I have a very strange problem with my latest screensaver.
Everything renders perfectly in QC... but when I view it as a screensaver, one of the images (which forms the gas cloud from the exploding star) has lots of artifacts in its alpha channel. In other words, the coloring is correct, but the alpha has tiny little rectangles cut out of it. This only happens in the screensaver (both preview and full screen) and never in QC.
What could be causing this?
In Quartz Composer, when rendering the same composition, go into the Viewer menu and disable background erasing. The rendering will then be the same as in any application. If you observe the same artifacts, then it means the color buffer or depth buffer is not cleared completely:
Add a Clear patch to the composition and change its settings in the Inspector accordingly.
