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// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0+ OR GPL-3.0 WITH Qt-GPL-exception-1.0
#include "mathutils.h"
#include <QtMath>
namespace Utils::MathUtils {
/*!
Linear interpolation:
For x = x1 it returns y1.
For x = x2 it returns y2.
*/
int interpolateLinear(int x, int x1, int x2, int y1, int y2)
{
if (x1 == x2)
return y1; // or the middle point between y1 and y2?
if (y1 == y2)
return y1;
if (x == x1)
return y1;
if (x == x2)
return y2;
const int numerator = (y2 - y1) * x + x2 * y1 - x1 * y2;
const int denominator = x2 - x1;
return qRound((double)numerator / denominator);
}
/*!
Tangential interpolation:
For x = 0 it returns y1.
For x = xHalfLife it returns 50 % of the distance between y1 and y2.
For x = infinity it returns y2.
*/
int interpolateTangential(int x, int xHalfLife, int y1, int y2)
{
if (x == 0)
return y1;
if (y1 == y2)
return y1;
const double angle = atan2((double)x, (double)xHalfLife);
const double result = y1 + (y2 - y1) * angle * 2 / M_PI;
return qRound(result);
}
/*!
Exponential interpolation:
For x = 0 it returns y1.
For x = xHalfLife it returns 50 % of the distance between y1 and y2.
For x = infinity it returns y2.
*/
int interpolateExponential(int x, int xHalfLife, int y1, int y2)
{
if (x == 0)
return y1;
if (y1 == y2)
return y1;
const double exponent = pow(0.5, (double)x / xHalfLife);
const double result = y1 + (y2 - y1) * (1.0 - exponent);
return qRound(result);
}
} // namespace Utils::MathUtils
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