55 lines
1.3 KiB
C++
55 lines
1.3 KiB
C++
#include "math.h"
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#include <QtMath>
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#include <QVector>
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#include "debug.h"
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int lerp(int a, int b, double t) {
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return qRound(((1.0 - t) * a) + (t * b));
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}
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float float_lerp(float a, float b, float t) {
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return ((1.0F - t) * a) + (t * b);
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}
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double double_lerp(double a, double b, double t) {
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return ((1.0 - t) * a) + (t * b);
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}
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double quad_from_t(double a, double b, double c, double t) {
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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 quad_t_from_x(double x, double a, double b, double c) {
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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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// alt: 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 cubic_from_t(double a, double b, double c, double d, double t) {
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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 cubic_t_from_x(double x_target, double a, double b, double c, double d) {
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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 = cubic_from_t(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) / 2.0;
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x = cubic_from_t(a, b, c, d, percent);
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}
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return percent;
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}
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