tree d7ace95952d47dc5c3840b835d3d016c2b79d5a6
parent 010a464878f32daed863edee3fc6ad21920d605b
author Nicolas Capens <capn@google.com> 1499445981 -0400
committer Nicolas Capens <nicolascapens@google.com> 1500560765 +0000

Improve mipmap LOD calculation precision.

Our approximation for log2() linearly interpolates between powers of
two. This is not accurate enough for some use cases. Squaring the input
effectively doubles the number of piecewise linear segments.

Bug swiftshader:71

Change-Id: Ie7a1da6b93cb5fbed018b61cf8510393964b5aa4
Reviewed-on: https://swiftshader-review.googlesource.com/10450
Reviewed-by: Alexis Hétu <sugoi@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>