They were an interesting idea and might be useful in the future, but
they don't work as well as I had hoped for quake's maps due to the
overlapping light volumes causing contention while doing the additive
blends in the frame buffer. The cause was made obvious when testing in
the marcher map: most of its over 400 lights have infinite radius thus
require full screen passes: all those passes fighting for the frame
buffer did very nasty things to performance. However, light splats might be
useful for many small, non-overlapping light volumes, thus the code is
being kept (and I like the cleanups that came with it).
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