tfm);
+				bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &ignore_t, &ob_itfm);
 #else
 				bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &ignore_t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_qbvh_subsurface.h b/intern/cycles/kernel/geom/geom_qbvh_subsurface.h
index d85e1a4691e..fe231720cf7 100644
--- a/intern/cycles/kernel/geom/geom_qbvh_subsurface.h
+++ b/intern/cycles/kernel/geom/geom_qbvh_subsurface.h
@@ -58,7 +58,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 	uint num_hits = 0;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 #ifndef __KERNEL_SSE41__
@@ -256,7 +256,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 						object = subsurface_object;
 
 #if BVH_FEATURE(BVH_MOTION)
-						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_tfm);
+						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_itfm);
 #else
 						bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect_t);
 #endif
@@ -297,7 +297,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 
 			/* Instance pop. */
 #if BVH_FEATURE(BVH_MOTION)
-			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_tfm);
+			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_itfm);
 #else
 			bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &isect_t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_qbvh_traversal.h b/intern/cycles/kernel/geom/geom_qbvh_traversal.h
index 7e356ea062b..4e1678665c0 100644
--- a/intern/cycles/kernel/geom/geom_qbvh_traversal.h
+++ b/intern/cycles/kernel/geom/geom_qbvh_traversal.h
@@ -63,7 +63,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 	int object = OBJECT_NONE;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 #ifndef __KERNEL_SSE41__
@@ -356,7 +356,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 					object = kernel_tex_fetch(__prim_object, -primAddr-1);
 
 #if BVH_FEATURE(BVH_MOTION)
-					qbvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect->t, &nodeDist, &ob_tfm);
+					qbvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect->t, &nodeDist, &ob_itfm);
 #else
 					qbvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect->t, &nodeDist);
 #endif
@@ -395,7 +395,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 
 			/* Instance pop. */
 #if BVH_FEATURE(BVH_MOTION)
-			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_tfm);
+			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_itfm);
 #else
 			bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &isect->t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_qbvh_volume.h b/intern/cycles/kernel/geom/geom_qbvh_volume.h
index d8cfa3a4061..40864471d13 100644
--- a/intern/cycles/kernel/geom/geom_qbvh_volume.h
+++ b/intern/cycles/kernel/geom/geom_qbvh_volume.h
@@ -54,7 +54,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 	const uint visibility = PATH_RAY_ALL_VISIBILITY;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 #ifndef __KERNEL_SSE41__
@@ -281,7 +281,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 					if(object_flag & SD_OBJECT_HAS_VOLUME) {
 
 #if BVH_FEATURE(BVH_MOTION)
-						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_tfm);
+						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_itfm);
 #else
 						bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect->t);
 #endif
@@ -322,7 +322,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 
 			/* Instance pop. */
 #if BVH_FEATURE(BVH_MOTION)
-			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_tfm);
+			bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &isect->t, &ob_itfm);
 #else
 			bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &isect->t);
 #endif
diff --git a/intern/cycles/kernel/geom/geom_qbvh_volume_all.h b/intern/cycles/kernel/geom/geom_qbvh_volume_all.h
index 2baf23d6bd6..75e4c4e8d96 100644
--- a/intern/cycles/kernel/geom/geom_qbvh_volume_all.h
+++ b/intern/cycles/kernel/geom/geom_qbvh_volume_all.h
@@ -57,7 +57,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 	const uint visibility = PATH_RAY_ALL_VISIBILITY;
 
 #if BVH_FEATURE(BVH_MOTION)
-	Transform ob_tfm;
+	Transform ob_itfm;
 #endif
 
 	uint num_hits = 0;
@@ -247,7 +247,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 									if(num_hits == max_hits) {
 #if BVH_FEATURE(BVH_INSTANCING)
 #if BVH_FEATURE(BVH_MOTION)
-										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
+										float t_fac = 1.0f / len(transform_direction(&ob_itfm, dir));
 #else
 										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
 										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
@@ -285,7 +285,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 									if(num_hits == max_hits) {
 #if BVH_FEATURE(BVH_INSTANCING)
 #  if BVH_FEATURE(BVH_MOTION)
-										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
+										float t_fac = 1.0f / len(transform_direction(&ob_itfm, dir));
 #  else
 										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
 										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
@@ -328,7 +328,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 									if(num_hits == max_hits) {
 #if BVH_FEATURE(BVH_INSTANCING)
 #  if BVH_FEATURE(BVH_MOTION)
-										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
+										float t_fac = 1.0f / len(transform_direction(&ob_itfm, dir));
 #  else
 										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
 										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
@@ -355,7 +355,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 					if(object_flag & SD_OBJECT_HAS_VOLUME) {
 
 #if BVH_FEATURE(BVH_MOTION)
-						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_tfm);
+						bvh_instance_motion_push(kg, object, ray, &P, &dir, &idir, &isect_t, &ob_itfm);
 #else
 						bvh_instance_push(kg, object, ray, &P, &dir, &idir, &isect_t);
 #endif
@@ -400,7 +400,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 			if(num_hits_in_instance) {
 				float t_fac;
 #if BVH_FEATURE(BVH_MOTION)
-				bvh_instance_motion_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac, &ob_tfm);
+				bvh_instance_motion_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac, &ob_itfm);
 #else
 				bvh_instance_pop_factor(kg, object, ray, &P, &dir, &idir, &t_fac);
 #endif
@@ -413,7 +413,7 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 			else {
 				float ignore_t = FLT_MAX;
 #if BVH_FEATURE(BVH_MOTION)
-				bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &ignore_t, &ob_tfm);
+				bvh_instance_motion_pop(kg, object, ray, &P, &dir, &idir, &ignore_t, &ob_itfm);
 #else
 				bvh_instance_pop(kg, object, ray, &P, &dir, &idir, &ignore_t);
 #endif