function update () {

    // Draw Shadows
    if (shadows) {
        gl.disable(gl.DEPTH_TEST);

        bindShadowFBO()

        shadowShaderON();
        drawWorld(); // from light point of view

        shadowShaderOFF();
        unbindShadowFBO()
    }

    // Bind Post Processor FBO IN
    if (postProcessing) { PostProcessor.fbo.in.bind() }

    // Clear Scene
    gl.enable(gl.DEPTH_TEST);
    gl.clear(gl.COLOR_BUFFER_BIT || gl.DEPTH_BUFFER_BIT);

    // Draw Scene
    phongShaderON();
    drawWorld();
    phongShaderOFF();


    if (postProcessing) {
         // Turn Off Post Processor FBO IN
        gl.bindFramebuffer(gl.FRAMEBUFFER, null);

        // Blit FBO IN and OUT
        gl.bindFramebuffer(gl.READ_FRAMEBUFFER, fbo.in);
        gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, fbo.out);

        gl.blitFramebuffer(
            0, 0, width, height,
            0, 0, width, height,
            gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT,
            gl.NEAREST
        );

        // Unbind READ and Draw Frame Buffers
        gl.bindFramebuffer(gl.READ_FRAMEBUFFER, null);
        gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, null);


        // Ready to draw on QUAD

        gl.disable(gl.DEPTH_TEST);

        // Process Effects
        postprocessorShaderON();
        renderQuad.bind();

        gl.activeTexture(gl.TEXTURE0);
        gl.uniform1i(location, 0);
        PostProcessor.texture.bind();

        this.quad.draw();

        PostProcessor.texture.unbind();
        postprocessorShaderOFF();

        renderQuad.unbind();
    }
}