implemented bezier interpolation into parameters inputs

app/common/CMakeLists.txt

@@ -16,6 +16,8 @@
 
 set(OLIVE_SOURCES
   ${OLIVE_SOURCES}
+  common/bezier.h
+  common/bezier.cpp
   common/channellayout.h
   common/clamp.h
   common/constructors.h

app/common/bezier.cpp

@@ -0,0 +1,42 @@
+#include "bezier.h"
+
+#include <QtMath>
+
+double Bezier::QuadraticXtoT(double x, double a, double b, double c)
+{
+  return (a - b + qSqrt(a*x + c*x - 2*b*x + qPow(b, 2) - a*c))/(a - 2*b + c);
+}
+
+double Bezier::QuadraticTtoY(double a, double b, double c, double t)
+{
+  return qPow(1.0 - t, 2)*a + 2*(1.0 - t)*t*b + qPow(t, 2)*c;
+}
+
+double Bezier::CubicXtoT(double x_target, double a, double b, double c, double d)
+{
+  double tolerance = 0.0001;
+
+  double lower = 0.0;
+  double upper = 1.0;
+
+  double percent = 0.5;
+  double x = CubicTtoY(a, b, c, d, percent);
+
+  while (qAbs(x_target - x) > tolerance) {
+    if (x_target > x) {
+      lower = percent;
+    } else {
+      upper = percent;
+    }
+
+    percent = (upper + lower) / 2.0;
+    x = CubicTtoY(a, b, c, d, percent);
+  }
+
+  return percent;
+}
+
+double Bezier::CubicTtoY(double a, double b, double c, double d, double t)
+{
+  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;
+}

app/common/bezier.h

@@ -0,0 +1,17 @@
+#ifndef BEZIER_H
+#define BEZIER_H
+
+
+class Bezier
+{
+public:
+  static double QuadraticXtoT(double x, double a, double b, double c);
+
+  static double QuadraticTtoY(double a, double b, double c, double t);
+
+  static double CubicXtoT(double x_target, double a, double b, double c, double d);
+
+  static double CubicTtoY(double a, double b, double c, double d, double t);
+};
+
+#endif // BEZIER_H