From 7b39107e3ae056a857e1780b2123e757b8deab26 Mon Sep 17 00:00:00 2001
From: FernandoS27 <fsahmkow27@gmail.com>
Date: Wed, 10 Oct 2018 09:20:13 -0400
Subject: [PATCH] Added Alpha Func

---
 .../renderer_opengl/gl_rasterizer.cpp         | 10 +++++-
 .../renderer_opengl/gl_shader_decompiler.cpp  | 36 +++++++++++++++++--
 2 files changed, 43 insertions(+), 3 deletions(-)

diff --git a/src/video_core/renderer_opengl/gl_rasterizer.cpp b/src/video_core/renderer_opengl/gl_rasterizer.cpp
index e2a422052..17860d447 100644
--- a/src/video_core/renderer_opengl/gl_rasterizer.cpp
+++ b/src/video_core/renderer_opengl/gl_rasterizer.cpp
@@ -885,10 +885,18 @@ u32 RasterizerOpenGL::SetupTextures(Maxwell::ShaderStage stage, Shader& shader,
 void RasterizerOpenGL::SetupAlphaTesting(Shader& shader) {
     const auto& regs = Core::System::GetInstance().GPU().Maxwell3D().regs;
 
-    glProgramUniform1i(shader->GetProgramHandle(), shader->GetAlphaTestingEnableLocation(),
+    glProgramUniform1ui(shader->GetProgramHandle(), shader->GetAlphaTestingEnableLocation(),
                        regs.alpha_test_enabled);
     glProgramUniform1f(shader->GetProgramHandle(), shader->GetAlphaTestingRefLocation(),
                        regs.alpha_test_ref);
+
+    u32 func = static_cast<u32>(regs.alpha_test_func);
+    // Normalize the gl variants of opCompare to be the same as the normal variants
+    if (func >= 0x200) {
+        func = func - 0x200 + 1U;
+    }
+
+    glProgramUniform1ui(shader->GetProgramHandle(), shader->GetAlphaTestingFuncLocation(), func);
 }
 
 void RasterizerOpenGL::SyncViewport() {
diff --git a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
index e890cfe57..cbf501cc7 100644
--- a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
+++ b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
@@ -1280,13 +1280,13 @@ private:
                 header.ps.IsColorComponentOutputEnabled(render_target, 1) ||
                 header.ps.IsColorComponentOutputEnabled(render_target, 2) ||
                 header.ps.IsColorComponentOutputEnabled(render_target, 3)) {
-                shader.AddLine(fmt::format("if ({} < alpha_testing_ref) discard;",
+                shader.AddLine(fmt::format("if (AlphaFunc({}, alpha_testing_ref, alpha_testing_func)) discard;",
                                            regs.GetRegisterAsFloat(current_reg)));
                 current_reg += 4;
             }
         }
         --shader.scope;
-        shader.AddLine("}");
+        shader.AddLine('}');
 
         // Write the color outputs using the data in the shader registers, disabled
         // rendertargets/components are skipped in the register assignment.
@@ -3505,6 +3505,38 @@ private:
             declarations.AddLine("bool " + pred + " = false;");
         }
         declarations.AddNewLine();
+        GenerateFunctionDeclarations();
+    }
+
+    void GenerateFunctionDeclarations() {
+        if (stage == Maxwell3D::Regs::ShaderStage::Fragment) {
+            declarations.AddLine("bool AlphaFunc(in float value, in float ref, in uint func) {");
+            declarations.scope++;
+            declarations.AddLine("switch (func) {");
+            declarations.scope++;
+            declarations.AddLine("case 1:");
+            declarations.AddLine("return false;");
+            declarations.AddLine("case 2:");
+            declarations.AddLine("return value < ref;");
+            declarations.AddLine("case 3:");
+            declarations.AddLine("return value == ref;");
+            declarations.AddLine("case 4:");
+            declarations.AddLine("return value <= ref;");
+            declarations.AddLine("case 5:");
+            declarations.AddLine("return value > ref;");
+            declarations.AddLine("case 6:");
+            declarations.AddLine("return value != ref;");
+            declarations.AddLine("case 7:");
+            declarations.AddLine("return value >= ref;");
+            declarations.AddLine("case 8:");
+            declarations.AddLine("return true;");
+            declarations.AddLine("default:");
+            declarations.AddLine("return false;");
+            declarations.scope--;
+            declarations.AddLine('}');
+            declarations.scope--;
+            declarations.AddLine('}');
+        }
     }
 
 private: