As mentioned previously, we've skipped anything that deals with opaque geometry. In general, one would probably want to render any opaque geometry first, with the depth buffer enabled, and store the rendered fragments in a texture. Then, when rendering the transparent geometry, one would disable writing to the depth buffer, and build the linked list as shown previously. Finally, you could use the value of the opaque texture as the background color when blending the linked lists.
This is the first example in this book that makes use of reading and writing from/to arbitrary (shared) storage from a shader. This capability, has given us much more flexibility, but that comes at a price. As indicated previously, we have to be very ...
