2882e70ef3
This method finds the locations a cubic needs to be chopped at before it can be passed to the stroke tessellation shader. It's an integral part of CPU stroke preparation and therefore extremely perf sensitive. Bug: skia:10419 Change-Id: Ib23c2583b8cfc78814ce52425f7af2c8b2f8b420 Reviewed-on: https://skia-review.googlesource.com/c/skia/+/330314 Commit-Queue: Chris Dalton <csmartdalton@google.com> Reviewed-by: Michael Ludwig <michaelludwig@google.com>
72 lines
3.2 KiB
C++
72 lines
3.2 KiB
C++
/*
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* Copyright 2020 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "include/utils/SkRandom.h"
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#include "src/core/SkGeometry.h"
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#include "src/gpu/geometry/GrPathUtils.h"
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#include "tests/Test.h"
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static bool is_linear(SkPoint p0, SkPoint p1, SkPoint p2) {
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return SkScalarNearlyZero((p0 - p1).cross(p2 - p1));
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}
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static bool is_linear(const SkPoint p[4]) {
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return is_linear(p[0],p[1],p[2]) && is_linear(p[0],p[2],p[3]) && is_linear(p[1],p[2],p[3]);
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}
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DEF_TEST(GrPathUtils_findCubicConvex180Chops, r) {
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// Test all combinations of corners from the square [0,0,1,1]. This gives us all kinds of
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// special cases for cusps, lines, loops, and inflections.
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for (int i = 0; i < (1 << 8); ++i) {
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SkPoint p[4] = {SkPoint::Make((i>>0)&1, (i>>1)&1),
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SkPoint::Make((i>>2)&1, (i>>3)&1),
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SkPoint::Make((i>>4)&1, (i>>5)&1),
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SkPoint::Make((i>>6)&1, (i>>7)&1)};
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float inflectT[2], convex180T[2];
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if (int inflectN = SkFindCubicInflections(p, inflectT)) {
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// The curve has inflections. findCubicConvex180Chops should return the inflection
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// points.
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int convex180N = GrPathUtils::findCubicConvex180Chops(p, convex180T);
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REPORTER_ASSERT(r, inflectN == convex180N);
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for (int i = 0; i < convex180N; ++i) {
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REPORTER_ASSERT(r, SkScalarNearlyEqual(inflectT[i], convex180T[i]));
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}
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} else {
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float totalRotation = SkMeasureNonInflectCubicRotation(p);
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int convex180N = GrPathUtils::findCubicConvex180Chops(p, convex180T);
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SkPoint chops[10];
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SkChopCubicAt(p, chops, convex180T, convex180N);
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float radsSum = 0;
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for (int i = 0; i <= convex180N; ++i) {
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float rads = SkMeasureNonInflectCubicRotation(chops + i*3);
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SkASSERT(rads < SK_ScalarPI + SK_ScalarNearlyZero);
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radsSum += rads;
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}
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if (totalRotation < SK_ScalarPI - SK_ScalarNearlyZero) {
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// The curve should never chop if rotation is <180 degrees.
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REPORTER_ASSERT(r, convex180N == 0);
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} else if (!is_linear(p)) {
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REPORTER_ASSERT(r, SkScalarNearlyEqual(radsSum, totalRotation));
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if (totalRotation > SK_ScalarPI + SK_ScalarNearlyZero) {
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REPORTER_ASSERT(r, convex180N == 1);
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// This works because cusps take the "inflection" path above, so we don't get
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// non-lilnear curves that lose rotation when chopped.
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REPORTER_ASSERT(r, SkScalarNearlyEqual(
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SkMeasureNonInflectCubicRotation(chops), SK_ScalarPI));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(
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SkMeasureNonInflectCubicRotation(chops + 3), totalRotation - SK_ScalarPI));
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}
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}
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}
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}
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// Now test an exact quadratic.
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SkPoint quad[4] = {{0,0}, {2,2}, {4,2}, {6,0}};
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float T[2];
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REPORTER_ASSERT(r, GrPathUtils::findCubicConvex180Chops(quad, T) == 0);
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}
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