Cycles: Implement denoising option for reducing noise in the rendered image

This commit contains the first part of the new Cycles denoising option,
which filters the resulting image using information gathered during rendering
to get rid of noise while preserving visual features as well as possible.

To use the option, enable it in the render layer options. The default settings
fit a wide range of scenes, but the user can tweak individual settings to
control the tradeoff between a noise-free image, image details, and calculation
time.

Note that the denoiser may still change in the future and that some features
are not implemented yet. The most important missing feature is animation
denoising, which uses information from multiple frames at once to produce a
flicker-free and smoother result. These features will be added in the future.

Finally, thanks to all the people who supported this project:

- Google (through the GSoC) and Theory Studios for sponsoring the development
- The authors of the papers I used for implementing the denoiser (more details
  on them will be included in the technical docs)
- The other Cycles devs for feedback on the code, especially Sergey for
  mentoring the GSoC project and Brecht for the code review!
- And of course the users who helped with testing, reported bugs and things
  that could and/or should work better!

4 files changed, 5 insertions, 4 deletions

diff --git a/source/blender/makesrna/intern/rna_render.c b/source/blender/makesrna/intern/rna_render.c
index 129cc591d9f..44dcb72264a 100644
--- a/source/blender/makesrna/intern/rna_render.c
+++ b/source/blender/makesrna/intern/rna_render.c
@@ -549,6 +549,7 @@ static void rna_def_render_engine(BlenderRNA *brna)
 	parm = RNA_def_pointer(func, "result", "RenderResult", "Result", "");
 	RNA_def_parameter_flags(parm, 0, PARM_REQUIRED);
 	RNA_def_boolean(func, "cancel", 0, "Cancel", "Don't mark tile as done, don't merge results unless forced");
+	RNA_def_boolean(func, "highlight", 0, "Highlight", "Don't mark tile as done yet");
 	RNA_def_boolean(func, "do_merge_results", 0, "Merge Results", "Merge results even if cancel=true");
 
 	func = RNA_def_function(srna, "add_pass", "RE_engine_add_pass");
diff --git a/source/blender/render/extern/include/RE_engine.h b/source/blender/render/extern/include/RE_engine.h
index 491d44b3a4e..52491673612 100644
--- a/source/blender/render/extern/include/RE_engine.h
+++ b/source/blender/render/extern/include/RE_engine.h
@@ -141,7 +141,7 @@ void RE_result_load_from_file(struct RenderResult *result, struct ReportList *re
 struct RenderResult *RE_engine_begin_result(RenderEngine *engine, int x, int y, int w, int h, const char *layername, const char *viewname);
 void RE_engine_update_result(RenderEngine *engine, struct RenderResult *result);
 void RE_engine_add_pass(RenderEngine *engine, const char *name, int channels, const char *chan_id, const char *layername);
-void RE_engine_end_result(RenderEngine *engine, struct RenderResult *result, int cancel, int merge_results);
+void RE_engine_end_result(RenderEngine *engine, struct RenderResult *result, int cancel, int highlight, int merge_results);
 
 const char *RE_engine_active_view_get(RenderEngine *engine);
 void RE_engine_active_view_set(RenderEngine *engine, const char *viewname);
diff --git a/source/blender/render/intern/source/external_engine.c b/source/blender/render/intern/source/external_engine.c
index 97413c31e16..ee6dc96276c 100644
--- a/source/blender/render/intern/source/external_engine.c
+++ b/source/blender/render/intern/source/external_engine.c
@@ -259,7 +259,7 @@ void RE_engine_add_pass(RenderEngine *engine, const char *name, int channels, co
 	render_result_add_pass(re->result, name, channels, chan_id, layername, NULL);
 }
 
-void RE_engine_end_result(RenderEngine *engine, RenderResult *result, int cancel, int merge_results)
+void RE_engine_end_result(RenderEngine *engine, RenderResult *result, int cancel, int highlight, int merge_results)
 {
 	Render *re = engine->re;
 
@@ -268,7 +268,7 @@ void RE_engine_end_result(RenderEngine *engine, RenderResult *result, int cancel
 	}
 
 	/* merge. on break, don't merge in result for preview renders, looks nicer */
-	if (!cancel) {
+	if (!highlight) {
 		/* for exr tile render, detect tiles that are done */
 		RenderPart *pa = get_part_from_result(re, result);
 
diff --git a/source/blenderplayer/bad_level_call_stubs/stubs.c b/source/blenderplayer/bad_level_call_stubs/stubs.c
index bbff6790c79..9393459a56c 100644
--- a/source/blenderplayer/bad_level_call_stubs/stubs.c
+++ b/source/blenderplayer/bad_level_call_stubs/stubs.c
@@ -655,7 +655,7 @@ void RE_engine_update_result(struct RenderEngine *engine, struct RenderResult *r
 void RE_engine_update_progress(struct RenderEngine *engine, float progress) RET_NONE
 void RE_engine_set_error_message(RenderEngine *engine, const char *msg) RET_NONE
 void RE_engine_add_pass(RenderEngine *engine, const char *name, int channels, const char *chan_id, const char *layername) RET_NONE
-void RE_engine_end_result(RenderEngine *engine, struct RenderResult *result, int cancel, int merge_results) RET_NONE
+void RE_engine_end_result(RenderEngine *engine, struct RenderResult *result, int cancel, int highlight, int merge_results) RET_NONE
 void RE_engine_update_stats(RenderEngine *engine, const char *stats, const char *info) RET_NONE
 void RE_layer_load_from_file(struct RenderLayer *layer, struct ReportList *reports, const char *filename, int x, int y) RET_NONE
 void RE_result_load_from_file(struct RenderResult *result, struct ReportList *reports, const char *filename) RET_NONE