Cycles: Add debug pass which shows number of instance pushes during camera ray intersection

TODO: We might want to refactor debug passes into PASS_DEBUG and some
debug_type (similar to Blender's side passes) to avoid issue of running
out of bits.

intern/cycles/blender/blender_session.cpp

@@ -271,6 +271,8 @@ static PassType get_pass_type(BL::RenderPass b_pass)
 		{
 			if(b_pass.debug_type() == BL::RenderPass::debug_type_BVH_TRAVERSAL_STEPS)
 				return PASS_BVH_TRAVERSAL_STEPS;
+			if(b_pass.debug_type() == BL::RenderPass::debug_type_BVH_TRAVERSED_INSTANCES)
+				return PASS_BVH_TRAVERSED_INSTANCES;
 			if(b_pass.debug_type() == BL::RenderPass::debug_type_RAY_BOUNCES)
 				return PASS_RAY_BOUNCES;
 			break;

intern/cycles/kernel/geom/geom_bvh_traversal.h

@@ -76,6 +76,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 
 #if defined(__KERNEL_DEBUG__)
 	isect->num_traversal_steps = 0;
+	isect->num_traversed_instances = 0;
 #endif
 
 #if defined(__KERNEL_SSE2__)
@@ -362,6 +363,10 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(BVH)(KernelGlobals *kg,
 					traversalStack[stackPtr] = ENTRYPOINT_SENTINEL;
 
 					nodeAddr = kernel_tex_fetch(__object_node, object);
+
+#if defined(__KERNEL_DEBUG__)
+					isect->num_traversed_instances++;
+#endif
 				}
 			}
 #endif  /* FEATURE(BVH_INSTANCING) */

intern/cycles/kernel/geom/geom_qbvh_traversal.h

@@ -80,6 +80,7 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 
 #if defined(__KERNEL_DEBUG__)
 	isect->num_traversal_steps = 0;
+	isect->num_traversed_instances = 0;
 #endif
 
 	ssef tnear(0.0f), tfar(ray->t);
@@ -377,6 +378,10 @@ ccl_device bool BVH_FUNCTION_FULL_NAME(QBVH)(KernelGlobals *kg,
 					traversalStack[stackPtr].dist = -FLT_MAX;
 
 					nodeAddr = kernel_tex_fetch(__object_node, object);
+
+#if defined(__KERNEL_DEBUG__)
+					isect->num_traversed_instances++;
+#endif
 				}
 			}
 #endif  /* FEATURE(BVH_INSTANCING) */

intern/cycles/kernel/kernel_debug.h

@@ -19,6 +19,7 @@ CCL_NAMESPACE_BEGIN
 ccl_device_inline void debug_data_init(DebugData *debug_data)
 {
 	debug_data->num_bvh_traversal_steps = 0;
+	debug_data->num_bvh_traversed_instances = 0;
 	debug_data->num_ray_bounces = 0;
 }
 
@@ -34,6 +35,11 @@ ccl_device_inline void kernel_write_debug_passes(KernelGlobals *kg,
 		                        sample,
 		                        debug_data->num_bvh_traversal_steps);
 	}
+	if(flag & PASS_BVH_TRAVERSED_INSTANCES) {
+		kernel_write_pass_float(buffer + kernel_data.film.pass_bvh_traversed_instances,
+		                        sample,
+		                        debug_data->num_bvh_traversed_instances);
+	}
 	if(flag & PASS_RAY_BOUNCES) {
 		kernel_write_pass_float(buffer + kernel_data.film.pass_ray_bounces,
 		                        sample,

intern/cycles/kernel/kernel_path.h

@@ -476,6 +476,7 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
 #ifdef __KERNEL_DEBUG__
 		if(state.flag & PATH_RAY_CAMERA) {
 			debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
+			debug_data.num_bvh_traversed_instances += isect.num_traversed_instances;
 		}
 		debug_data.num_ray_bounces++;
 #endif
@@ -878,6 +879,7 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
 #ifdef __KERNEL_DEBUG__
 		if(state.flag & PATH_RAY_CAMERA) {
 			debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
+			debug_data.num_bvh_traversed_instances += isect.num_traversed_instances;
 		}
 		debug_data.num_ray_bounces++;
 #endif

intern/cycles/kernel/kernel_types.h

@@ -339,7 +339,8 @@ typedef enum PassType {
 	PASS_LIGHT = (1 << 25), /* no real pass, used to force use_light_pass */
 #ifdef __KERNEL_DEBUG__
 	PASS_BVH_TRAVERSAL_STEPS = (1 << 26),
-	PASS_RAY_BOUNCES = (1 << 27),
+	PASS_BVH_TRAVERSED_INSTANCES = (1 << 27),
+	PASS_RAY_BOUNCES = (1 << 28),
 #endif
 } PassType;
 
@@ -501,6 +502,7 @@ typedef ccl_addr_space struct Intersection {
 
 #ifdef __KERNEL_DEBUG__
 	int num_traversal_steps;
+	int num_traversed_instances;
 #endif
 } Intersection;
 
@@ -851,8 +853,9 @@ typedef struct KernelFilm {
 
 #ifdef __KERNEL_DEBUG__
 	int pass_bvh_traversal_steps;
+	int pass_bvh_traversed_instances;
 	int pass_ray_bounces;
-	int pass_pad3, pass_pad4;
+	int pass_pad3;
 #endif
 } KernelFilm;
 
@@ -991,6 +994,7 @@ typedef ccl_addr_space struct DebugData {
 	// Total number of BVH node traversal steps and primitives intersections
 	// for the camera rays.
 	int num_bvh_traversal_steps;
+	int num_bvh_traversed_instances;
 	int num_ray_bounces;
 } DebugData;
 #endif

intern/cycles/kernel/split/kernel_scene_intersect.h

@@ -123,6 +123,7 @@ ccl_device void kernel_scene_intersect(
 #ifdef __KERNEL_DEBUG__
 	if(state.flag & PATH_RAY_CAMERA) {
 		debug_data->num_bvh_traversal_steps += isect->num_traversal_steps;
+		debug_data->num_bvh_traversed_instances += isect->num_traversed_instances;
 	}
 	debug_data->num_ray_bounces++;
 #endif

intern/cycles/render/film.cpp

@@ -151,6 +151,10 @@ void Pass::add(PassType type, vector<Pass>& passes)
 			pass.components = 1;
 			pass.exposure = false;
 			break;
+		case PASS_BVH_TRAVERSED_INSTANCES:
+			pass.components = 1;
+			pass.exposure = false;
+			break;
 		case PASS_RAY_BOUNCES:
 			pass.components = 1;
 			pass.exposure = false;
@@ -403,6 +407,9 @@ void Film::device_update(Device *device, DeviceScene *dscene, Scene *scene)
 			case PASS_BVH_TRAVERSAL_STEPS:
 				kfilm->pass_bvh_traversal_steps = kfilm->pass_stride;
 				break;
+			case PASS_BVH_TRAVERSED_INSTANCES:
+				kfilm->pass_bvh_traversed_instances = kfilm->pass_stride;
+				break;
 			case PASS_RAY_BOUNCES:
 				kfilm->pass_ray_bounces = kfilm->pass_stride;
 				break;

source/blender/makesrna/intern/rna_render.c

@@ -79,6 +79,7 @@ EnumPropertyItem render_pass_type_items[] = {
 
 EnumPropertyItem render_pass_debug_type_items[] = {
 	{RENDER_PASS_DEBUG_BVH_TRAVERSAL_STEPS, "BVH_TRAVERSAL_STEPS", 0, "BVH Traversal Steps", ""},
+	{RENDER_PASS_DEBUG_BVH_TRAVERSED_INSTANCES, "BVH_TRAVERSED_INSTANCES", 0, "BVH Traversed Instances", ""},
 	{RENDER_PASS_DEBUG_RAY_BOUNCES, "RAY_BOUNCES", 0, "Ray Steps", ""},
 	{0, NULL, 0, NULL, NULL}
 };

source/blender/render/extern/include/RE_pipeline.h

@@ -99,7 +99,8 @@ typedef struct RenderPass {
 
 enum {
 	RENDER_PASS_DEBUG_BVH_TRAVERSAL_STEPS = 0,
-	RENDER_PASS_DEBUG_RAY_BOUNCES = 1,
+	RENDER_PASS_DEBUG_BVH_TRAVERSED_INSTANCES = 1,
+	RENDER_PASS_DEBUG_RAY_BOUNCES = 2,
 };
 
 /* a renderlayer is a full image, but with all passes and samples */

source/blender/render/intern/source/render_result.c

@@ -531,6 +531,8 @@ static const char *debug_pass_type_name_get(int debug_type)
 	switch (debug_type) {
 		case RENDER_PASS_DEBUG_BVH_TRAVERSAL_STEPS:
 			return "BVH Traversal Steps";
+		case RENDER_PASS_DEBUG_BVH_TRAVERSED_INSTANCES:
+			return "BVH Traversed Instances";
 		case RENDER_PASS_DEBUG_RAY_BOUNCES:
 			return "Ray Bounces";
 	}