Add support for alpha to coverage dithering (#3069)

* Add support for alpha to coverage dithering

* Shader cache version bump

* Fix wrong alpha register

* Ensure support buffer is cleared

* New shader specialization based approach

2 files changed, 27 insertions, 5 deletions

diff --git a/Ryujinx.Graphics.Gpu/Engine/Threed/StateUpdater.cs b/Ryujinx.Graphics.Gpu/Engine/Threed/StateUpdater.cs
index c64c760a..2f5d4fc5 100644
--- a/Ryujinx.Graphics.Gpu/Engine/Threed/StateUpdater.cs
+++ b/Ryujinx.Graphics.Gpu/Engine/Threed/StateUpdater.cs
@@ -166,7 +166,11 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
                     nameof(ThreedClassState.BlendEnable),
                     nameof(ThreedClassState.BlendState)),
 
-                new StateUpdateCallbackEntry(UpdateLogicOpState, nameof(ThreedClassState.LogicOpState))
+                new StateUpdateCallbackEntry(UpdateLogicOpState, nameof(ThreedClassState.LogicOpState)),
+
+                new StateUpdateCallbackEntry(UpdateMultisampleState,
+                    nameof(ThreedClassState.AlphaToCoverageDitherEnable),
+                    nameof(ThreedClassState.MultisampleControl))
             });
         }
 
@@ -1093,6 +1097,20 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
         }
 
         /// <summary>
+        /// Updates multisample state, based on guest state.
+        /// </summary>
+        private void UpdateMultisampleState()
+        {
+            bool alphaToCoverageEnable = (_state.State.MultisampleControl & 1) != 0;
+            bool alphaToOneEnable = (_state.State.MultisampleControl & 0x10) != 0;
+
+            _context.Renderer.Pipeline.SetMultisampleState(new MultisampleDescriptor(
+                alphaToCoverageEnable,
+                _state.State.AlphaToCoverageDitherEnable,
+                alphaToOneEnable));
+        }
+
+        /// <summary>
         /// Updates host shaders based on the guest GPU state.
         /// </summary>
         private void UpdateShaderState()
@@ -1231,7 +1249,9 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
                 _state.State.EarlyZForce,
                 _drawState.Topology,
                 _state.State.TessMode,
-                _state.State.ViewportTransformEnable == 0);
+                _state.State.ViewportTransformEnable == 0,
+                (_state.State.MultisampleControl & 1) != 0,
+                _state.State.AlphaToCoverageDitherEnable);
         }
 
         /// <summary>
diff --git a/Ryujinx.Graphics.Gpu/Engine/Threed/ThreedClassState.cs b/Ryujinx.Graphics.Gpu/Engine/Threed/ThreedClassState.cs
index 81a22831..2a831356 100644
--- a/Ryujinx.Graphics.Gpu/Engine/Threed/ThreedClassState.cs
+++ b/Ryujinx.Graphics.Gpu/Engine/Threed/ThreedClassState.cs
@@ -767,7 +767,8 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
         public SamplerIndex SamplerIndex;
         public fixed uint Reserved1238[37];
         public Boolean32 DepthTestEnable;
-        public fixed uint Reserved12D0[5];
+        public fixed uint Reserved12D0[4];
+        public Boolean32 AlphaToCoverageDitherEnable;
         public Boolean32 BlendIndependent;
         public Boolean32 DepthWriteEnable;
         public Boolean32 AlphaTestEnable;
@@ -802,9 +803,10 @@ namespace Ryujinx.Graphics.Gpu.Engine.Threed
         public Boolean32 PointSpriteEnable;
         public fixed uint Reserved1524[3];
         public uint ResetCounter;
-        public uint Reserved1534;
+        public Boolean32 MultisampleEnable;
         public Boolean32 RtDepthStencilEnable;
-        public fixed uint Reserved153C[5];
+        public uint MultisampleControl;
+        public fixed uint Reserved1540[4];
         public GpuVa RenderEnableAddress;
         public Condition RenderEnableCondition;
         public PoolState SamplerPoolState;