Blender Git Loki

Fix T43865: Cycles: Watertight rendering produces artifacts on a huge plane

The issue was caused by numerical instability whrn having ray origin close to a huge
triangle, which could have aused bad ray distance check.

Watertight Woop intersection isn't really addressing such cases, it's dealing with
small triangles far away from the ray origin instead, so it's a bit tricky yo make
it working reliably.

While we're quite close to the release it's safer to do check in Pleaucker coordinates
if ray close to a huge triangle. Likely this additional check combined with some other
tweaks to the code doesn't cause measurable slowdown in the scenes tested here.

After the release we can play a bit more with this code in order to make it more
stable without Pleucker fallback.