commit f4238ec8ad0e9b0995142dc3b0b9a18de167ae3f
author Pyry Haulos <phaulos@google.com> Tue Feb 24 15:42:31 2015 -0800
committer Pyry Haulos <phaulos@google.com> Tue Feb 24 15:42:31 2015 -0800
tree d47fde1bfcf4f5f5eddb129025e2a036eb8cfd5f
parent 0a3b01c9060322986341f27c8bf0e6261a7d4049

Improve depth interpolation in reference renderer

This change reformulates depth value interpolation to exactly preserve
constant depth across a triangle. Old interpolation code exhibited
serious Z-fighting with two (Z-)overlapping screen-aligned triangles.

In addition barycentric precision is slightly improved by actually
dividing with the sum instead of sharing pre-computed 1/sum.

A simple test for constant depth and varying interpolation is provided.

Change-Id: If6229f9652bcf3dbe1d273ed8e131b175c06dfc2