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Reland "Fix issues with insetting and outsetting quads."

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This is a reland of 4a281dc8ee

Original change's description:
> Fix issues with insetting and outsetting quads.
>
> Need more degrees of freedom when moving 3D points to project to 2D
> points that don't fall on the projected quad edges.
>
> Need to check geometry subset in shader to avoid positive coverage in
> outset quads with nearly parallel edges.
>
> Bug: chromium:1177833
> Change-Id: I0759382d9221ba44aacd537254e08d9f2716a6af
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/372196
> Reviewed-by: Michael Ludwig <michaelludwig@google.com>
> Commit-Queue: Brian Salomon <bsalomon@google.com>

Bug: chromium:1177833
Change-Id: Icf2b11334489c12f30e792526093c0d4bbaca5e0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/375058
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
This commit is contained in:
Brian Salomon 2021-02-24 10:09:02 -05:00
parent 31ece716be
commit 659e71f474
4 changed files with 132 additions and 4 deletions
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98
gm/crbug_1177833.cpp Normal file
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@ -0,0 +1,98 @@
/*
* Copyright 2021 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "gm/gm.h"
#include "include/core/SkCanvas.h"
#include "include/core/SkMatrix.h"
#include "include/core/SkRect.h"
// Bad quads dumped from SkiaRenderer in crbug.com/1178833. These should all draw as really thin
// lines.
DEF_SIMPLE_GM(crbug_1177833, canvas, 400, 400) {
canvas->clear(SK_ColorBLACK);
canvas->translate(-700, -700);
// This quad had two issues. The inset collapsed the inner 2D projected quad to a point but
// didn't enable enough degrees of freedom to adjust the 4 3D points to project to that point.
// Also, the outset produced a 2D projected point far away from the original quad but the
// shader was not checking the geometric subset and so pixels far away from the projection of
// the quad would have positive coverage.
{
canvas->save();
canvas->concat(SkMatrix::MakeAll(SkBits2Float(0xbf79250e), SkBits2Float(0x3e9da860), SkBits2Float(0x44914c8a),
SkBits2Float(0xbf982962), SkBits2Float(0xbf280002), SkBits2Float(0x44c3116e),
SkBits2Float(0xba9bfe62), SkBits2Float(0x39d10455), SkBits2Float(0x3fc9b377)));
SkRect rect = {SkBits2Float(0x00000000),
SkBits2Float(0x00000000),
SkBits2Float(0x40a00000),
SkBits2Float(0x43560000)};
SkPoint clip[4] = {{SkBits2Float(0x409fff57), SkBits2Float(0x40c86a18)},
{SkBits2Float(0x409fff57), SkBits2Float(0x4314dc8c)},
{SkBits2Float(0x407f6b0d), SkBits2Float(0x43157fff)},
{SkBits2Float(0x4040859c), SkBits2Float(0x43140374)}};
SkCanvas::QuadAAFlags aaFlags = static_cast<SkCanvas::QuadAAFlags>(0x00000002);
SkColor4f color = {SkBits2Float(0x3f6eeef0),
SkBits2Float(0x3f6eeef0),
SkBits2Float(0x3f6eeef0),
SkBits2Float(0x3f800000)};
SkBlendMode mode = static_cast<SkBlendMode>(0x00000003);
canvas->experimental_DrawEdgeAAQuad(rect, clip, aaFlags, color, mode);
canvas->restore();
}
// This quad also exposed the inset collapse to a point without enough degrees of freedom issue.
canvas->save();
canvas->translate(-300, 0);
{
canvas->save();
canvas->concat(SkMatrix::MakeAll(SkBits2Float(0x3f54dd8a), SkBits2Float(0xbf9096a4), SkBits2Float(0x447eae34),
SkBits2Float(0x3f3f6905), SkBits2Float(0xbe5208ba), SkBits2Float(0x4418118b),
SkBits2Float(0x3aa134a1), SkBits2Float(0xb93ef249), SkBits2Float(0x3f580bd4)));
SkRect rect = {SkBits2Float(0x00000000),
SkBits2Float(0x00000000),
SkBits2Float(0x40a00000),
SkBits2Float(0x43560000)};
SkPoint clip[4] = {{SkBits2Float(0x40a0000e), SkBits2Float(0x40c86b5a)},
{SkBits2Float(0x40a0001e), SkBits2Float(0x4314dd5f)},
{SkBits2Float(0x407f76eb), SkBits2Float(0x431580c2)},
{SkBits2Float(0x404092e7), SkBits2Float(0x43140445)}};
SkCanvas::QuadAAFlags aaFlags = static_cast<SkCanvas::QuadAAFlags>(0x00000002);
SkColor4f color = {SkBits2Float(0x3f6eeef0),
SkBits2Float(0x3f6eeef0),
SkBits2Float(0x3f6eeef0),
SkBits2Float(0x3f800000)};
SkBlendMode mode = static_cast<SkBlendMode>(0x00000003);
canvas->experimental_DrawEdgeAAQuad(rect, clip, aaFlags, color, mode);
canvas->restore();
}
canvas->restore();
// This quad exposed a similar issue to the point issue above, but when collapsing to a
// triangle. When a 2D quad edge collapsed from insetting we'd replace it with a point off of
// its adjacent edges. We need to ensure the code that moves the 3D point that projects to
// the 2D point has 2 degrees of freedom so it can find the correct 3D point.
{
canvas->save();
canvas->concat(SkMatrix::MakeAll(SkBits2Float(0x3f54b255), SkBits2Float(0x3eb5a94d), SkBits2Float(0x443d7419),
SkBits2Float(0x3f885d66), SkBits2Float(0x3f5a6b9c), SkBits2Float(0x443c7334),
SkBits2Float(0x3aa95ea5), SkBits2Float(0xb8a1391e), SkBits2Float(0x3f84dde5)));
SkRect rect = {SkBits2Float(0x00000000),
SkBits2Float(0x00000000),
SkBits2Float(0x40a00000),
SkBits2Float(0x43100000)};
SkPoint clip[4] = {{SkBits2Float(0x405a654c), SkBits2Float(0x42e8c790)},
{SkBits2Float(0x3728c61b), SkBits2Float(0x42e7df31)},
{SkBits2Float(0xb678ecc5), SkBits2Float(0x412db4e0)},
{SkBits2Float(0x4024b2ad), SkBits2Float(0x413ab3ed)}};
SkCanvas::QuadAAFlags aaFlags = static_cast<SkCanvas::QuadAAFlags>(0x00000004);
SkColor4f color = {SkBits2Float(0x3f800000),
SkBits2Float(0x3f800000),
SkBits2Float(0x3f800000),
SkBits2Float(0x3f800000)};
SkBlendMode mode = static_cast<SkBlendMode>(0x00000003);
canvas->experimental_DrawEdgeAAQuad(rect, clip, aaFlags, color, mode);
canvas->restore();
}
}

1
gn/gm.gni
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@ -118,6 +118,7 @@ gm_sources = [
"$_gm/crbug_1162942.cpp",
"$_gm/crbug_1167277.cpp",
"$_gm/crbug_1174186.cpp",
"$_gm/crbug_1177833.cpp",
"$_gm/crbug_224618.cpp",
"$_gm/crbug_691386.cpp",
"$_gm/crbug_788500.cpp",

16
src/gpu/geometry/GrQuadUtils.cpp
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@ -27,11 +27,13 @@ static constexpr float kInvDistTolerance = 1.f / kDistTolerance;
// These rotate the points/edge values either clockwise or counterclockwise assuming tri strip
// order.
static AI V4f next_cw(const V4f& v) {
template<typename T>
static AI skvx::Vec<4, T> next_cw(const skvx::Vec<4, T>& v) {
return skvx::shuffle<2, 0, 3, 1>(v);
}
static AI V4f next_ccw(const V4f& v) {
template<typename T>
static AI skvx::Vec<4, T> next_ccw(const skvx::Vec<4, T>& v) {
return skvx::shuffle<1, 3, 0, 2>(v);
}
@ -776,6 +778,7 @@ int TessellationHelper::EdgeEquations::computeDegenerateQuad(const V4f& signedEd
0.25f * ((*y2d)[0] + (*y2d)[1] + (*y2d)[2] + (*y2d)[3])};
*x2d = center.fX;
*y2d = center.fY;
*aaMask = any(*aaMask);
return 1;
} else if (all(d1Or2)) {
// Degenerates to a line. Compare p[2] and p[3] to edge 0. If they are on the wrong side,
@ -784,10 +787,15 @@ int TessellationHelper::EdgeEquations::computeDegenerateQuad(const V4f& signedEd
// Edges 0 and 3 have crossed over, so make the line from average of (p0,p2) and (p1,p3)
*x2d = 0.5f * (skvx::shuffle<0, 1, 0, 1>(px) + skvx::shuffle<2, 3, 2, 3>(px));
*y2d = 0.5f * (skvx::shuffle<0, 1, 0, 1>(py) + skvx::shuffle<2, 3, 2, 3>(py));
// If edges 0 and 3 crossed then one must have AA but we moved both 2D points on the
// edge so we need moveTo() to be able to move both 3D points along the shared edge. So
// ensure both have AA.
*aaMask = *aaMask | M4f({1, 0, 0, 1});
} else {
// Edges 1 and 2 have crossed over, so make the line from average of (p0,p1) and (p2,p3)
*x2d = 0.5f * (skvx::shuffle<0, 0, 2, 2>(px) + skvx::shuffle<1, 1, 3, 3>(px));
*y2d = 0.5f * (skvx::shuffle<0, 0, 2, 2>(py) + skvx::shuffle<1, 1, 3, 3>(py));
*aaMask = *aaMask | M4f({0, 1, 1, 0});
}
return 2;
} else {
@ -834,8 +842,8 @@ int TessellationHelper::EdgeEquations::computeDegenerateQuad(const V4f& signedEd
// points we're computing here. If we have an AA edge and a non-AA edge we
// can only move along 1 edge, but now the point we're moving toward isn't
// on that edge. Thus, we provide an additional degree of freedom by turning
// AA on for both edges if either edge is AA.
*aaMask = *aaMask | (d1Or2 & skvx::shuffle<2, 0, 3, 1>(*aaMask));
// AA on for both edges if either edge is AA at each point.
*aaMask = *aaMask | (d1Or2 & next_cw(*aaMask)) | (next_ccw(d1Or2) & next_ccw(*aaMask));
*x2d = px;
*y2d = py;
return 3;

21
src/gpu/ops/GrQuadPerEdgeAA.cpp
View File

@ -327,8 +327,18 @@ void Tessellator::append(GrQuad* deviceQuad, GrQuad* localQuad,
// a geometry subset if corners are not right angles
SkRect geomSubset;
if (fVertexSpec.requiresGeometrySubset()) {
#ifdef SK_USE_LEGACY_AA_QUAD_SUBSET
geomSubset = deviceQuad->bounds();
geomSubset.outset(0.5f, 0.5f); // account for AA expansion
#else
// Our GP code expects a 0.5 outset rect (coverage is computed as 0 at the values of
// the uniform). However, if we have quad edges that aren't supposed to be antialiased
// they may lie close to the bounds. So in that case we outset by an additional 0.5.
// This is a sort of backup clipping mechanism for cases where quad outsetting of nearly
// parallel edges produces long thin extrusions from the original geometry.
float outset = aaFlags == GrQuadAAFlags::kAll ? 0.5f : 1.f;
geomSubset = deviceQuad->bounds().makeOutset(outset, outset);
#endif
}
if (aaFlags == GrQuadAAFlags::kNone) {
@ -706,6 +716,7 @@ public:
args.fFragBuilder->codeAppend("float4 geoSubset;");
args.fVaryingHandler->addPassThroughAttribute(gp.fGeomSubset, "geoSubset",
Interpolation::kCanBeFlat);
#ifdef SK_USE_LEGACY_AA_QUAD_SUBSET
args.fFragBuilder->codeAppend(
"if (coverage < 0.5) {"
" float4 dists4 = clamp(float4(1, 1, -1, -1) * "
@ -713,6 +724,16 @@ public:
" float2 dists2 = dists4.xy * dists4.zw;"
" coverage = min(coverage, dists2.x * dists2.y);"
"}");
#else
args.fFragBuilder->codeAppend(
// This is lifted from GrAARectEffect. It'd be nice if we could
// invoke a FP from a GP rather than duplicate this code.
"half4 dists4 = clamp(half4(1, 1, -1, -1) * "
"half4(sk_FragCoord.xyxy - geoSubset), 0, 1);\n"
"half2 dists2 = dists4.xy + dists4.zw - 1;\n"
"half subsetCoverage = dists2.x * dists2.y;\n"
"coverage = min(coverage, subsetCoverage);");
#endif
}
args.fFragBuilder->codeAppendf("%s = half4(half(coverage));",