skia2/resources/sksl/intrinsics/RoundEven.sksl
John Stiles 368166262a Add trunc/round/roundEven SKSL ES3 public APIs.
Improved tests caught a longstanding bug in the compile-time
optimization logic for round/roundEven. These would *always* round to an
even number even when it didn't make sense to do so. (e.g. 3.1 would
round to 4.)

RoundEven isn't available in lower shader models of Direct3D;
SPIRV-Cross throws if it's unavailable. We may need a caps bit for this.

Change-Id: I3cc50238a2116b8d4e2c4059730d8b5cfb2bb056
Bug: skia:12022, skia:12352
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/441078
Auto-Submit: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
2021-08-23 15:44:15 +00:00

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uniform half4 testInputs; // -1.25, 0, 0.75, 2.25
uniform half4 colorGreen, colorRed;
half4 main(float2 coords) {
const float4 expectedA = half4(-1.0, 0.0, 1.0, 2.0);
const float4 constVal = half4(-6.75, -0.475, 3.5, 2.5);
const float4 expectedB = half4(-7.0, -0.0, 4.0, 2.0);
return (roundEven(testInputs.x) == expectedA.x &&
roundEven(testInputs.xy) == expectedA.xy &&
roundEven(testInputs.xyz) == expectedA.xyz &&
roundEven(testInputs.xyzw) == expectedA.xyzw &&
roundEven(constVal.x) == expectedB.x &&
roundEven(constVal.xy) == expectedB.xy &&
roundEven(constVal.xyz) == expectedB.xyz &&
roundEven(constVal.xyzw) == expectedB.xyzw) ? colorGreen : colorRed;
}