nx2: decode sRGB in the upscale fallback when the program does

Splatoon Raiders' upscaler program ends by decoding its result from
sRGB to linear (HSETP2 against 0.04045, HMUL2 by 2.4 between MUFU.LG2
and MUFU.EX2) before its surface store. The bilinear copy that stands in
for it while HMMA isn't emulated wrote the sRGB input as-is, so the
later passes encoded it a second time: outdoor scenes were washed out,
with a pale sky and a white haze.

When the program carries those two immediates, the copy now decodes
like it, through a new copy operation of the blit helper (a fragment
shader with the piecewise sRGB decode). Programs without them, such as
Kirby Air Riders' upscaler, keep the plain copy. The OpenGL backend
ignores the operation.

2 files changed, 7 insertions, 1 deletions

diff --git a/src/video_core/renderer_vulkan/blit_image.cpp b/src/video_core/renderer_vulkan/blit_image.cpp
index edd151b563..506daef11e 100644
--- a/src/video_core/renderer_vulkan/blit_image.cpp
+++ b/src/video_core/renderer_vulkan/blit_image.cpp
@@ -11,6 +11,7 @@
 #include "common/div_ceil.h"
 #include "common/settings.h"
 #include "video_core/host_shaders/blit_color_float_frag_spv.h"
+#include "video_core/host_shaders/blit_color_srgb_to_linear_frag_spv.h"
 #include "video_core/host_shaders/blit_color_msaa_frag_spv.h"
 #include "video_core/host_shaders/blit_depth_frag_spv.h"
 #include "video_core/host_shaders/blit_depth_msaa_frag_spv.h"
@@ -670,6 +671,7 @@ BlitImageHelper::BlitImageHelper(const Device& device_, Scheduler& scheduler_,
       full_screen_vert(BuildShader(device, FULL_SCREEN_TRIANGLE_VERT_SPV)),
       blit_color_to_color_frag(BuildShader(device, BLIT_COLOR_FLOAT_FRAG_SPV)),
       temporal_upscale_frag(BuildShader(device, TEMPORAL_UPSCALE_FRAG_SPV)),
+      blit_color_srgb_to_linear_frag(BuildShader(device, BLIT_COLOR_SRGB_TO_LINEAR_FRAG_SPV)),
       blit_color_msaa_frag(BuildShader(device, BLIT_COLOR_MSAA_FRAG_SPV)),
       blit_depth_stencil_frag(device.IsExtShaderStencilExportSupported()
                              ? BuildShader(device, VULKAN_BLIT_DEPTH_STENCIL_FRAG_SPV)
@@ -1331,7 +1333,10 @@ VkPipeline BlitImageHelper::FindOrEmplaceColorPipeline(const BlitImagePipelineKe
     }
     blit_color_keys.push_back(key);
 
-    const std::array stages = MakeStages(*full_screen_vert, *blit_color_to_color_frag);
+    const bool srgb_to_linear =
+        key.operation == Tegra::Engines::Fermi2D::Operation::SrcCopySrgbToLinear;
+    const std::array stages = MakeStages(
+        *full_screen_vert, srgb_to_linear ? *blit_color_srgb_to_linear_frag : *blit_color_to_color_frag);
     const VkPipelineColorBlendAttachmentState blend_attachment{
         .blendEnable = VK_FALSE,
         .srcColorBlendFactor = VK_BLEND_FACTOR_ZERO,
diff --git a/src/video_core/renderer_vulkan/blit_image.h b/src/video_core/renderer_vulkan/blit_image.h
index 303beeea5c..4741f9fe45 100644
--- a/src/video_core/renderer_vulkan/blit_image.h
+++ b/src/video_core/renderer_vulkan/blit_image.h
@@ -229,6 +229,7 @@ private:
     vk::ShaderModule full_screen_vert;
     vk::ShaderModule blit_color_to_color_frag;
     vk::ShaderModule temporal_upscale_frag;
+    vk::ShaderModule blit_color_srgb_to_linear_frag;
     vk::ShaderModule blit_color_msaa_frag;
     vk::ShaderModule blit_depth_stencil_frag;
     vk::ShaderModule blit_depth_frag;