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, 13 insertions, 0 deletions

diff --git a/intern/cycles/render/film.cpp b/intern/cycles/render/film.cpp
index 09973e8bc86..19f959d4ea1 100644
--- a/intern/cycles/render/film.cpp
+++ b/intern/cycles/render/film.cpp
@@ -146,6 +146,12 @@ void Pass::add(PassType type, vector<Pass>& passes)
 		case PASS_LIGHT:
 			/* ignores */
 			break;
+#ifdef WITH_CYCLES_DEBUG
+		case PASS_BVH_TRAVERSAL_STEPS:
+			pass.components = 1;
+			pass.exposure = false;
+			break;
+#endif
 	}
 
 	passes.push_back(pass);
@@ -388,6 +394,13 @@ void Film::device_update(Device *device, DeviceScene *dscene, Scene *scene)
 			case PASS_LIGHT:
 				kfilm->use_light_pass = 1;
 				break;
+
+#ifdef WITH_CYCLES_DEBUG
+			case PASS_BVH_TRAVERSAL_STEPS:
+				kfilm->pass_bvh_traversal_steps = kfilm->pass_stride;
+				break;
+#endif
+
 			case PASS_NONE:
 				break;
 		}