| /* |
| * 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; |
| } |