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!

1 files changed, 38 insertions, 41 deletions

diff --git a/intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h b/intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h
index 8c05dd1d9ef..b9d82781840 100644
--- a/intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h
+++ b/intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h
@@ -57,6 +57,11 @@
 #  include "kernel/split/kernel_buffer_update.h"
 #endif
 
+#ifdef KERNEL_STUB
+#  include "util/util_debug.h"
+#  define STUB_ASSERT(arch, name) assert(!(#name " kernel stub for architecture " #arch " was called!"))
+#endif
+
 CCL_NAMESPACE_BEGIN
 
 #ifndef __SPLIT_KERNEL__
@@ -71,7 +76,10 @@ void KERNEL_FUNCTION_FULL_NAME(path_trace)(KernelGlobals *kg,
                                            int offset,
                                            int stride)
 {
-#ifdef __BRANCHED_PATH__
+#ifdef KERNEL_STUB
+	STUB_ASSERT(KERNEL_ARCH, path_trace);
+#else
+#  ifdef __BRANCHED_PATH__
 	if(kernel_data.integrator.branched) {
 		kernel_branched_path_trace(kg,
 		                           buffer,
@@ -82,10 +90,11 @@ void KERNEL_FUNCTION_FULL_NAME(path_trace)(KernelGlobals *kg,
 		                           stride);
 	}
 	else
-#endif
+#  endif
 	{
 		kernel_path_trace(kg, buffer, rng_state, sample, x, y, offset, stride);
 	}
+#endif /* KERNEL_STUB */
 }
 
 /* Film */
@@ -98,6 +107,9 @@ void KERNEL_FUNCTION_FULL_NAME(convert_to_byte)(KernelGlobals *kg,
                                                 int offset,
                                                 int stride)
 {
+#ifdef KERNEL_STUB
+	STUB_ASSERT(KERNEL_ARCH, convert_to_byte);
+#else
 	kernel_film_convert_to_byte(kg,
 	                            rgba,
 	                            buffer,
@@ -105,6 +117,7 @@ void KERNEL_FUNCTION_FULL_NAME(convert_to_byte)(KernelGlobals *kg,
 	                            x, y,
 	                            offset,
 	                            stride);
+#endif /* KERNEL_STUB */
 }
 
 void KERNEL_FUNCTION_FULL_NAME(convert_to_half_float)(KernelGlobals *kg,
@@ -115,6 +128,9 @@ void KERNEL_FUNCTION_FULL_NAME(convert_to_half_float)(KernelGlobals *kg,
                                                       int offset,
                                                       int stride)
 {
+#ifdef KERNEL_STUB
+	STUB_ASSERT(KERNEL_ARCH, convert_to_half_float);
+#else
 	kernel_film_convert_to_half_float(kg,
 	                                  rgba,
 	                                  buffer,
@@ -122,6 +138,7 @@ void KERNEL_FUNCTION_FULL_NAME(convert_to_half_float)(KernelGlobals *kg,
 	                                  x, y,
 	                                  offset,
 	                                  stride);
+#endif /* KERNEL_STUB */
 }
 
 /* Shader Evaluate */
@@ -136,9 +153,12 @@ void KERNEL_FUNCTION_FULL_NAME(shader)(KernelGlobals *kg,
                                        int offset,
                                        int sample)
 {
+#ifdef KERNEL_STUB
+	STUB_ASSERT(KERNEL_ARCH, shader);
+#else
 	if(type >= SHADER_EVAL_BAKE) {
 		kernel_assert(output_luma == NULL);
-#ifdef __BAKING__
+#  ifdef __BAKING__
 		kernel_bake_evaluate(kg,
 		                     input,
 		                     output,
@@ -147,7 +167,7 @@ void KERNEL_FUNCTION_FULL_NAME(shader)(KernelGlobals *kg,
 		                     i,
 		                     offset,
 		                     sample);
-#endif
+#  endif
 	}
 	else {
 		kernel_shader_evaluate(kg,
@@ -158,17 +178,26 @@ void KERNEL_FUNCTION_FULL_NAME(shader)(KernelGlobals *kg,
 		                       i,
 		                       sample);
 	}
+#endif /* KERNEL_STUB */
 }
 
 #else  /* __SPLIT_KERNEL__ */
 
 /* Split Kernel Path Tracing */
 
-#define DEFINE_SPLIT_KERNEL_FUNCTION(name) \
+#ifdef KERNEL_STUB
+#  define DEFINE_SPLIT_KERNEL_FUNCTION(name) \
+	void KERNEL_FUNCTION_FULL_NAME(name)(KernelGlobals *kg, KernelData* /*data*/) \
+	{ \
+		STUB_ASSERT(KERNEL_ARCH, name); \
+	}
+#else
+#  define DEFINE_SPLIT_KERNEL_FUNCTION(name) \
 	void KERNEL_FUNCTION_FULL_NAME(name)(KernelGlobals *kg, KernelData* /*data*/) \
 	{ \
 		kernel_##name(kg); \
 	}
+#endif /* KERNEL_STUB */
 
 #define DEFINE_SPLIT_KERNEL_FUNCTION_LOCALS(name, type) \
 	void KERNEL_FUNCTION_FULL_NAME(name)(KernelGlobals *kg, KernelData* /*data*/) \
@@ -194,42 +223,10 @@ DEFINE_SPLIT_KERNEL_FUNCTION(shadow_blocked_dl)
 DEFINE_SPLIT_KERNEL_FUNCTION_LOCALS(next_iteration_setup, uint)
 DEFINE_SPLIT_KERNEL_FUNCTION(indirect_subsurface)
 DEFINE_SPLIT_KERNEL_FUNCTION_LOCALS(buffer_update, uint)
-
-void KERNEL_FUNCTION_FULL_NAME(register_functions)(void(*reg)(const char* name, void* func))
-{
-#define REGISTER_NAME_STRING(name) #name
-#define REGISTER_EVAL_NAME(name) REGISTER_NAME_STRING(name)
-#define REGISTER(name) reg(REGISTER_EVAL_NAME(KERNEL_FUNCTION_FULL_NAME(name)), (void*)KERNEL_FUNCTION_FULL_NAME(name));
-
-	REGISTER(path_trace);
-	REGISTER(convert_to_byte);
-	REGISTER(convert_to_half_float);
-	REGISTER(shader);
-
-	REGISTER(data_init);
-	REGISTER(path_init);
-	REGISTER(scene_intersect);
-	REGISTER(lamp_emission);
-	REGISTER(do_volume);
-	REGISTER(queue_enqueue);
-	REGISTER(indirect_background);
-	REGISTER(shader_setup);
-	REGISTER(shader_sort);
-	REGISTER(shader_eval);
-	REGISTER(holdout_emission_blurring_pathtermination_ao);
-	REGISTER(subsurface_scatter);
-	REGISTER(direct_lighting);
-	REGISTER(shadow_blocked_ao);
-	REGISTER(shadow_blocked_dl);
-	REGISTER(next_iteration_setup);
-	REGISTER(indirect_subsurface);
-	REGISTER(buffer_update);
-
-#undef REGISTER
-#undef REGISTER_EVAL_NAME
-#undef REGISTER_NAME_STRING
-}
-
 #endif  /* __SPLIT_KERNEL__ */
 
+#undef KERNEL_STUB
+#undef STUB_ASSERT
+#undef KERNEL_ARCH
+
 CCL_NAMESPACE_END