void initDeferred(){

        batch = new Batch;
        batch.begin(4, GL_TRIANGLE_FAN);
        batch.add([-1, 1, 0]);
        batch.add([-1, -1, 0]);
        batch.add([1, -1, 0]);
        batch.add([1, 1, 0]);
        batch.finish();

        width = 512;
        height = 512;
        gbuffer = new GBuffer(width, height);
        string vertex = "
            #version 330
            in vec4 vertex;
            void main(){
                gl_Position = vertex;
            }
        ";
        string fragment = "
            #version 330
            out vec3 outDiffuse;
            void main(){
                outDiffuse = vec3(1,1,1);
            }
        ";
        geomPassShader = Shader.prepare("gbuffer_forwarder");
        geomPassShader.start("gbuffer_forwarder", vertex, fragment);
        geomPassShader.addAttribute(gl.attributeVertex, "vertex");
        geomPassShader.bindFragOut(GBuffer.DIFFUSE, "outDiffuse");
        geomPassShader.finish;
    }

    void geomPass(){
        gbuffer.bindWrite;
        glViewport(0,0,width,height);
        float[3] green = [0, 1, 0];
        float one = 1;
        glClearBufferfv(GL_COLOR, 0, green.ptr);
        glClearBufferfv(GL_DEPTH, 0, &one);
        geomPassShader.use;
        batch.draw;
    }

    void lightPass(){
        glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
        gbuffer.bindRead();
        gbuffer.setRead(GBuffer.DIFFUSE);
        glBlitFramebuffer(0, 0, width, height, 0, 0, width, height, GL_COLOR_BUFFER_BIT, GL_NEAREST);
    }