Cycles: Optionally output luminance from the shader evaluation kernel

This makes it possible to move some parts of evaluation from host to the device
and hopefully reduce memory usage by avoid having full RGBA buffer on the host.

Reviewers: juicyfruit, lukasstockner97, brecht

Reviewed By: lukasstockner97, brecht

Differential Revision: https://developer.blender.org/D1702

2 files changed, 4 insertions, 0 deletions

diff --git a/intern/cycles/kernel/kernels/cpu/kernel_cpu.h b/intern/cycles/kernel/kernels/cpu/kernel_cpu.h
index 2560c6d8dee..1ce1e41272b 100644
--- a/intern/cycles/kernel/kernels/cpu/kernel_cpu.h
+++ b/intern/cycles/kernel/kernels/cpu/kernel_cpu.h
@@ -42,6 +42,7 @@ void KERNEL_FUNCTION_FULL_NAME(convert_to_half_float)(KernelGlobals *kg,
 void KERNEL_FUNCTION_FULL_NAME(shader)(KernelGlobals *kg,
                                        uint4 *input,
                                        float4 *output,
+                                       float *output_luma,
                                        int type,
                                        int i,
                                        int offset,
diff --git a/intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h b/intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h
index 693285ec3a8..0249610b381 100644
--- a/intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h
+++ b/intern/cycles/kernel/kernels/cpu/kernel_cpu_impl.h
@@ -99,12 +99,14 @@ void KERNEL_FUNCTION_FULL_NAME(convert_to_half_float)(KernelGlobals *kg,
 void KERNEL_FUNCTION_FULL_NAME(shader)(KernelGlobals *kg,
                                        uint4 *input,
                                        float4 *output,
+                                       float *output_luma,
                                        int type,
                                        int i,
                                        int offset,
                                        int sample)
 {
 	if(type >= SHADER_EVAL_BAKE) {
+		kernel_assert(output_luma == NULL);
 		kernel_bake_evaluate(kg,
 		                     input,
 		                     output,
@@ -117,6 +119,7 @@ void KERNEL_FUNCTION_FULL_NAME(shader)(KernelGlobals *kg,
 		kernel_shader_evaluate(kg,
 		                       input,
 		                       output,
+		                       output_luma,
 		                       (ShaderEvalType)type,
 		                       i,
 		                       sample);