tree cf05e8d76065e82b32ac76b33ea9a324dcd97932
parent 0bbf7ba9f909092f0328b1d519d5f7db1773be57
author Nicolas Capens <capn@google.com> 1580155094 -0500
committer Nicolas Capens <nicolascapens@google.com> 1582036176 +0000

Fix sRGB conversion precision issues

When sampling an sRGB texture format, we have a vector of 16-bit
elements where 0xFF00 represents 1.0, but we were using a lookup table
which produced results in a 0xFFFF base.

Also on linear to sRGB conversion, precision was lost due to truncating
to 12-bit. Adding a rounding factor before truncating preserves
precision.

Bug: b/149574741
Change-Id: I19218c958867c4b5e97dc3b62b4ea83f37161134
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/41268
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>