77 lines
1.9 KiB
C++
77 lines
1.9 KiB
C++
/***
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Olive - Non-Linear Video Editor
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Copyright (C) 2021 Olive Team
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "bezier.h"
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#include <QtMath>
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#include "common/clamp.h"
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namespace olive {
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double Bezier::QuadraticXtoT(double x, double a, double b, double c)
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{
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// Clamp to prevent infinite loop
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x = clamp(x, a, c);
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return CalculateTFromX(false, x, a, b, c, 0);
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}
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double Bezier::QuadraticTtoY(double a, double b, double c, double t)
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{
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return qPow(1.0 - t, 2)*a + 2*(1.0 - t)*t*b + qPow(t, 2)*c;
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}
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double Bezier::CubicXtoT(double x, double a, double b, double c, double d)
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{
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// Clamp to prevent infinite loop
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x = clamp(x, a, d);
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return CalculateTFromX(true, x, a, b, c, d);
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}
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double Bezier::CubicTtoY(double a, double b, double c, double d, double t)
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{
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return qPow(1.0 - t, 3)*a + 3*qPow(1.0 - t, 2)*t*b + 3*(1.0 - t)*qPow(t, 2)*c + qPow(t, 3)*d;
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}
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double Bezier::CalculateTFromX(bool cubic, double x, double a, double b, double c, double d)
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{
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double bottom = 0.0;
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double top = 1.0;
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while (true) {
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double mid = (bottom + top) * 0.5;
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double test = cubic ? CubicTtoY(a, b, c, d, mid) : QuadraticTtoY(a, b, c, mid);
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if (qFuzzyCompare(test, x)) {
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return mid;
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} else if (x > test) {
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bottom = mid;
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} else {
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top = mid;
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}
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}
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return qSNaN();
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}
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}
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