bool PreprocessShader ( [FShaderPreprocessOutput](API\Runtime\RenderCore\FShaderPreprocessOutput) & Output, const [FShaderCompilerInput](API\Runtime\RenderCore\FShaderCompilerInput) & Input, const [FShaderCompilerEnvironment](API\Runtime\RenderCore\FShaderCompilerEnvironment) & MergedEnvironment, const [FShaderCompilerDefinitions](API\Runtime\RenderCore\FShaderCompilerDefinitions) & AdditionalDefines, [EDumpShaderDefines](API\Developer\ShaderPreprocessor\EDumpShaderDefines) DefinesPolicy )