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- /*
- * Copyright 2018 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
- #include "include/core/SkCubicMap.h"
- #include "include/private/SkNx.h"
- #include "src/core/SkOpts.h"
- //#define CUBICMAP_TRACK_MAX_ERROR
- #ifdef CUBICMAP_TRACK_MAX_ERROR
- #include "src/pathops/SkPathOpsCubic.h"
- #endif
- static inline bool nearly_zero(SkScalar x) {
- SkASSERT(x >= 0);
- return x <= 0.0000000001f;
- }
- #ifdef CUBICMAP_TRACK_MAX_ERROR
- static int max_iters;
- #endif
- #ifdef CUBICMAP_TRACK_MAX_ERROR
- static float compute_slow(float A, float B, float C, float x) {
- double roots[3];
- SkDEBUGCODE(int count =) SkDCubic::RootsValidT(A, B, C, -x, roots);
- SkASSERT(count == 1);
- return (float)roots[0];
- }
- static float max_err;
- #endif
- static float compute_t_from_x(float A, float B, float C, float x) {
- #ifdef CUBICMAP_TRACK_MAX_ERROR
- float answer = compute_slow(A, B, C, x);
- #endif
- float answer2 = SkOpts::cubic_solver(A, B, C, -x);
- #ifdef CUBICMAP_TRACK_MAX_ERROR
- float err = sk_float_abs(answer - answer2);
- if (err > max_err) {
- max_err = err;
- SkDebugf("max error %g\n", max_err);
- }
- #endif
- return answer2;
- }
- float SkCubicMap::computeYFromX(float x) const {
- x = SkScalarPin(x, 0, 1);
- if (nearly_zero(x) || nearly_zero(1 - x)) {
- return x;
- }
- if (fType == kLine_Type) {
- return x;
- }
- float t;
- if (fType == kCubeRoot_Type) {
- t = sk_float_pow(x / fCoeff[0].fX, 1.0f / 3);
- } else {
- t = compute_t_from_x(fCoeff[0].fX, fCoeff[1].fX, fCoeff[2].fX, x);
- }
- float a = fCoeff[0].fY;
- float b = fCoeff[1].fY;
- float c = fCoeff[2].fY;
- float y = ((a * t + b) * t + c) * t;
- return y;
- }
- static inline bool coeff_nearly_zero(float delta) {
- return sk_float_abs(delta) <= 0.0000001f;
- }
- SkCubicMap::SkCubicMap(SkPoint p1, SkPoint p2) {
- // Clamp X values only (we allow Ys outside [0..1]).
- p1.fX = SkTMin(SkTMax(p1.fX, 0.0f), 1.0f);
- p2.fX = SkTMin(SkTMax(p2.fX, 0.0f), 1.0f);
- Sk2s s1 = Sk2s::Load(&p1) * 3;
- Sk2s s2 = Sk2s::Load(&p2) * 3;
- (Sk2s(1) + s1 - s2).store(&fCoeff[0]);
- (s2 - s1 - s1).store(&fCoeff[1]);
- s1.store(&fCoeff[2]);
- fType = kSolver_Type;
- if (SkScalarNearlyEqual(p1.fX, p1.fY) && SkScalarNearlyEqual(p2.fX, p2.fY)) {
- fType = kLine_Type;
- } else if (coeff_nearly_zero(fCoeff[1].fX) && coeff_nearly_zero(fCoeff[2].fX)) {
- fType = kCubeRoot_Type;
- }
- }
- SkPoint SkCubicMap::computeFromT(float t) const {
- Sk2s a = Sk2s::Load(&fCoeff[0]);
- Sk2s b = Sk2s::Load(&fCoeff[1]);
- Sk2s c = Sk2s::Load(&fCoeff[2]);
- SkPoint result;
- (((a * t + b) * t + c) * t).store(&result);
- return result;
- }
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