[Bf-blender-cvs] [8fa4fcc] master: Cycles: Fix intersection issues caused by degenerate instance matrix

[Sergey Sharybin]

Commit: 8fa4fccec42ac98cfbc2652c8016d80c336564c4
Author: Sergey Sharybin
Date:   Thu Oct 8 20:30:51 2015 +0500
Branches: master
https://developer.blender.org/rB8fa4fccec42ac98cfbc2652c8016d80c336564c4

Cycles: Fix intersection issues caused by degenerate instance matrix

Issue was caused by wrong intersection distance scaling on instance pop,
which could cause intersection distance to become zero, confusing following
intersection checks.

===================================================================

M	intern/cycles/kernel/geom/geom_bvh_volume_all.h
M	intern/cycles/kernel/geom/geom_object.h
M	intern/cycles/kernel/geom/geom_qbvh_volume_all.h

===================================================================

diff --git a/intern/cycles/kernel/geom/geom_bvh_volume_all.h b/intern/cycles/kernel/geom/geom_bvh_volume_all.h
index b6db36f..5bb7a67 100644
--- a/intern/cycles/kernel/geom/geom_bvh_volume_all.h
+++ b/intern/cycles/kernel/geom/geom_bvh_volume_all.h
@@ -232,8 +232,8 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 #if BVH_FEATURE(BVH_MOTION)
 										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
 #else
-										Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
-										float t_fac = len(transform_direction(&tfm, 1.0f/idir));
+										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
+										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
 #endif
 										for(int i = 0; i < num_hits_in_instance; i++) {
 											(isect_array-i-1)->t *= t_fac;
@@ -270,8 +270,8 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 #  if BVH_FEATURE(BVH_MOTION)
 										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
 #  else
-										Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
-										float t_fac = len(transform_direction(&tfm, 1.0f/idir));
+										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
+										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
 #endif
 										for(int i = 0; i < num_hits_in_instance; i++) {
 											(isect_array-i-1)->t *= t_fac;
@@ -313,8 +313,8 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 #  if BVH_FEATURE(BVH_MOTION)
 										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
 #  else
-										Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
-										float t_fac = len(transform_direction(&tfm, 1.0f/idir));
+										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
+										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
 #endif
 										for(int i = 0; i < num_hits_in_instance; i++) {
 											(isect_array-i-1)->t *= t_fac;
diff --git a/intern/cycles/kernel/geom/geom_object.h b/intern/cycles/kernel/geom/geom_object.h
index 9d0a008..bf1a3eb 100644
--- a/intern/cycles/kernel/geom/geom_object.h
+++ b/intern/cycles/kernel/geom/geom_object.h
@@ -428,8 +428,8 @@ ccl_device_inline void qbvh_instance_push(KernelGlobals *kg,
 ccl_device_inline void bvh_instance_pop(KernelGlobals *kg, int object, const Ray *ray, float3 *P, float3 *dir, float3 *idir, ccl_addr_space float *t)
 {
 	if(*t != FLT_MAX) {
-		Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
-		*t *= len(transform_direction(&tfm, 1.0f/(*idir)));
+		Transform tfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
+		*t /= len(transform_direction(&tfm, ray->D));
 	}
 
 	*P = ray->P;
@@ -441,8 +441,8 @@ ccl_device_inline void bvh_instance_pop(KernelGlobals *kg, int object, const Ray
 
 ccl_device_inline void bvh_instance_pop_factor(KernelGlobals *kg, int object, const Ray *ray, float3 *P, float3 *dir, float3 *idir, float *t_fac)
 {
-	Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
-	*t_fac = len(transform_direction(&tfm, 1.0f/(*idir)));
+	Transform tfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
+	*t_fac = 1.0f / len(transform_direction(&tfm, ray->D));
 
 	*P = ray->P;
 	*dir = bvh_clamp_direction(ray->D);
diff --git a/intern/cycles/kernel/geom/geom_qbvh_volume_all.h b/intern/cycles/kernel/geom/geom_qbvh_volume_all.h
index 056ca9a..2baf23d 100644
--- a/intern/cycles/kernel/geom/geom_qbvh_volume_all.h
+++ b/intern/cycles/kernel/geom/geom_qbvh_volume_all.h
@@ -249,8 +249,8 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 #if BVH_FEATURE(BVH_MOTION)
 										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
 #else
-										Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
-										float t_fac = len(transform_direction(&tfm, 1.0f/idir));
+										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
+										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
 #endif
 										for(int i = 0; i < num_hits_in_instance; i++) {
 											(isect_array-i-1)->t *= t_fac;
@@ -287,8 +287,8 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 #  if BVH_FEATURE(BVH_MOTION)
 										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
 #  else
-										Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
-										float t_fac = len(transform_direction(&tfm, 1.0f/idir));
+										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
+										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
 #endif
 										for(int i = 0; i < num_hits_in_instance; i++) {
 											(isect_array-i-1)->t *= t_fac;
@@ -330,8 +330,8 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 #  if BVH_FEATURE(BVH_MOTION)
 										float t_fac = len(transform_direction(&ob_tfm, 1.0f/idir));
 #  else
-										Transform tfm = object_fetch_transform(kg, object, OBJECT_TRANSFORM);
-										float t_fac = len(transform_direction(&tfm, 1.0f/idir));
+										Transform itfm = object_fetch_transform(kg, object, OBJECT_INVERSE_TRANSFORM);
+										float t_fac = 1.0f / len(transform_direction(&itfm, dir));
 #endif
 										for(int i = 0; i < num_hits_in_instance; i++) {
 											(isect_array-i-1)->t *= t_fac;