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, 35 insertions, 0 deletions

diff --git a/intern/cycles/kernel/kernel_debug.h b/intern/cycles/kernel/kernel_debug.h
new file mode 100644
index 00000000000..81ce1e76420
--- /dev/null
+++ b/intern/cycles/kernel/kernel_debug.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright 2011-2014 Blender Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+CCL_NAMESPACE_BEGIN
+
+ccl_device_inline void debug_data_init(DebugData *debug_data)
+{
+	debug_data->num_bvh_traversal_steps = 0;
+}
+
+ccl_device_inline void kernel_write_debug_passes(KernelGlobals *kg,
+                                                 ccl_global float *buffer,
+                                                 PathState *state,
+                                                 DebugData *debug_data,
+                                                 int sample)
+{
+	kernel_write_pass_float(buffer + kernel_data.film.pass_bvh_traversal_steps,
+	                        sample,
+	                        debug_data->num_bvh_traversal_steps);
+}
+
+CCL_NAMESPACE_END