[Fix] (MG_Impl/GLImpl, MG_State/GLState): fix frag data location queries [skip ci]

MobileGL/MG_Impl/GLImpl/Program/GL_Program.cpp

@@ -1200,6 +1200,19 @@ namespace MobileGL::MG_Impl::GLImpl {
                                              std::to_string(program) + " is not the name of a program object."));
             return -1;
         }
+        if (name == nullptr) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidValue,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__, "name cannot be null."));
+            return -1;
+        }
+        if (!programObject->GetLinkStatus()) {
+            MG_State::pGLContext->RecordError(
+                ErrorCode::InvalidOperation,
+                MakeUnique<GenericErrorInfo>("MG_Impl/GLImpl", __func__,
+                                             std::to_string(program) + " has not been linked successfully."));
+            return -1;
+        }
         return programObject->GetFragmentDataLocation(name);
     }
 

MobileGL/MG_State/GLState/ProgramState/ProgramObject.cpp

@@ -214,6 +214,7 @@ namespace MobileGL::MG_State::GLState {
         if (result) {
             m_linkStatus = true;
             m_program = result.value();
+            m_linkedFragDataLocation = m_explicitFragDataLocation;
             MGLOG_D("ProgramObject %u: LinkProgram succeeded, TProgram ptr %p", m_externalIndex, m_program.get());
         } else {
             m_infoLog = result.error().log;
@@ -592,12 +593,12 @@ namespace MobileGL::MG_State::GLState {
     Int ProgramObject::GetFragmentDataLocation(const char* name) {
         if (!m_program || !name) return -1;
 
-        const auto explicitLocation = m_explicitFragDataLocation.find(name);
+        const auto explicitLocation = m_linkedFragDataLocation.find(name);
         const Int outputCount = m_program->getNumPipeOutputs();
         for (Int index = 0; index < outputCount; ++index) {
             const auto& output = m_program->getPipeOutput(index);
             if (output.name != name) continue;
-            if (explicitLocation != m_explicitFragDataLocation.end()) return static_cast<Int>(explicitLocation->second);
+            if (explicitLocation != m_linkedFragDataLocation.end()) return static_cast<Int>(explicitLocation->second);
             return static_cast<Int>(output.layoutLocation());
         }
         return -1;

MobileGL/MG_State/GLState/ProgramState/ProgramObject.h

@@ -257,6 +257,7 @@ namespace MobileGL::MG_State::GLState {
 
         // FragData (Frag out)
         UnorderedMap<String, Uint> m_explicitFragDataLocation;
+        UnorderedMap<String, Uint> m_linkedFragDataLocation;
 
         // Uniforms
         UnorderedMap<String, Uint> m_uniformLocations;

MobileGL/MG_Test/Program/ProgramUtilTest.cpp

@@ -142,6 +142,30 @@ void main() {
     EXPECT_EQ(source.find("#define"), String::npos);
 }
 
+TEST_F(ProgramUtilTest, PreprocessLegacyFragmentShaderModernizesFragData) {
+    using namespace MG_Util::ShaderTranspiler;
+
+    String source = R"(#version 130
+void main() {
+    gl_FragData[0] = vec4(1.0);
+    gl_FragData[1].a = 0.5;
+})";
+
+    PreprocessShaderSource(ShaderStage::Fragment, source);
+
+    EXPECT_EQ(source.find("#version 460 core\n"), 0);
+    EXPECT_NE(source.find("layout(location = 0) out vec4 mg_FragData[8];\n"), String::npos);
+    EXPECT_NE(source.find("mg_FragData[0] = vec4(1.0);"), String::npos);
+    EXPECT_NE(source.find("mg_FragData[1].a = 0.5;"), String::npos);
+    EXPECT_EQ(source.find("gl_FragData"), String::npos);
+
+    ShaderAttrib attrib{.shaderType = GL_FRAGMENT_SHADER, .sourceStr = source};
+    auto res = ShaderCompiler::CompileShader(attrib);
+    if (!res) {
+        FAIL() << "errc: " << res.error().errc << "\nlog: " << res.error().log << "\nsource:\n" << source;
+    }
+}
+
 TEST_F(ProgramUtilTest, PreprocessFragmentShaderInjectsDepthRangeShim) {
     using namespace MG_Util::ShaderTranspiler;
 

MobileGL/MG_Util/ShaderTranspiler/ShaderSourceProcessor.cpp

@@ -286,10 +286,15 @@ namespace {
         if (stage == MobileGL::ShaderStage::Fragment) {
             ReplaceIdentifier(source, "varying", "in");
             const bool usesFragColor = source.find("gl_FragColor") != MobileGL::String::npos;
+            const bool usesFragData = source.find("gl_FragData") != MobileGL::String::npos;
             if (usesFragColor) {
                 ReplaceIdentifier(source, "gl_FragColor", "mg_FragColor");
                 source.insert(FindAfterVersionDirective(source), "out vec4 mg_FragColor;\n");
             }
+            if (usesFragData) {
+                ReplaceIdentifier(source, "gl_FragData", "mg_FragData");
+                source.insert(FindAfterVersionDirective(source), "layout(location = 0) out vec4 mg_FragData[8];\n");
+            }
         }
     }