Reland "Use a table for dither effect rather than math."
This is a reland of 0de475e29ec84f9ec892997565fc4f6348e4610e
Old code restored behind a build flag pending web_test rebaseline.
Original change's description:
> Use a table for dither effect rather than math.
>
> We used to use integer math on sk_FragCoord, when supported, and a
> fallback using floating point (on a 4x4 rather than 8x8 grid). Now we
> precompute a 8x8 table in a texture because it was shown to be
> significantly faster on several devices. Test was done with the following
> running in viewer with the stats layer enabled and looking at total
> frame time:
> SkRandom r;
> for (int i = 0; i < N; ++i) {
> SkColor c[2] = {r.nextU(), c[1] = r.nextU()};
> SkPoint pts[2] = {{r.nextRangeScalar(0, 500), r.nextRangeScalar(0, 500)},
> {r.nextRangeScalar(0, 500), r.nextRangeScalar(0, 500)}};
> SkPaint p;
> p.setDither(true);
> p.setShader(SkGradientShader::MakeLinear(pts, c, nullptr, 2, SkTileMode::kRepeat));
> canvas->drawPaint(p);
> }
>
> Device GPU N no dither int math dither table dither
> Linux desktop QuadroP1000 5000 304ms 400ms (1.31x) 383ms (1.26x)
> TecnoSpark3Pro PowerVRGE8320 200 299ms 820ms (2.74x) 592ms (1.98x)
> Pixel 4 Adreno640 500 110ms 221ms (2.01x) 214ms (1.95x)
> Galaxy S20 FE Mali-G77 MP11 600 165ms 360ms (2.18x) 260ms (1.58x)
>
>
> Bug: b/195281495
> Change-Id: I200a2be8e450ab66f7c8ae340a5c83ec6780db09
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/437239
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Bug: b/195281495
Change-Id: Ia52d24aa731281b161865b08954f9eeaca0033eb
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/437677
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
1 file changed