[Bf-committers] transparent zbuffer optimizations break OSA

[joe]

Hi.  I've noticed that the transparent zbuffer optimization of
combining subpixel samples that have the same face break OSA.  This
seems to be because when comparing if two subpixel samples should be
merged it doesn't check the two depths.  I've tried adding this
myself, where if the difference in depth is greater then a max value
the two samples arn't merged.  However, I haven't had much success,
and it turns out figuring out the max value is much more complicated
then I initially thought, a simple constant might theoretically cause
render errors at difference scene scales :/ .

Since deep shadow maps cannot affort this problem, the optimization is
turned off for them.

Joe