67 lines
1.7 KiB
C++
67 lines
1.7 KiB
C++
/***
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Olive - Non-Linear Video Editor
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Copyright (C) 2020 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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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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return (a - b + qSqrt(a*x + c*x - 2*b*x + qPow(b, 2) - a*c))/(a - 2*b + c);
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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_target, double a, double b, double c, double d)
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{
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const double tolerance = 0.0001;
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double lower = 0.0;
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double upper = 1.0;
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double percent = 0.5;
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double x = CubicTtoY(a, b, c, d, percent);
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while (qAbs(x_target - x) > tolerance) {
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if (x_target > x) {
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lower = percent;
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} else {
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upper = percent;
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}
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percent = (upper + lower) * 0.5;
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x = CubicTtoY(a, b, c, d, percent);
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}
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return percent;
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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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}
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