Cycles: Add debug pass showing average number of ray bounces per pixel

Quite straightforward implementation, but still needs some work for the split
kernel. Includes both regular and split kernel implementation for that.

The pass is not exposed to the interface yet because it's currently not really
easy to have same pass listed in the menu multiple times.

4 files changed, 13 insertions, 1 deletions

diff --git a/intern/cycles/kernel/kernel_debug.h b/intern/cycles/kernel/kernel_debug.h
index 94ede397848..da9a48a11f9 100644
--- a/intern/cycles/kernel/kernel_debug.h
+++ b/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_ray_bounces = 0;
 }
 
 ccl_device_inline void kernel_write_debug_passes(KernelGlobals *kg,
@@ -33,6 +34,11 @@ ccl_device_inline void kernel_write_debug_passes(KernelGlobals *kg,
 		                        sample,
 		                        debug_data->num_bvh_traversal_steps);
 	}
+	if(flag & PASS_RAY_BOUNCES) {
+		kernel_write_pass_float(buffer + kernel_data.film.pass_ray_bounces,
+		                        sample,
+		                        debug_data->num_ray_bounces);
+	}
 }
 
 CCL_NAMESPACE_END
diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index e2dbf6e22f7..857d97329b6 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -477,6 +477,7 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
 		if(state.flag & PATH_RAY_CAMERA) {
 			debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
 		}
+		debug_data.num_ray_bounces++;
 #endif
 
 #ifdef __LAMP_MIS__
@@ -878,6 +879,7 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
 		if(state.flag & PATH_RAY_CAMERA) {
 			debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
 		}
+		debug_data.num_ray_bounces++;
 #endif
 
 #ifdef __VOLUME__
diff --git a/intern/cycles/kernel/kernel_types.h b/intern/cycles/kernel/kernel_types.h
index 1ef07629a3e..67e41a5ee81 100644
--- a/intern/cycles/kernel/kernel_types.h
+++ b/intern/cycles/kernel/kernel_types.h
@@ -337,6 +337,7 @@ 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),
 #endif
 } PassType;
 
@@ -848,7 +849,8 @@ typedef struct KernelFilm {
 
 #ifdef __KERNEL_DEBUG__
 	int pass_bvh_traversal_steps;
-	int pass_pad3, pass_pad4, pass_pad5;
+	int pass_ray_bounces;
+	int pass_pad3, pass_pad4;
 #endif
 } KernelFilm;
 
@@ -987,6 +989,7 @@ 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_ray_bounces;
 } DebugData;
 #endif
 
diff --git a/intern/cycles/kernel/split/kernel_scene_intersect.h b/intern/cycles/kernel/split/kernel_scene_intersect.h
index 09e3e5ddd7e..c1e82c7a21b 100644
--- a/intern/cycles/kernel/split/kernel_scene_intersect.h
+++ b/intern/cycles/kernel/split/kernel_scene_intersect.h
@@ -124,6 +124,7 @@ ccl_device void kernel_scene_intersect(
 	if(state.flag & PATH_RAY_CAMERA) {
 		debug_data->num_bvh_traversal_steps += isect->num_traversal_steps;
 	}
+	debug_data->num_ray_bounces++;
 #endif
 
 	if(!hit) {