Workaround for Intel FrontFacing built-in variable bug (#2540)

2 files changed, 27 insertions, 10 deletions

diff --git a/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs b/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs
index f6aab74d..ef3b0bed 100644
--- a/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs
+++ b/Ryujinx.Graphics.Shader/CodeGen/Glsl/Instructions/InstGenMemory.cs
@@ -157,15 +157,18 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl.Instructions
 
             offsetExpr = Enclose(offsetExpr, src2, Instruction.ShiftRightS32, isLhs: true);
 
+            var config = context.Config;
+            bool indexElement = !config.GpuAccessor.QueryHostHasVectorIndexingBug();
+
             if (src1 is AstOperand oper && oper.Type == OperandType.Constant)
             {
-                bool cbIndexable = context.Config.UsedFeatures.HasFlag(Translation.FeatureFlags.CbIndexing);
-                return OperandManager.GetConstantBufferName(oper.Value, offsetExpr, context.Config.Stage, cbIndexable);
+                bool cbIndexable = config.UsedFeatures.HasFlag(Translation.FeatureFlags.CbIndexing);
+                return OperandManager.GetConstantBufferName(oper.Value, offsetExpr, config.Stage, cbIndexable, indexElement);
             }
             else
             {
                 string slotExpr = GetSoureExpr(context, src1, GetSrcVarType(operation.Inst, 0));
-                return OperandManager.GetConstantBufferName(slotExpr, offsetExpr, context.Config.Stage);
+                return OperandManager.GetConstantBufferName(slotExpr, offsetExpr, config.Stage, indexElement);
             }
         }
 
@@ -314,7 +317,7 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl.Instructions
 
             // 2D Array and Cube shadow samplers with LOD level or bias requires an extension.
             // If the extension is not supported, just remove the LOD parameter.
-            if (isArray && isShadow && (is2D || isCube) && !context.Config.GpuAccessor.QuerySupportsTextureShadowLod())
+            if (isArray && isShadow && (is2D || isCube) && !context.Config.GpuAccessor.QueryHostSupportsTextureShadowLod())
             {
                 hasLodBias = false;
                 hasLodLevel = false;
@@ -322,7 +325,7 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl.Instructions
 
             // Cube shadow samplers with LOD level requires an extension.
             // If the extension is not supported, just remove the LOD level parameter.
-            if (isShadow && isCube && !context.Config.GpuAccessor.QuerySupportsTextureShadowLod())
+            if (isShadow && isCube && !context.Config.GpuAccessor.QueryHostSupportsTextureShadowLod())
             {
                 hasLodLevel = false;
             }
diff --git a/Ryujinx.Graphics.Shader/CodeGen/Glsl/OperandManager.cs b/Ryujinx.Graphics.Shader/CodeGen/Glsl/OperandManager.cs
index 03fbb8a4..60a471eb 100644
--- a/Ryujinx.Graphics.Shader/CodeGen/Glsl/OperandManager.cs
+++ b/Ryujinx.Graphics.Shader/CodeGen/Glsl/OperandManager.cs
@@ -117,8 +117,13 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl
             return $"{GetUbName(stage, slot, cbIndexable)}[{offset >> 2}].{GetSwizzleMask(offset & 3)}";
         }
 
-        private static string GetVec4Indexed(string vectorName, string indexExpr)
+        private static string GetVec4Indexed(string vectorName, string indexExpr, bool indexElement)
         {
+            if (indexElement)
+            {
+                return $"{vectorName}[{indexExpr}]";
+            }
+
             string result = $"{vectorName}.x";
             for (int i = 1; i < 4; i++)
             {
@@ -127,14 +132,14 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl
             return $"({result})";
         }
 
-        public static string GetConstantBufferName(int slot, string offsetExpr, ShaderStage stage, bool cbIndexable)
+        public static string GetConstantBufferName(int slot, string offsetExpr, ShaderStage stage, bool cbIndexable, bool indexElement)
         {
-            return GetVec4Indexed(GetUbName(stage, slot, cbIndexable) + $"[{offsetExpr} >> 2]", offsetExpr + " & 3");
+            return GetVec4Indexed(GetUbName(stage, slot, cbIndexable) + $"[{offsetExpr} >> 2]", offsetExpr + " & 3", indexElement);
         }
 
-        public static string GetConstantBufferName(string slotExpr, string offsetExpr, ShaderStage stage)
+        public static string GetConstantBufferName(string slotExpr, string offsetExpr, ShaderStage stage, bool indexElement)
         {
-            return GetVec4Indexed(GetUbName(stage, slotExpr) + $"[{offsetExpr} >> 2]", offsetExpr + " & 3");
+            return GetVec4Indexed(GetUbName(stage, slotExpr) + $"[{offsetExpr} >> 2]", offsetExpr + " & 3", indexElement);
         }
 
         public static string GetOutAttributeName(AstOperand attr, ShaderConfig config)
@@ -198,6 +203,15 @@ namespace Ryujinx.Graphics.Shader.CodeGen.Glsl
                             case AttributeConsts.PositionY: return $"(gl_FragCoord.y / {DefaultNames.SupportBlockRenderScaleName}[0])";
                             case AttributeConsts.PositionZ: return "gl_FragCoord.z";
                             case AttributeConsts.PositionW: return "gl_FragCoord.w";
+
+                            case AttributeConsts.FrontFacing:
+                                if (config.GpuAccessor.QueryHostHasFrontFacingBug())
+                                {
+                                    // This is required for Intel on Windows, gl_FrontFacing sometimes returns incorrect
+                                    // (flipped) values. Doing this seems to fix it.
+                                    return "(-floatBitsToInt(float(gl_FrontFacing)) < 0)";
+                                }
+                                break;
                         }
                     }