Set up two framebuffer objects (refer to the Rendering to a texture recipe in Chapter 5, Using Textures), and two corresponding textures. The first FBO should have a depth buffer because it will be used for the first pass. The second FBO need not have a depth buffer because, in the second and third passes, we'll only render a single screen-filling quad in order to execute the fragment shader once for each pixel.
As with the previous recipe, we'll use a uniform variable to select the functionality of each pass. The OpenGL program should also set the following uniform variables:
- Width: This is used to set the width of the screen in pixels
- Height: This is used to set the height of the screen in pixels
- Weight[]: This is the array ...
