+namespace
+{
+/**
+ * This struct is used to record the position of a uniform declaration
+ * within the fragment shader source code.
+ */
+struct LocationPosition
+{
+ GLint uniformLocation; ///< The location of the uniform (used as an identifier)
+ int characterPosition; ///< the position of the uniform declaration
+ LocationPosition( GLint uniformLocation, int characterPosition )
+ : uniformLocation(uniformLocation), characterPosition(characterPosition)
+ {
+ }
+};
+
+bool sortByPosition( LocationPosition a, LocationPosition b )
+{
+ return a.characterPosition < b.characterPosition;
+}
+}
+
+void Program::GetActiveSamplerUniforms()
+{
+ GLint numberOfActiveUniforms = -1;
+ GLint uniformMaxNameLength=-1;
+
+ mGlAbstraction.GetProgramiv( mProgramId, GL_ACTIVE_UNIFORMS, &numberOfActiveUniforms );
+ mGlAbstraction.GetProgramiv( mProgramId, GL_ACTIVE_UNIFORM_MAX_LENGTH, &uniformMaxNameLength );
+
+ std::vector<std::string> samplerNames;
+ char name[uniformMaxNameLength+1]; // Allow for null terminator
+ std::vector< LocationPosition > samplerUniformLocations;
+
+ {
+ int nameLength = -1;
+ int number = -1;
+ GLenum type = GL_ZERO;
+
+ for( int i=0; i<numberOfActiveUniforms; ++i )
+ {
+ mGlAbstraction.GetActiveUniform( mProgramId, (GLuint)i, uniformMaxNameLength,
+ &nameLength, &number, &type, name );
+
+ if( type == GL_SAMPLER_2D || type == GL_SAMPLER_CUBE || type == GL_SAMPLER_EXTERNAL_OES )
+ {
+ GLuint location = mGlAbstraction.GetUniformLocation( mProgramId, name );
+ samplerNames.push_back(name);
+ samplerUniformLocations.push_back(LocationPosition(location, 0u));
+ }
+ }
+ }
+
+ if( samplerUniformLocations.size() > 1 )
+ {
+ // Now, re-order according to declaration order in the fragment source.
+ std::string fragShader( mProgramData->GetFragmentShader() );
+ for( unsigned int i=0; i<samplerUniformLocations.size(); ++i )
+ {
+ // Better to write own search algorithm that searches for all of
+ // the sampler names simultaneously, ensuring only one iteration
+ // over fragShader.
+ size_t characterPosition = fragShader.find( samplerNames[i] );
+ samplerUniformLocations[i].characterPosition = characterPosition;
+ }
+ std::sort( samplerUniformLocations.begin(), samplerUniformLocations.end(), sortByPosition);
+ }
+
+ for( unsigned int i=0; i<samplerUniformLocations.size(); ++i )
+ {
+ mSamplerUniformLocations.push_back( samplerUniformLocations[i].uniformLocation );
+ }
+}
+
+bool Program::GetSamplerUniformLocation( unsigned int index, GLint& location )
+{
+ bool result = false;
+ if( index < mSamplerUniformLocations.size() )
+ {
+ location = mSamplerUniformLocations[index];
+ result = true;
+ }
+ return result;
+}
+