LumixEngine

Custom postprocess

1. Create a new class, which inherits from RenderPlugin.

2. Implement needed methods in your class. Implement necessary shaders. Here is an example for a film grain postprocess:

    struct FilmGrain : public RenderPlugin {
        Renderer& m_renderer;
        Shader* m_shader = nullptr;
        float m_noise_scale = 2.f;
   
        FilmGrain(Renderer& renderer) : m_renderer(renderer) {}
   
        void shutdown() {
            m_shader->decRefCount();
        }
   
        void init() {
            ResourceManagerHub& rm = m_renderer.getEngine().getResourceManager();
            m_shader = rm.load<Shader>(Path("shaders/film_grain.hlsl"));
        }
   
        RenderBufferHandle renderAfterTonemap(const GBuffer& gbuffer, RenderBufferHandle input, Pipeline& pipeline) override {
            if (!m_shader->isReady()) return input;
            if (pipeline.getType() != PipelineType::GAME_VIEW) return input;
   
            RenderModule* module = pipeline.getModule();
            EntityPtr camera_entity = module->getActiveCamera();
            if (!camera_entity.isValid()) return input;
   
            Camera& camera = module->getCamera(*camera_entity);
            if (camera.film_grain_intensity <= 1e-5) return input;
   
            pipeline.beginBlock("film_grain");
   
            DrawStream& stream = pipeline.getRenderer().getDrawStream();
            const Viewport& vp = pipeline.getViewport();
            struct {
                float intensity;
                float lumamount;
                gpu::RWBindlessHandle source;
            } ubdata = {
                camera.film_grain_intensity,
                0.1f,
                pipeline.toRWBindless(input, stream),
            };
            pipeline.setUniform(ubdata);
            pipeline.dispatch(*m_shader, (vp.w + 15) / 16, (vp.h + 15) / 16, 1);
   
            pipeline.endBlock();
            return input;
        }
    };
   

3. Create an instance of your class. Let’s call it my_postprocess.

4. Add your postprocess to a renderer using addPlugin.

    Renderer& renderer = ...;
    renderer.addPlugin(my_postprocess);
   

   Your postprocess should just work now.

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