tree 1a5be1eb07443781a0148ba29319040b8c99466f
parent 6372aceba9f8b6f2931aaab6746b3f80463edb30
author Nicolas Capens <capn@google.com> 1511536222 -0500
committer Nicolas Capens <nicolascapens@google.com> 1512142453 +0000

Compute implicit derivatives relative to first quad pixel.

Previously the derivatives in y were computed using the difference
between the second and fourth pixel in the quad. For consistency with
the x derivative, use the first and third pixel instead. Also, some
shuffling can be eliminated by having the x derivative in the y
component, and the y derivative in the z component.

Change-Id: I985dcd3c5e2c47c10caf020cf5cb79587b3b3aab
Reviewed-on: https://swiftshader-review.googlesource.com/14168
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>