From 5e8cdfda92f267d1d778268e640c4847a1e6f62a Mon Sep 17 00:00:00 2001
From: Billy Laws <blaws05@gmail.com>
Date: Mon, 20 Feb 2023 17:32:21 +0000
Subject: [PATCH] Don't populate colour targets with an empty write mask

Avoids breaking VK spec in BOTW, as it has the same colour attachment bound twice, but the former is masked out entirely.
---
 .../gpu/interconnect/maxwell_3d/pipeline_state.cpp        | 8 ++++++--
 .../skyline/gpu/interconnect/maxwell_3d/pipeline_state.h  | 2 ++
 .../main/cpp/skyline/soc/gm20b/engines/maxwell/types.h    | 4 ++++
 3 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/app/src/main/cpp/skyline/gpu/interconnect/maxwell_3d/pipeline_state.cpp b/app/src/main/cpp/skyline/gpu/interconnect/maxwell_3d/pipeline_state.cpp
index c9abcfa0..771f2e93 100644
--- a/app/src/main/cpp/skyline/gpu/interconnect/maxwell_3d/pipeline_state.cpp
+++ b/app/src/main/cpp/skyline/gpu/interconnect/maxwell_3d/pipeline_state.cpp
@@ -300,6 +300,7 @@ namespace skyline::gpu::interconnect::maxwell3d {
     void ColorBlendState::Flush(PackedPipelineState &packedState) {
         packedState.logicOpEnable = engine->logicOp.enable;
         packedState.SetLogicOp(engine->logicOp.func);
+        writtenCtMask.reset();
 
         for (u32 i{}; i < engine::ColorTargetCount; i++) {
             auto ctWrite{[&]() {
@@ -315,6 +316,8 @@ namespace skyline::gpu::interconnect::maxwell3d {
                 packedState.SetAttachmentBlendState(i, enable, ctWrite, engine->blendPerTargets[i]);
             else
                 packedState.SetAttachmentBlendState(i, enable, ctWrite, engine->blend);
+
+            writtenCtMask.set(i, ctWrite.Any());
         }
     }
 
@@ -392,10 +395,12 @@ namespace skyline::gpu::interconnect::maxwell3d {
             shaderBinaries[i] = stage.binary;
         }
 
+        colorBlend.Update(packedState);
+
         colorAttachments.clear();
         packedState.colorRenderTargetFormats = {};
         for (size_t i{}; i < engine::ColorTargetCount; i++) {
-            if (i < ctSelect.count) {
+            if (i < ctSelect.count && colorBlend.Get().writtenCtMask.test(i)) {
                 const auto &rt{colorRenderTargets[ctSelect[i]].UpdateGet(ctx, packedState)};
                 const auto view{rt.view.get()};
                 packedState.SetColorRenderTargetFormat(ctSelect[i], rt.format);
@@ -417,7 +422,6 @@ namespace skyline::gpu::interconnect::maxwell3d {
         tessellation.Update(packedState);
         rasterization.Update(packedState);
         depthStencil.Update(packedState);
-        colorBlend.Update(packedState);
         transformFeedback.Update(packedState);
         globalShaderConfig.Update(packedState);
 
diff --git a/app/src/main/cpp/skyline/gpu/interconnect/maxwell_3d/pipeline_state.h b/app/src/main/cpp/skyline/gpu/interconnect/maxwell_3d/pipeline_state.h
index 31e89dd9..5f6a84e3 100644
--- a/app/src/main/cpp/skyline/gpu/interconnect/maxwell_3d/pipeline_state.h
+++ b/app/src/main/cpp/skyline/gpu/interconnect/maxwell_3d/pipeline_state.h
@@ -234,6 +234,8 @@ namespace skyline::gpu::interconnect::maxwell3d {
         dirty::BoundSubresource<EngineRegisters> engine;
 
       public:
+        std::bitset<engine::ColorTargetCount> writtenCtMask{};
+
         ColorBlendState(dirty::Handle dirtyHandle, DirtyManager &manager, const EngineRegisters &engine);
 
         void Flush(PackedPipelineState &packedState);
diff --git a/app/src/main/cpp/skyline/soc/gm20b/engines/maxwell/types.h b/app/src/main/cpp/skyline/soc/gm20b/engines/maxwell/types.h
index b239fd43..e75d4669 100644
--- a/app/src/main/cpp/skyline/soc/gm20b/engines/maxwell/types.h
+++ b/app/src/main/cpp/skyline/soc/gm20b/engines/maxwell/types.h
@@ -718,6 +718,10 @@ namespace skyline::soc::gm20b::engine::maxwell3d::type {
     static_assert(sizeof(ViewportClipControl) == sizeof(u32));
 
     union CtWrite {
+        bool Any() const {
+            return rEnable || gEnable || bEnable || aEnable;
+        }
+
         u32 raw;
 
         struct {