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74 lines
2.0 KiB
74 lines
2.0 KiB
/*
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* Copyright 2018 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 "SkCubicMap.h"
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#include "SkGeometry.h"
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#include "SkRandom.h"
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#include "Test.h"
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#include "../../src/pathops/SkPathOpsCubic.h"
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static float accurate_t(float A, float B, float C, float D) {
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double roots[3];
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SkDEBUGCODE(int count =) SkDCubic::RootsValidT(A, B, C, D, roots);
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SkASSERT(count == 1);
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return (float)roots[0];
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}
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static float accurate_solve(SkPoint p1, SkPoint p2, SkScalar x) {
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SkPoint array[] = { {0, 0}, p1, p2, {1,1} };
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SkCubicCoeff coeff(array);
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float t = accurate_t(coeff.fA[0], coeff.fB[0], coeff.fC[0], coeff.fD[0] - x);
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SkASSERT(t >= 0 && t <= 1);
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float y = coeff.eval(t)[1];
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SkASSERT(y >= 0 && y <= 1.0001f);
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return y;
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}
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static bool nearly_le(SkScalar a, SkScalar b) {
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return a <= b || SkScalarNearlyZero(a - b);
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}
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static void exercise_cubicmap(SkPoint p1, SkPoint p2, skiatest::Reporter* reporter) {
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const SkScalar MAX_SOLVER_ERR = 0.008f; // found by running w/ current impl
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SkCubicMap cmap(p1, p2);
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SkScalar prev_y = 0;
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SkScalar dx = 1.0f / 512;
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for (SkScalar x = dx; x < 1; x += dx) {
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SkScalar y = cmap.computeYFromX(x);
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// are we valid and (mostly) monotonic?
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if (y < 0 || y > 1 || !nearly_le(prev_y, y)) {
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cmap.computeYFromX(x);
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REPORTER_ASSERT(reporter, false);
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}
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prev_y = y;
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// are we close to the "correct" answer?
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SkScalar yy = accurate_solve(p1, p2, x);
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SkScalar diff = SkScalarAbs(yy - y);
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REPORTER_ASSERT(reporter, diff < MAX_SOLVER_ERR);
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}
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}
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DEF_TEST(CubicMap, r) {
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const SkScalar values[] = {
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0, 1, 0.5f, 0.0000001f, 0.999999f,
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};
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for (SkScalar x0 : values) {
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for (SkScalar y0 : values) {
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for (SkScalar x1 : values) {
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for (SkScalar y1 : values) {
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exercise_cubicmap({ x0, y0 }, { x1, y1 }, r);
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}
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}
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}
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}
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}
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