background(0,0,0,0) seems to clear screen

Might be by design, but was unexpected. In my defense I was only doing it to try and fix the weird residual artifacts I’m seeing during my non-screen-clearing rendering. :wink:

Yes, alpha in the background call doesn’t do anything. This is because it is simply a synonym for OpenGL’s glClear(r, g, b, a) function. The alpha in a glClear doesn’t perform a composite on existing screen pixels, it overwrites them with the value.