1 /* 2 * Copyright 2018 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "SkCubicMap.h" 9 #include "SkNx.h" 10 #include "../../src/pathops/SkPathOpsCubic.h" 11 12 void SkCubicMap::setPts(SkPoint p1, SkPoint p2) { 13 Sk2s s1 = Sk2s::Load(&p1) * 3; 14 Sk2s s2 = Sk2s::Load(&p2) * 3; 15 16 s1 = Sk2s::Min(Sk2s::Max(s1, 0), 3); 17 s2 = Sk2s::Min(Sk2s::Max(s2, 0), 3); 18 19 (Sk2s(1) + s1 - s2).store(&fCoeff[0]); 20 (s2 - s1 - s1).store(&fCoeff[1]); 21 s1.store(&fCoeff[2]); 22 23 this->buildXTable(); 24 } 25 26 SkPoint SkCubicMap::computeFromT(float t) const { 27 Sk2s a = Sk2s::Load(&fCoeff[0]); 28 Sk2s b = Sk2s::Load(&fCoeff[1]); 29 Sk2s c = Sk2s::Load(&fCoeff[2]); 30 31 SkPoint result; 32 (((a * t + b) * t + c) * t).store(&result); 33 return result; 34 } 35 36 float SkCubicMap::computeYFromX(float x) const { 37 x = SkTPin<float>(x, 0, 0.99999f) * kTableCount; 38 float ix = sk_float_floor(x); 39 int index = (int)ix; 40 SkASSERT((unsigned)index < SK_ARRAY_COUNT(fXTable)); 41 return this->computeFromT(fXTable[index].fT0 + fXTable[index].fDT * (x - ix)).fY; 42 } 43 44 float SkCubicMap::hackYFromX(float x) const { 45 x = SkTPin<float>(x, 0, 0.99999f) * kTableCount; 46 float ix = sk_float_floor(x); 47 int index = (int)ix; 48 SkASSERT((unsigned)index < SK_ARRAY_COUNT(fXTable)); 49 return fXTable[index].fY0 + fXTable[index].fDY * (x - ix); 50 } 51 52 static float compute_t_from_x(float A, float B, float C, float x) { 53 double roots[3]; 54 SkDEBUGCODE(int count =) SkDCubic::RootsValidT(A, B, C, -x, roots); 55 SkASSERT(count == 1); 56 return (float)roots[0]; 57 } 58 59 void SkCubicMap::buildXTable() { 60 float prevT = 0; 61 62 const float dx = 1.0f / kTableCount; 63 float x = dx; 64 65 fXTable[0].fT0 = 0; 66 fXTable[0].fY0 = 0; 67 for (int i = 1; i < kTableCount; ++i) { 68 float t = compute_t_from_x(fCoeff[0].fX, fCoeff[1].fX, fCoeff[2].fX, x); 69 SkASSERT(t > prevT); 70 71 fXTable[i - 1].fDT = t - prevT; 72 fXTable[i].fT0 = t; 73 74 SkPoint p = this->computeFromT(t); 75 fXTable[i - 1].fDY = p.fY - fXTable[i - 1].fY0; 76 fXTable[i].fY0 = p.fY; 77 78 prevT = t; 79 x += dx; 80 } 81 fXTable[kTableCount - 1].fDT = 1 - prevT; 82 fXTable[kTableCount - 1].fDY = 1 - fXTable[kTableCount - 1].fY0; 83 } 84
