48 lines
1.4 KiB
C
48 lines
1.4 KiB
C
|
/*==============================================================================
|
||
|
|
|
||
|
|
Copyright 2018 by Roland Rabien, Devin Lane
|
||
|
|
For more information visit www.rabiensoftware.com
|
||
|
|
|
||
|
|
==============================================================================*/
|
||
|
|
|
||
|
|
#pragma once
|
||
|
|
|
||
|
|
/** Cubic spline interpolation is a simple way to obtain a smooth curve from a set of
|
||
|
|
discrete points. It has both C1 (first derivative) and C2 (second derivative) continuity,
|
||
|
|
enabling it to produce a continuous piecewise function given a set of data points.
|
||
|
|
|
||
|
|
Add points in increasing x order */
|
||
|
|
class Spline
|
||
|
|
{
|
||
|
|
public:
|
||
|
|
Spline (const Array<juce::Point<double>>& points);
|
||
|
|
|
||
|
|
double operator[] (double x) const;
|
||
|
|
double interpolate (double x) const;
|
||
|
|
|
||
|
|
class Element
|
||
|
|
{
|
||
|
|
public:
|
||
|
|
Element (double x_ = 0) : x (x_) {}
|
||
|
|
|
||
|
|
Element (double x_, double a_, double b_, double c_, double d_)
|
||
|
|
: x (x_), a (a_), b (b_), c (c_), d (d_) {}
|
||
|
|
|
||
|
|
double eval (double xx) const
|
||
|
|
{
|
||
|
|
double xix (xx - x);
|
||
|
|
return a + b * xix + c * (xix * xix) + d * (xix * xix * xix);
|
||
|
|
}
|
||
|
|
|
||
|
|
bool operator< (const Element& e) const { return x < e.x; }
|
||
|
|
bool operator< (const double xx) const { return x < xx; }
|
||
|
|
|
||
|
|
double x = 0, a = 0, b = 0, c = 0, d = 0;
|
||
|
|
};
|
||
|
|
|
||
|
|
private:
|
||
|
|
Array<Element> elements;
|
||
|
|
|
||
|
|
JUCE_LEAK_DETECTOR (Spline)
|
||
|
|
};
|