Cycles: Add support for debug passes

Currently only summed number of traversal steps and intersections used by the
camera ray intersection pass is implemented, but in the future we will support
more debug passes which would help checking what things makes the scene slow.
Example of such extra passes could be number of bounces, time spent on the
shader tree evaluation and so.

Implementation from the Cycles side is pretty much straightforward, could only
mention here that it's a build-time option disabled by default.

From the blender side it's implemented as a PASS_DEBUG with several subtypes
possible. This way we don't need to create an extra DNA pass type for each of
the debug passes, saving us a bits.

Reviewers: campbellbarton

Reviewed By: campbellbarton

Differential Revision: https://developer.blender.org/D813

1 files changed, 34 insertions, 0 deletions

diff --git a/intern/cycles/kernel/kernel_path.h b/intern/cycles/kernel/kernel_path.h
index e68a8370012..0e07d8a95f8 100644
--- a/intern/cycles/kernel/kernel_path.h
+++ b/intern/cycles/kernel/kernel_path.h
@@ -45,6 +45,10 @@
 #include "kernel_path_surface.h"
 #include "kernel_path_volume.h"
 
+#ifdef __KERNEL_DEBUG__
+#  include "kernel_debug.h"
+#endif
+
 CCL_NAMESPACE_BEGIN
 
 ccl_device void kernel_path_indirect(KernelGlobals *kg, RNG *rng, Ray ray,
@@ -473,6 +477,11 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
 	PathState state;
 	path_state_init(kg, &state, rng, sample, &ray);
 
+#ifdef __KERNEL_DEBUG__
+	DebugData debug_data;
+	debug_data_init(&debug_data);
+#endif
+
 	/* path iteration */
 	for(;;) {
 		/* intersect scene */
@@ -499,6 +508,12 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
 		bool hit = scene_intersect(kg, &ray, visibility, &isect, NULL, 0.0f, 0.0f);
 #endif
 
+#ifdef __KERNEL_DEBUG__
+		if(state.flag & PATH_RAY_CAMERA) {
+			debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
+		}
+#endif
+
 #ifdef __LAMP_MIS__
 		if(kernel_data.integrator.use_lamp_mis && !(state.flag & PATH_RAY_CAMERA)) {
 			/* ray starting from previous non-transparent bounce */
@@ -719,6 +734,10 @@ ccl_device float4 kernel_path_integrate(KernelGlobals *kg, RNG *rng, int sample,
 
 	kernel_write_light_passes(kg, buffer, &L, sample);
 
+#ifdef __KERNEL_DEBUG__
+	kernel_write_debug_passes(kg, buffer, &state, &debug_data, sample);
+#endif
+
 	return make_float4(L_sum.x, L_sum.y, L_sum.z, 1.0f - L_transparent);
 }
 
@@ -864,6 +883,11 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
 	PathState state;
 	path_state_init(kg, &state, rng, sample, &ray);
 
+#ifdef __KERNEL_DEBUG__
+	DebugData debug_data;
+	debug_data_init(&debug_data);
+#endif
+
 	for(;;) {
 		/* intersect scene */
 		Intersection isect;
@@ -889,6 +913,12 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
 		bool hit = scene_intersect(kg, &ray, visibility, &isect, NULL, 0.0f, 0.0f);
 #endif
 
+#ifdef __KERNEL_DEBUG__
+		if(state.flag & PATH_RAY_CAMERA) {
+			debug_data.num_bvh_traversal_steps += isect.num_traversal_steps;
+		}
+#endif
+
 #ifdef __VOLUME__
 		/* volume attenuation, emission, scatter */
 		if(state.volume_stack[0].shader != SHADER_NONE) {
@@ -1144,6 +1174,10 @@ ccl_device float4 kernel_branched_path_integrate(KernelGlobals *kg, RNG *rng, in
 
 	kernel_write_light_passes(kg, buffer, &L, sample);
 
+#ifdef __KERNEL_DEBUG__
+	kernel_write_debug_passes(kg, buffer, &state, &debug_data, sample);
+#endif
+
 	return make_float4(L_sum.x, L_sum.y, L_sum.z, 1.0f - L_transparent);
 }