Implement GetFragDataLocation, often used by applications with MRT shaders in GLSL ES version 300.

src/libGLESv2/ProgramBinary.cpp

@@ -372,6 +372,25 @@ UniformBlock *ProgramBinary::getUniformBlockByIndex(GLuint blockIndex)
     return mUniformBlocks[blockIndex];
 }
 
+GLint ProgramBinary::getFragDataLocation(const char *name) const
+{
+    std::string baseName(name);
+    unsigned int arrayIndex;
+    arrayIndex = parseAndStripArrayIndex(&baseName);
+
+    for (auto locationIt = mOutputVariables.begin(); locationIt != mOutputVariables.end(); locationIt++)
+    {
+        const VariableLocation &outputVariable = locationIt->second;
+
+        if (outputVariable.name == baseName && (arrayIndex == GL_INVALID_INDEX || arrayIndex == outputVariable.element))
+        {
+            return static_cast<GLint>(locationIt->first);
+        }
+    }
+
+    return -1;
+}
+
 template <typename T>
 bool ProgramBinary::setUniform(GLint location, GLsizei count, const T* v, GLenum targetUniformType)
 {

src/libGLESv2/ProgramBinary.h

@@ -132,6 +132,8 @@ class ProgramBinary : public RefCountObject
     GLuint getActiveUniformBlockMaxLength() const;
     UniformBlock *getUniformBlockByIndex(GLuint blockIndex);
 
+    GLint getFragDataLocation(const char *name) const;
+
     void validate(InfoLog &infoLog);
     bool validateSamplers(InfoLog *infoLog);
     bool isValidated() const;

src/libGLESv2/libGLESv2.cpp

@@ -9804,10 +9804,28 @@ GLint __stdcall glGetFragDataLocation(GLuint program, const GLchar *name)
         {
             if (context->getClientVersion() < 3)
             {
-                return gl::error(GL_INVALID_OPERATION, 0);
+                return gl::error(GL_INVALID_OPERATION, -1);
             }
 
-            UNIMPLEMENTED();
+            if (program == 0)
+            {
+                return gl::error(GL_INVALID_VALUE, -1);
+            }
+
+            gl::Program *programObject = context->getProgram(program);
+
+            if (!programObject || !programObject->isLinked())
+            {
+                return gl::error(GL_INVALID_OPERATION, -1);
+            }
+
+            gl::ProgramBinary *programBinary = programObject->getProgramBinary();
+            if (!programBinary)
+            {
+                return gl::error(GL_INVALID_OPERATION, -1);
+            }
+
+            return programBinary->getFragDataLocation(name);
         }
     }
     catch(std::bad_alloc&)