Cycles: Expose noisy image pass by default when rendering with denoiser

Apparently quite a few users would like to have the noisy pass available when using the denoiser, and since it's being generated anyways we might as well expose it by default.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D3608

1 files changed, 25 insertions, 10 deletions

diff --git a/intern/cycles/render/buffers.cpp b/intern/cycles/render/buffers.cpp
index 4cd8b3726d3..e6021f4b37d 100644
--- a/intern/cycles/render/buffers.cpp
+++ b/intern/cycles/render/buffers.cpp
@@ -160,11 +160,12 @@ bool RenderBuffers::get_denoising_pass_rect(int offset, float exposure, int samp
 	                (offset == DENOISING_PASS_DEPTH_VAR) ||
 	                (offset == DENOISING_PASS_COLOR_VAR);
 
+	float scale_exposure = scale;
 	if(offset == DENOISING_PASS_COLOR || offset == DENOISING_PASS_CLEAN) {
-		scale *= exposure;
+		scale_exposure *= exposure;
 	}
 	else if(offset == DENOISING_PASS_COLOR_VAR) {
-		scale *= exposure*exposure;
+		scale_exposure *= exposure*exposure;
 	}
 
 	offset += params.get_denoising_offset();
@@ -181,14 +182,14 @@ bool RenderBuffers::get_denoising_pass_rect(int offset, float exposure, int samp
 
 		if(components == 1) {
 			for(int i = 0; i < size; i++, mean += pass_stride, var += pass_stride, pixels++) {
-				pixels[0] = max(0.0f, var[0] - mean[0]*mean[0]*invsample)*scale;
+				pixels[0] = max(0.0f, var[0] - mean[0]*mean[0]*invsample)*scale_exposure;
 			}
 		}
 		else if(components == 3) {
 			for(int i = 0; i < size; i++, mean += pass_stride, var += pass_stride, pixels += 3) {
-				pixels[0] = max(0.0f, var[0] - mean[0]*mean[0]*invsample)*scale;
-				pixels[1] = max(0.0f, var[1] - mean[1]*mean[1]*invsample)*scale;
-				pixels[2] = max(0.0f, var[2] - mean[2]*mean[2]*invsample)*scale;
+				pixels[0] = max(0.0f, var[0] - mean[0]*mean[0]*invsample)*scale_exposure;
+				pixels[1] = max(0.0f, var[1] - mean[1]*mean[1]*invsample)*scale_exposure;
+				pixels[2] = max(0.0f, var[2] - mean[2]*mean[2]*invsample)*scale_exposure;
 			}
 		}
 		else {
@@ -200,14 +201,28 @@ bool RenderBuffers::get_denoising_pass_rect(int offset, float exposure, int samp
 
 		if(components == 1) {
 			for(int i = 0; i < size; i++, in += pass_stride, pixels++) {
-				pixels[0] = in[0]*scale;
+				pixels[0] = in[0]*scale_exposure;
 			}
 		}
 		else if(components == 3) {
 			for(int i = 0; i < size; i++, in += pass_stride, pixels += 3) {
-				pixels[0] = in[0]*scale;
-				pixels[1] = in[1]*scale;
-				pixels[2] = in[2]*scale;
+				pixels[0] = in[0]*scale_exposure;
+				pixels[1] = in[1]*scale_exposure;
+				pixels[2] = in[2]*scale_exposure;
+			}
+		}
+		else if(components == 4) {
+			assert(offset == DENOISING_PASS_COLOR);
+
+			/* Since the alpha channel is not involved in denoising, output the Combined alpha channel. */
+			assert(params.passes[0].type == PASS_COMBINED);
+			float *in_combined = buffer.data();
+
+			for(int i = 0; i < size; i++, in += pass_stride, in_combined += pass_stride, pixels += 4) {
+				pixels[0] = in[0]*scale_exposure;
+				pixels[1] = in[1]*scale_exposure;
+				pixels[2] = in[2]*scale_exposure;
+				pixels[3] = saturate(in_combined[3]*scale);
 			}
 		}
 		else {