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142 lines
6.2 KiB
142 lines
6.2 KiB
/*
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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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static void check_cubic_convex_180(skiatest::Reporter* r, const SkPoint p[4]) {
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bool areCusps = false;
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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, &areCusps);
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REPORTER_ASSERT(r, inflectN == convex180N);
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if (!areCusps) {
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REPORTER_ASSERT(r, inflectN == 1 ||
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fabsf(inflectT[0] - inflectT[1]) >= SK_ScalarNearlyZero);
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}
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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, &areCusps);
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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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REPORTER_ASSERT(r, !areCusps);
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} else {
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REPORTER_ASSERT(r, areCusps);
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}
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}
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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 covers every cubic type as
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// well as a wide variety of 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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check_cubic_convex_180(r, p);
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}
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{
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// This cubic has a convex-180 chop at T=1-"epsilon"
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static const uint32_t hexPts[] = {0x3ee0ac74, 0x3f1e061a, 0x3e0fc408, 0x3f457230,
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0x3f42ac7c, 0x3f70d76c, 0x3f4e6520, 0x3f6acafa};
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SkPoint p[4];
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memcpy(p, hexPts, sizeof(p));
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check_cubic_convex_180(r, p);
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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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bool areCusps;
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REPORTER_ASSERT(r, GrPathUtils::findCubicConvex180Chops(quad, T, &areCusps) == 0);
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// Now test that cusps and near-cusps get flagged as cusps.
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SkPoint cusp[4] = {{0,0}, {1,1}, {1,0}, {0,1}};
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REPORTER_ASSERT(r, GrPathUtils::findCubicConvex180Chops(cusp, T, &areCusps) == 1);
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REPORTER_ASSERT(r, areCusps == true);
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// Find the height of the right side of "cusp" at which the distance between its inflection
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// points is kEpsilon (in parametric space).
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constexpr static double kEpsilon = 1.0 / (1 << 11);
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constexpr static double kEpsilonSquared = kEpsilon * kEpsilon;
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double h = (1 - kEpsilonSquared) / (3 * kEpsilonSquared + 1);
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double dy = (1 - h) / 2;
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cusp[1].fY = (float)(1 - dy);
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cusp[2].fY = (float)(0 + dy);
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REPORTER_ASSERT(r, SkFindCubicInflections(cusp, T) == 2);
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REPORTER_ASSERT(r, SkScalarNearlyEqual(T[1] - T[0], (float)kEpsilon, (float)kEpsilonSquared));
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// Ensure two inflection points barely more than kEpsilon apart do not get flagged as cusps.
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cusp[1].fY = (float)(1 - 1.1 * dy);
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cusp[2].fY = (float)(0 + 1.1 * dy);
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REPORTER_ASSERT(r, GrPathUtils::findCubicConvex180Chops(cusp, T, &areCusps) == 2);
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REPORTER_ASSERT(r, areCusps == false);
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// Ensure two inflection points barely less than kEpsilon apart do get flagged as cusps.
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cusp[1].fY = (float)(1 - .9 * dy);
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cusp[2].fY = (float)(0 + .9 * dy);
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REPORTER_ASSERT(r, GrPathUtils::findCubicConvex180Chops(cusp, T, &areCusps) == 1);
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REPORTER_ASSERT(r, areCusps == true);
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}
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DEF_TEST(GrPathUtils_convertToCubic, r) {
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SkPoint cubic[4];
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GrPathUtils::convertLineToCubic({0,0}, {3,6}, cubic);
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REPORTER_ASSERT(r, cubic[0] == SkPoint::Make(0,0));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(cubic[1].fX, 1));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(cubic[1].fY, 2));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(cubic[2].fX, 2));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(cubic[2].fY, 4));
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REPORTER_ASSERT(r, cubic[3] == SkPoint::Make(3,6));
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SkPoint quad[3] = {{0,0}, {3,3}, {6,0}};
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GrPathUtils::convertQuadToCubic(quad, cubic);
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REPORTER_ASSERT(r, cubic[0] == SkPoint::Make(0,0));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(cubic[1].fX, 2));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(cubic[1].fY, 2));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(cubic[2].fX, 4));
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REPORTER_ASSERT(r, SkScalarNearlyEqual(cubic[2].fY, 2));
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REPORTER_ASSERT(r, cubic[3] == SkPoint::Make(6,0));
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}
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