Shaders: Handle Ipa PASS argument as needed in Fragment Shaders (#392)

Ryujinx.Graphics/Gal/Shader/GlslDecompiler.cs

@@ -1026,7 +1026,31 @@ namespace Ryujinx.Graphics.Gal.Shader
             return "int(uint(" + GetOperExpr(Op, Op.OperandA) + "))";
         }
 
-        private string GetIpaExpr(ShaderIrOp Op) => GetSrcExpr(Op.OperandA);
+        private string GetIpaExpr(ShaderIrOp Op)
+        {
+            ShaderIrMetaIpa Meta = (ShaderIrMetaIpa)Op.MetaData;
+
+            ShaderIrOperAbuf Abuf = (ShaderIrOperAbuf)Op.OperandA;
+
+            if (Meta.Mode == ShaderIpaMode.Pass)
+            {
+                int Index = Abuf.Offs >> 4;
+                int Elem = (Abuf.Offs >> 2) & 3;
+
+                if (Decl.ShaderType == GalShaderType.Fragment && Index == GlslDecl.GlPositionVec4Index)
+                {
+                    switch (Elem)
+                    {
+                        case 0: return "gl_FragCoord.x";
+                        case 1: return "gl_FragCoord.y";
+                        case 2: return "gl_FragCoord.z";
+                        case 3: return "1";
+                    }
+                }
+            }
+
+            return GetSrcExpr(Op.OperandA);
+        }
 
         private string GetKilExpr(ShaderIrOp Op) => "discard";
 

Ryujinx.Graphics/Gal/Shader/ShaderDecodeAlu.cs

@@ -208,7 +208,11 @@ namespace Ryujinx.Graphics.Gal.Shader
             ShaderIrNode OperA = GetOperAbuf28(OpCode);
             ShaderIrNode OperB = GetOperGpr20 (OpCode);
 
-            ShaderIrOp Op = new ShaderIrOp(ShaderIrInst.Ipa, OperA, OperB);
+            ShaderIpaMode Mode = (ShaderIpaMode)((OpCode >> 54) & 3);
+
+            ShaderIrMetaIpa Meta = new ShaderIrMetaIpa(Mode);
+
+            ShaderIrOp Op = new ShaderIrOp(ShaderIrInst.Ipa, OperA, OperB, null, Meta);
 
             Block.AddNode(GetPredNode(new ShaderIrAsg(GetOperGpr0(OpCode), Op), OpCode));
         }

Ryujinx.Graphics/Gal/Shader/ShaderIpaMode.cs

@@ -0,0 +1,10 @@
+namespace Ryujinx.Graphics.Gal.Shader
+{
+    enum ShaderIpaMode
+    {
+        Pass     = 0,
+        None     = 1,
+        Constant = 2,
+        Sc       = 3
+    }
+}

Ryujinx.Graphics/Gal/Shader/ShaderIrMetaIpa.cs

@@ -0,0 +1,12 @@
+namespace Ryujinx.Graphics.Gal.Shader
+{
+    class ShaderIrMetaIpa : ShaderIrMeta
+    {
+        public ShaderIpaMode Mode { get; private set; }
+
+        public ShaderIrMetaIpa(ShaderIpaMode Mode)
+        {
+            this.Mode = Mode;
+        }
+    }
+}