I am doing a project in which a rocket ship flies over an alien world with a lake filled with lava. The ship also has smoke coming out the back.
I have done divided my scene into four render layers; one for the rocket, one for the lava, one for the smoke, and one for the background. All other necessary compositing operations have been carried out. I have made the lava glow, the smoke look like smoke, and the rocket look blurred. All I need to do now is combine these layers together into a finished output. This is where the trouble started. I was able to combine the rocket and the background alright, but when I try to combine the lava with the background or the smoke with the background, nothing happens. I have tried the Alpha Over node, the Z Combine node, and even the Add node, all with no result. What could I be doing wrong?