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

9 files changed, 70 insertions, 1 deletions

diff --git a/source/blender/makesdna/DNA_scene_types.h b/source/blender/makesdna/DNA_scene_types.h
index c8b8e4d52a4..ab13c704df4 100644
--- a/source/blender/makesdna/DNA_scene_types.h
+++ b/source/blender/makesdna/DNA_scene_types.h
@@ -242,6 +242,7 @@ typedef enum ScenePassType {
 	SCE_PASS_SUBSURFACE_DIRECT        = (1 << 28),
 	SCE_PASS_SUBSURFACE_INDIRECT      = (1 << 29),
 	SCE_PASS_SUBSURFACE_COLOR         = (1 << 30),
+	SCE_PASS_DEBUG                    = (1 << 31),  /* This is a virtual pass. */
 } ScenePassType;
 
 /* note, srl->passflag is treestore element 'nr' in outliner, short still... */
diff --git a/source/blender/makesrna/SConscript b/source/blender/makesrna/SConscript
index 898881076c4..c59e17f76df 100644
--- a/source/blender/makesrna/SConscript
+++ b/source/blender/makesrna/SConscript
@@ -117,6 +117,9 @@ if env['WITH_BF_OCEANSIM']:
 if env['WITH_BF_CYCLES']:
     defs.append('WITH_CYCLES')
 
+  if env['WITH_BF_CYCLES_DEBUG']:
+      defs.append('WITH_CYCLES_DEBUG')
+
 if env['WITH_BF_SDL']:
     defs.append('WITH_SDL')
 
diff --git a/source/blender/makesrna/intern/CMakeLists.txt b/source/blender/makesrna/intern/CMakeLists.txt
index d62a2e2c76e..c5f62439b9e 100644
--- a/source/blender/makesrna/intern/CMakeLists.txt
+++ b/source/blender/makesrna/intern/CMakeLists.txt
@@ -155,6 +155,9 @@ set(INC_SYS
 
 if(WITH_CYCLES)
 	add_definitions(-DWITH_CYCLES)
+	if(WITH_CYCLES_DEBUG)
+		add_definitions(-DWITH_CYCLES_DEBUG)
+	endif()
 endif()
 
 if(WITH_PYTHON)
diff --git a/source/blender/makesrna/intern/SConscript b/source/blender/makesrna/intern/SConscript
index 179a332336e..9fda79feb74 100644
--- a/source/blender/makesrna/intern/SConscript
+++ b/source/blender/makesrna/intern/SConscript
@@ -140,6 +140,8 @@ if env['WITH_BF_COLLADA']:
 
 if env['WITH_BF_CYCLES']:
     defs.append('WITH_CYCLES')
+    if env['WITH_BF_CYCLES_DEBUG']:
+        defs.append('WITH_CYCLES_DEBUG')
 
 if env['WITH_BF_FREESTYLE']:
     defs.append('WITH_FREESTYLE')
diff --git a/source/blender/makesrna/intern/rna_render.c b/source/blender/makesrna/intern/rna_render.c
index 284377d34f9..c5750f56d28 100644
--- a/source/blender/makesrna/intern/rna_render.c
+++ b/source/blender/makesrna/intern/rna_render.c
@@ -71,6 +71,9 @@ EnumPropertyItem render_pass_type_items[] = {
 	{SCE_PASS_SUBSURFACE_DIRECT, "SUBSURFACE_DIRECT", 0, "Subsurface Direct", ""},
 	{SCE_PASS_SUBSURFACE_INDIRECT, "SUBSURFACE_INDIRECT", 0, "Subsurface Indirect", ""},
 	{SCE_PASS_SUBSURFACE_COLOR, "SUBSURFACE_COLOR", 0, "Subsurface Color", ""},
+#ifdef WITH_CYCLES_DEBUG
+	{SCE_PASS_DEBUG, "DEBUG", 0, "Pass used for render engine debugging", ""},
+#endif
 	{0, NULL, 0, NULL, NULL}
 };
 
@@ -683,6 +686,10 @@ static void rna_def_render_pass(BlenderRNA *brna)
 	StructRNA *srna;
 	PropertyRNA *prop;
 
+	static EnumPropertyItem render_pass_debug_type_items[] = {
+		{RENDER_PASS_DEBUG_BVH_TRAVERSAL_STEPS, "BVH_TRAVERSAL_STEPS", 0, "BVH Traversal Steps", ""},
+	};
+
 	srna = RNA_def_struct(brna, "RenderPass", NULL);
 	RNA_def_struct_ui_text(srna, "Render Pass", "");
 
@@ -712,6 +719,11 @@ static void rna_def_render_pass(BlenderRNA *brna)
 	RNA_def_property_dynamic_array_funcs(prop, "rna_RenderPass_rect_get_length");
 	RNA_def_property_float_funcs(prop, "rna_RenderPass_rect_get", "rna_RenderPass_rect_set", NULL);
 
+	prop = RNA_def_property(srna, "debug_type", PROP_ENUM, PROP_NONE);
+	RNA_def_property_enum_sdna(prop, NULL, "debug_type");
+	RNA_def_property_enum_items(prop, render_pass_debug_type_items);
+	RNA_def_property_clear_flag(prop, PROP_EDITABLE);
+
 	RNA_define_verify_sdna(1);
 }
 
diff --git a/source/blender/render/CMakeLists.txt b/source/blender/render/CMakeLists.txt
index 8e326e770fc..e516c954737 100644
--- a/source/blender/render/CMakeLists.txt
+++ b/source/blender/render/CMakeLists.txt
@@ -162,6 +162,10 @@ if(WITH_INTERNATIONAL)
 	add_definitions(-DWITH_INTERNATIONAL)
 endif()
 
+if(WITH_CYCLES AND WITH_CYCLES_DEBUG)
+	add_definitions(-DWITH_CYCLES_DEBUG)
+endif()
+
 if(APPLE)
 	# SSE math is enabled by default on x86_64
 	if(CMAKE_OSX_ARCHITECTURES MATCHES "i386")
diff --git a/source/blender/render/SConscript b/source/blender/render/SConscript
index 297e4fcecd4..297debabcb4 100644
--- a/source/blender/render/SConscript
+++ b/source/blender/render/SConscript
@@ -103,6 +103,9 @@ if env['WITH_BF_GAMEENGINE']:
 if env['WITH_BF_INTERNATIONAL']:
     defs.append('WITH_INTERNATIONAL')
 
+if env['WITH_BF_CYCLES'] and env['WITH_VF_CYCLES_DEBUG']:
+    defs.append('WITH_CYCLES_DEBUG')
+
 if env['OURPLATFORM'] in ('win32-vc', 'win32-mingw', 'linuxcross', 'win64-vc', 'win64-mingw'):
     incs += ' ' + env['BF_PTHREADS_INC']
 
diff --git a/source/blender/render/extern/include/RE_pipeline.h b/source/blender/render/extern/include/RE_pipeline.h
index 3b54de4c943..61795c2c173 100644
--- a/source/blender/render/extern/include/RE_pipeline.h
+++ b/source/blender/render/extern/include/RE_pipeline.h
@@ -72,8 +72,13 @@ typedef struct RenderPass {
 	char chan_id[8];	/* amount defined in openexr_multi.h */
 	float *rect;
 	int rectx, recty;
+	int debug_type;
 } RenderPass;
 
+enum {
+	RENDER_PASS_DEBUG_BVH_TRAVERSAL_STEPS = 0,
+};
+
 /* a renderlayer is a full image, but with all passes and samples */
 /* size of the rects is defined in RenderResult */
 /* after render, the Combined pass is in rectf, for renderlayers read from files it is a real pass */
diff --git a/source/blender/render/intern/source/render_result.c b/source/blender/render/intern/source/render_result.c
index d8410fbe257..24797521435 100644
--- a/source/blender/render/intern/source/render_result.c
+++ b/source/blender/render/intern/source/render_result.c
@@ -48,6 +48,9 @@
 #include "BKE_global.h"
 #include "BKE_main.h"
 #include "BKE_report.h"
+#ifdef WITH_CYCLES_DEBUG
+#  include "BKE_scene.h"
+#endif
 
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
@@ -402,7 +405,7 @@ static int passtype_from_name(const char *str)
 
 /********************************** New **************************************/
 
-static void render_layer_add_pass(RenderResult *rr, RenderLayer *rl, int channels, int passtype)
+static RenderPass *render_layer_add_pass(RenderResult *rr, RenderLayer *rl, int channels, int passtype)
 {
 	const char *typestr = get_pass_name(passtype, 0);
 	RenderPass *rpass = MEM_callocN(sizeof(RenderPass), typestr);
@@ -438,8 +441,34 @@ static void render_layer_add_pass(RenderResult *rr, RenderLayer *rl, int channel
 				rect[x] = 10e10;
 		}
 	}
+	return rpass;
 }
 
+#ifdef WITH_CYCLES_DEBUG
+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";
+	}
+	return "Unknown";
+}
+
+static RenderPass *render_layer_add_debug_pass(RenderResult *rr,
+                                               RenderLayer *rl,
+                                               int channels,
+                                               int pass_type,
+                                               int debug_type)
+{
+	RenderPass *rpass = render_layer_add_pass(rr, rl, channels, pass_type);
+	rpass->debug_type = debug_type;
+	BLI_strncpy(rpass->name,
+	            debug_pass_type_name_get(debug_type),
+	            sizeof(rpass->name));
+	return rpass;
+}
+#endif
+
 /* called by main render as well for parts */
 /* will read info from Render *re to define layers */
 /* called in threads */
@@ -578,6 +607,13 @@ RenderResult *render_result_new(Render *re, rcti *partrct, int crop, int savebuf
 			render_layer_add_pass(rr, rl, 3, SCE_PASS_SUBSURFACE_INDIRECT);
 		if (srl->passflag  & SCE_PASS_SUBSURFACE_COLOR)
 			render_layer_add_pass(rr, rl, 3, SCE_PASS_SUBSURFACE_COLOR);
+
+#ifdef WITH_CYCLES_DEBUG
+		if(BKE_scene_use_new_shading_nodes(re->scene)) {
+			render_layer_add_debug_pass(rr, rl, 1, SCE_PASS_DEBUG,
+			        RENDER_PASS_DEBUG_BVH_TRAVERSAL_STEPS);
+		}
+#endif
 	}
 	/* sss, previewrender and envmap don't do layers, so we make a default one */
 	if (BLI_listbase_is_empty(&rr->layers) && !(layername && layername[0])) {