20150521 - Natalya Tatarchuk: Applied Graphics Research for Video Games

Lots of great stuff in Natalya Tatarchuk: Applied Graphics Research for Video Games including the "Case Study: Low Res Transparency - Improved Method".

General idea without optimizations, render full resolution then down-sample depth to 1/4 x 1/4 resolution grabbing minimum and maximum. Blend soft particles to both minimum and maximum. During up-sample, each group of 4x4 pixels could possibly source from 4 minimum and 4 maximum samples (weighted average of 8 values).

The same method can be applied to solve transparency and MSAA blending, by blending in transparency during a custom MSAA resolve. With GCN's layered MSAA layout it might even be possible to remove the down-sampling pre-pass. Could grab minimum and maximum from from just the first MSAA layer. That may miss some thin sub-pixel geometry in-front of the first MSAA layer. In the compute custom MSAA resolve could image store if a 4x4 pixel tile misses thin sub-pixel geometry. Then use back-projection to use that flag in the next frame to force a full check.