[_bxg1]

I just did it across the board; since the error is in the floating-point noise I don't know if I'd even trust a comparison on that. Plus, the discrepancy between "bumped" and "unbumped" samples might cause some visible artifacts.

[cellular]

Direct3D used to have a Z-bias for a similar problem: rendering pictures hanging on walls at a far Z depth. Their whql tests even tested for it.

It was fun discovering all the corner cases while debugging drivers.