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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 "SkCubicMap.h"
#include "SkNx.h"
#include "../../src/pathops/SkPathOpsCubic.h"
void SkCubicMap::setPts(SkPoint p1, SkPoint p2) {
Sk2s s1 = Sk2s::Load(&p1) * 3;
Sk2s s2 = Sk2s::Load(&p2) * 3;
s1 = Sk2s::Min(Sk2s::Max(s1, 0), 3);
s2 = Sk2s::Min(Sk2s::Max(s2, 0), 3);
(Sk2s(1) + s1 - s2).store(&fCoeff[0]);
(s2 - s1 - s1).store(&fCoeff[1]);
s1.store(&fCoeff[2]);
this->buildXTable();
}
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;
}
float SkCubicMap::computeYFromX(float x) const {
x = SkTPin<float>(x, 0, 0.99999f) * kTableCount;
float ix = sk_float_floor(x);
int index = (int)ix;
SkASSERT((unsigned)index < SK_ARRAY_COUNT(fXTable));
return this->computeFromT(fXTable[index].fT0 + fXTable[index].fDT * (x - ix)).fY;
}
float SkCubicMap::hackYFromX(float x) const {
x = SkTPin<float>(x, 0, 0.99999f) * kTableCount;
float ix = sk_float_floor(x);
int index = (int)ix;
SkASSERT((unsigned)index < SK_ARRAY_COUNT(fXTable));
return fXTable[index].fY0 + fXTable[index].fDY * (x - ix);
}
static float compute_t_from_x(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];
}
void SkCubicMap::buildXTable() {
float prevT = 0;
const float dx = 1.0f / kTableCount;
float x = dx;
fXTable[0].fT0 = 0;
fXTable[0].fY0 = 0;
for (int i = 1; i < kTableCount; ++i) {
float t = compute_t_from_x(fCoeff[0].fX, fCoeff[1].fX, fCoeff[2].fX, x);
SkASSERT(t > prevT);
fXTable[i - 1].fDT = t - prevT;
fXTable[i].fT0 = t;
SkPoint p = this->computeFromT(t);
fXTable[i - 1].fDY = p.fY - fXTable[i - 1].fY0;
fXTable[i].fY0 = p.fY;
prevT = t;
x += dx;
}
fXTable[kTableCount - 1].fDT = 1 - prevT;
fXTable[kTableCount - 1].fDY = 1 - fXTable[kTableCount - 1].fY0;
}
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