tree 354fba42ca64d22b3f02b66b06d5d883d903b6d2
parent 5e3c9d53d8eff5e29a05f90675f75f80a15e8ee3
author Alexis Hetu <sugoi@google.com> 1558993239 -0400
committer Alexis Hétu <sugoi@google.com> 1559327478 +0000

BuiltInPointCoord implementation

BuiltInPointCoord is defined as:

"The following formulas are used to evaluate s and t:

s = 1/2 + (xp - xf) / size
t = 1/2 + (yp - yf) / size

where size is the point’s size; (xp,yp) is the location at which the
point sprite coordinates are evaluated - this may be the framebuffer
coordinates of the fragment center, or the location of a sample; and
(xf,yf) is the exact, unrounded framebuffer coordinate of the vertex
for the point."

So it was implemented by writing (xf,yf) in SetupRoutine, where this
information is present and using the fragment's x and y coordinates
as (xp,yp), which passes the test.

Tests: dEQP-VK.glsl.builtin_var.simple.pointcoord

Change-Id: I9146349bcce0f7c31dd0464c0f210a7306d5d033
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/31992
Presubmit-Ready: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Chris Forbes <chrisforbes@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Alexis Hétu <sugoi@google.com>