Cycles: Enable leaf split by primitive type and adopt BVH traversal for this

This commit enables BVH leaf nodes split by the primitive type and makes it
so BVH traversal code is now aware and benefits from this.

As was mentioned in original commit, this change is crucial to be able to do
single ray to multiple triangle intersection. But it also appears to give
barely visible speedup in some scene.

In any case there should be no noticeable slowdown, and this change is what
we need to have anyway.

1 files changed, 23 insertions, 19 deletions

diff --git a/intern/cycles/kernel/geom/geom_bvh_subsurface.h b/intern/cycles/kernel/geom/geom_bvh_subsurface.h
index ea9d7c07a72..2f078d51985 100644
--- a/intern/cycles/kernel/geom/geom_bvh_subsurface.h
+++ b/intern/cycles/kernel/geom/geom_bvh_subsurface.h
@@ -193,37 +193,41 @@ ccl_device uint BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 #if BVH_FEATURE(BVH_INSTANCING)
 				if(primAddr >= 0) {
 #endif
-					int primAddr2 = __float_as_int(leaf.y);
+					const int primAddr2 = __float_as_int(leaf.y);
+					const uint type = __float_as_int(leaf.w);
 
 					/* pop */
 					nodeAddr = traversalStack[stackPtr];
 					--stackPtr;
 
 					/* primitive intersection */
-					for(; primAddr < primAddr2; primAddr++) {
-						/* only primitives from the same object */
-						uint tri_object = (object == OBJECT_NONE)? kernel_tex_fetch(__prim_object, primAddr): object;
-
-						if(tri_object != subsurface_object)
-							continue;
-
-						/* intersect ray against primitive */
-						uint type = kernel_tex_fetch(__prim_type, primAddr);
-
-						switch(type & PRIMITIVE_ALL) {
-							case PRIMITIVE_TRIANGLE: {
+					switch(type & PRIMITIVE_ALL) {
+						case PRIMITIVE_TRIANGLE: {
+							/* intersect ray against primitive */
+							for(; primAddr < primAddr2; primAddr++) {
+								/* only primitives from the same object */
+								uint tri_object = (object == OBJECT_NONE)? kernel_tex_fetch(__prim_object, primAddr): object;
+								if(tri_object != subsurface_object)
+									continue;
 								triangle_intersect_subsurface(kg, &isect_precalc, isect_array, P, dir, object, primAddr, isect_t, &num_hits, lcg_state, max_hits);
-								break;
 							}
+							break;
+						}
 #if BVH_FEATURE(BVH_MOTION)
-							case PRIMITIVE_MOTION_TRIANGLE: {
+						case PRIMITIVE_MOTION_TRIANGLE: {
+							/* intersect ray against primitive */
+							for(; primAddr < primAddr2; primAddr++) {
+								/* only primitives from the same object */
+								uint tri_object = (object == OBJECT_NONE)? kernel_tex_fetch(__prim_object, primAddr): object;
+								if(tri_object != subsurface_object)
+									continue;
 								motion_triangle_intersect_subsurface(kg, isect_array, P, dir, ray->time, object, primAddr, isect_t, &num_hits, lcg_state, max_hits);
-								break;
 							}
+							break;
+						}
 #endif
-							default: {
-								break;
-							}
+						default: {
+							break;
 						}
 					}
 				}