Implement Zero-Configuration Resolution Scaling (#1365)

* Initial implementation of Render Target Scaling

Works with most games I have. No GUI option right now, it is hardcoded.

Missing handling for texelFetch operation.

* Realtime Configuration, refactoring.

* texelFetch scaling on fragment shader (WIP)

* Improve Shader-Side changes.

* Fix potential crash when no color/depth bound

* Workaround random uses of textures in compute.

This was blacklisting textures in a few games despite causing no bugs. Will eventually add full support so this doesn't break anything.

* Fix scales oscillating when changing between non-native scales.

* Scaled textures on compute, cleanup, lazier uniform update.

* Cleanup.

* Fix stupidity

* Address Thog Feedback.

* Cover most of GDK's feedback (two comments remain)

* Fix bad rename

* Move IsDepthStencil to FormatExtensions, add docs.

* Fix default config, square texture detection.

* Three final fixes:

- Nearest copy when texture is integer format.
- Texture2D -> Texture3D copy correctly blacklists the texture before trying an unscaled copy (caused driver error)
- Discount small textures.

* Remove scale threshold.

Not needed right now - we'll see if we run into problems.

* All CPU modification blacklists scale.

* Fix comment.

6 files changed, 100 insertions, 3 deletions

diff --git a/Ryujinx.Graphics.Shader/CodeGen/Glsl/CodeGenContext.cs b/Ryujinx.Graphics.Shader/CodeGen/Glsl/CodeGenContext.cs
index 6bef8e6c..91ab7ad5 100644
--- a/Ryujinx.Graphics.Shader/CodeGen/Glsl/CodeGenContext.cs
+++ b/Ryujinx.Graphics.Shader/CodeGen/Glsl/CodeGenContext.cs
@@ -1,3 +1,5 @@
+using Ryujinx.Graphics.Shader.IntermediateRepresentation;
+using Ryujinx.Graphics.Shader.StructuredIr;
 using Ryujinx.Graphics.Shader.Translation;
 using System.Collections.Generic;
 using System.Text;
@@ -75,6 +77,21 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl
             AppendLine("}" + suffix);
         }
 
+        public int FindTextureDescriptorIndex(AstTextureOperation texOp)
+        {
+            AstOperand operand = texOp.GetSource(0) as AstOperand;
+            bool bindless = (texOp.Flags & TextureFlags.Bindless) > 0;
+
+            int cBufSlot = bindless ? operand.CbufSlot : 0;
+            int cBufOffset = bindless ? operand.CbufOffset : 0;
+
+            return TextureDescriptors.FindIndex(descriptor => 
+                descriptor.Type == texOp.Type && 
+                descriptor.HandleIndex == texOp.Handle && 
+                descriptor.CbufSlot == cBufSlot &&
+                descriptor.CbufOffset == cBufOffset);
+        }
+
         private void UpdateIndentation()
         {
             _indentation = GetIndentation(_level);
diff --git a/Ryujinx.Graphics.Shader/CodeGen/Glsl/Declarations.cs b/Ryujinx.Graphics.Shader/CodeGen/Glsl/Declarations.cs
index bd947ab7..f9d61928 100644
--- a/Ryujinx.Graphics.Shader/CodeGen/Glsl/Declarations.cs
+++ b/Ryujinx.Graphics.Shader/CodeGen/Glsl/Declarations.cs
@@ -137,6 +137,14 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl
                 context.AppendLine();
             }
 
+            if (context.Config.Stage == ShaderStage.Fragment || context.Config.Stage == ShaderStage.Compute)
+            {
+                if (DeclareRenderScale(context))
+                {
+                    context.AppendLine();
+                }
+            }
+
             if ((info.HelperFunctionsMask & HelperFunctionsMask.MultiplyHighS32) != 0)
             {
                 AppendHelperFunction(context, "Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/MultiplyHighS32.glsl");
@@ -219,6 +227,33 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl
             }
         }
 
+        private static bool DeclareRenderScale(CodeGenContext context)
+        {
+            if ((context.Config.UsedFeatures & (FeatureFlags.FragCoordXY | FeatureFlags.IntegerSampling)) != 0)
+            {
+                string stage = OperandManager.GetShaderStagePrefix(context.Config.Stage);
+
+                int scaleElements = context.TextureDescriptors.Count;
+                
+                if (context.Config.Stage == ShaderStage.Fragment)
+                {
+                    scaleElements++; // Also includes render target scale, for gl_FragCoord.
+                }
+
+                context.AppendLine($"uniform float {stage}_renderScale[{scaleElements}];");
+
+                if (context.Config.UsedFeatures.HasFlag(FeatureFlags.IntegerSampling))
+                {
+                    context.AppendLine();
+                    AppendHelperFunction(context, $"Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/TexelFetchScale_{stage}.glsl");
+                }
+
+                return true;
+            }
+
+            return false;
+        }
+
         private static void DeclareStorages(CodeGenContext context, StructuredProgramInfo info)
         {
             string sbName = OperandManager.GetShaderStagePrefix(context.Config.Stage);
diff --git a/Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/TexelFetchScale_cp.glsl b/Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/TexelFetchScale_cp.glsl
new file mode 100644
index 00000000..381566d3
--- /dev/null
+++ b/Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/TexelFetchScale_cp.glsl
@@ -0,0 +1,7 @@
+ivec2 Helper_TexelFetchScale(ivec2 inputVec, int samplerIndex) {
+    float scale = cp_renderScale[samplerIndex];
+    if (scale == 1.0) {
+        return inputVec;
+    }
+    return ivec2(vec2(inputVec) * scale);
+}
\ No newline at end of file
diff --git a/Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/TexelFetchScale_fp.glsl b/Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/TexelFetchScale_fp.glsl
new file mode 100644
index 00000000..4efaa65a
--- /dev/null
+++ b/Ryujinx.Graphics.Shader/CodeGen/Glsl/HelperFunctions/TexelFetchScale_fp.glsl
@@ -0,0 +1,11 @@
+ivec2 Helper_TexelFetchScale(ivec2 inputVec, int samplerIndex) {
+    float scale = fp_renderScale[1 + samplerIndex];
+    if (scale == 1.0) {
+        return inputVec;
+    }
+    if (scale < 0.0) { // If less than 0, try interpolate between texels by using the screen position.
+        return ivec2(vec2(inputVec) * (-scale) + mod(gl_FragCoord.xy, -scale));
+    } else {
+        return ivec2(vec2(inputVec) * scale);
+    }
+}
\ No newline at end of file
diff --git a/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs b/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs
index d05c77df..b951798d 100644
--- a/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs
+++ b/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs
@@ -390,7 +390,34 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl.Instructions
                 }
             }
 
-            Append(AssemblePVector(pCount));
+            string ApplyScaling(string vector)
+            {
+                if (intCoords)
+                {
+                    int index = context.FindTextureDescriptorIndex(texOp);
+
+                    if ((context.Config.Stage == ShaderStage.Fragment || context.Config.Stage == ShaderStage.Compute) &&
+                        (texOp.Flags & TextureFlags.Bindless) == 0 &&
+                        texOp.Type != SamplerType.Indexed &&
+                        pCount == 2)
+                    {
+                        return "Helper_TexelFetchScale(" + vector + ", " + index + ")";
+                    }
+                    else
+                    {
+                        // Resolution scaling cannot be applied to this texture right now.
+                        // Flag so that we know to blacklist scaling on related textures when binding them.
+
+                        TextureDescriptor descriptor = context.TextureDescriptors[index];
+                        descriptor.Flags |= TextureUsageFlags.ResScaleUnsupported;
+                        context.TextureDescriptors[index] = descriptor;
+                    }
+                }
+
+                return vector;
+            }
+
+            Append(ApplyScaling(AssemblePVector(pCount)));
 
             string AssembleDerivativesVector(int count)
             {
diff --git a/Ryujinx.Graphics.Shader/CodeGen/Glsl/OperandManager.cs b/Ryujinx.Graphics.Shader/CodeGen/Glsl/OperandManager.cs
index 4c3f802a..971284f4 100644
--- a/Ryujinx.Graphics.Shader/CodeGen/Glsl/OperandManager.cs
+++ b/Ryujinx.Graphics.Shader/CodeGen/Glsl/OperandManager.cs
@@ -185,8 +185,8 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl
                     {
                         switch (value & ~3)
                         {
-                            case AttributeConsts.PositionX: return "gl_FragCoord.x";
-                            case AttributeConsts.PositionY: return "gl_FragCoord.y";
+                            case AttributeConsts.PositionX: return "(gl_FragCoord.x / fp_renderScale[0])";
+                            case AttributeConsts.PositionY: return "(gl_FragCoord.y / fp_renderScale[0])";
                             case AttributeConsts.PositionZ: return "gl_FragCoord.z";
                             case AttributeConsts.PositionW: return "gl_FragCoord.w";
                         }