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, 38 insertions, 25 deletions

diff --git a/intern/cycles/kernel/geom/geom_qbvh_volume.h b/intern/cycles/kernel/geom/geom_qbvh_volume.h
index 9e6e7552b3f..8d4523c3486 100644
--- a/intern/cycles/kernel/geom/geom_qbvh_volume.h
+++ b/intern/cycles/kernel/geom/geom_qbvh_volume.h
@@ -209,49 +209,62 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 				if(primAddr >= 0) {
 #endif
 					int primAddr2 = __float_as_int(leaf.y);
+					const uint type = __float_as_int(leaf.w);
+					const uint p_type = type & PRIMITIVE_ALL;
 
 					/* Pop. */
 					nodeAddr = traversalStack[stackPtr].addr;
 					--stackPtr;
 
 					/* Primitive intersection. */
-					for(; primAddr < primAddr2; primAddr++) {
-						/* Only primitives from volume object. */
-						uint tri_object = (object == OBJECT_NONE)? kernel_tex_fetch(__prim_object, primAddr): object;
-						int object_flag = kernel_tex_fetch(__object_flag, tri_object);
-
-						if((object_flag & SD_OBJECT_HAS_VOLUME) == 0) {
-							continue;
-						}
-
-						/* Intersect ray against primitive. */
-						uint type = kernel_tex_fetch(__prim_type, primAddr);
-
-						switch(type & PRIMITIVE_ALL) {
-							case PRIMITIVE_TRIANGLE: {
+					switch(p_type) {
+						case PRIMITIVE_TRIANGLE: {
+							for(; primAddr < primAddr2; primAddr++) {
+								/* Only primitives from volume object. */
+								uint tri_object = (object == OBJECT_NONE)? kernel_tex_fetch(__prim_object, primAddr): object;
+								int object_flag = kernel_tex_fetch(__object_flag, tri_object);
+								if((object_flag & SD_OBJECT_HAS_VOLUME) == 0) {
+									continue;
+								}
+								/* Intersect ray against primitive. */
 								triangle_intersect(kg, &isect_precalc, isect, P, dir, visibility, object, primAddr);
-								break;
 							}
+							break;
+						}
 #if BVH_FEATURE(BVH_MOTION)
-							case PRIMITIVE_MOTION_TRIANGLE: {
+						case PRIMITIVE_MOTION_TRIANGLE: {
+							for(; primAddr < primAddr2; primAddr++) {
+								/* Only primitives from volume object. */
+								uint tri_object = (object == OBJECT_NONE)? kernel_tex_fetch(__prim_object, primAddr): object;
+								int object_flag = kernel_tex_fetch(__object_flag, tri_object);
+								if((object_flag & SD_OBJECT_HAS_VOLUME) == 0) {
+									continue;
+								}
+								/* Intersect ray against primitive. */
 								motion_triangle_intersect(kg, isect, P, dir, ray->time, visibility, object, primAddr);
-								break;
 							}
+							break;
+						}
 #endif
 #if BVH_FEATURE(BVH_HAIR)
-							case PRIMITIVE_CURVE:
-							case PRIMITIVE_MOTION_CURVE: {
-								if(kernel_data.curve.curveflags & CURVE_KN_INTERPOLATE) 
+						case PRIMITIVE_CURVE:
+						case PRIMITIVE_MOTION_CURVE: {
+							for(; primAddr < primAddr2; primAddr++) {
+								/* Only primitives from volume object. */
+								uint tri_object = (object == OBJECT_NONE)? kernel_tex_fetch(__prim_object, primAddr): object;
+								int object_flag = kernel_tex_fetch(__object_flag, tri_object);
+								if((object_flag & SD_OBJECT_HAS_VOLUME) == 0) {
+									continue;
+								}
+								/* Intersect ray against primitive. */
+								if(kernel_data.curve.curveflags & CURVE_KN_INTERPOLATE)
 									bvh_cardinal_curve_intersect(kg, isect, P, dir, visibility, object, primAddr, ray->time, type, NULL, 0, 0);
 								else
 									bvh_curve_intersect(kg, isect, P, dir, visibility, object, primAddr, ray->time, type, NULL, 0, 0);
-								break;
-							}
-#endif
-							default: {
-								break;
 							}
+							break;
 						}
+#endif
 					}
 				}
 #if BVH_FEATURE(BVH_INSTANCING)