com.androidplot.xy

Class CatmullRomInterpolator

java.lang.Object

com.androidplot.xy.CatmullRomInterpolator

All Implemented Interfaces:

Interpolator<CatmullRomInterpolator.Params>

public class CatmullRomInterpolator
extends Object
implements Interpolator<CatmullRomInterpolator.Params>

A primitive implementation of Catmull-Rom interpolation, based on the information found at: http://stackoverflow.com/questions/9489736/catmull-rom-curve-with-no-cusps-and-no-self-intersections/19283471#19283471

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	CatmullRomInterpolator.Params
static class	CatmullRomInterpolator.Type

Constructor Summary

Constructors

Constructor and Description
CatmullRomInterpolator()

Method Summary

Modifier and Type	Method and Description
static double	interpolate(double[] p, double[] time, double t) Unlike the other implementation here, which uses the default "uniform" treatment of t, this computation is used to calculate the same values but introduces the ability to "parameterize" the t values used in the calculation.
List<XYCoords>	interpolate(XYSeries series, CatmullRomInterpolator.Params params) This method will calculate the Catmull-Rom interpolation curve, returning it as a list of Coord coordinate objects.
List<XYCoords>	interpolate(XYSeries series, int index, CatmullRomInterpolator.Params params) Given a list of control points, this will create a list of pointsPerSegment points spaced uniformly along the resulting Catmull-Rom curve.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CatmullRomInterpolator

public CatmullRomInterpolator()

Method Detail

interpolate

public List<XYCoords> interpolate(XYSeries series,
                                  CatmullRomInterpolator.Params params)

This method will calculate the Catmull-Rom interpolation curve, returning it as a list of Coord coordinate objects. This method in particular adds the first and last control points which are not visible, but required for calculating the spline.

Specified by:

interpolate in interface Interpolator<CatmullRomInterpolator.Params>

Parameters:

series - The list of original straight line points to calculate an interpolation from.

Returns:

The list of interpolated coordinates.

Throws:

IllegalArgumentException - if pointsPerSegment is less than 2.

interpolate

public List<XYCoords> interpolate(XYSeries series,
                                  int index,
                                  CatmullRomInterpolator.Params params)

Given a list of control points, this will create a list of pointsPerSegment points spaced uniformly along the resulting Catmull-Rom curve.

Parameters:

series - The list of control points, leading and ending with a coordinate that is only used for controling the spline and is not visualized.

index - The index of control point p0, where p0, p1, p2, and p3 are used in order to create a curve between p1 and p2.

Returns:

the list of coordinates that define the CatmullRom curve between the points defined by index+1 and index+2.

interpolate

public static double interpolate(double[] p,
                                 double[] time,
                                 double t)

Unlike the other implementation here, which uses the default "uniform" treatment of t, this computation is used to calculate the same values but introduces the ability to "parameterize" the t values used in the calculation. This is based on Figure 3 from http://www.cemyuksel.com/research/catmullrom_param/catmullrom.pdf

Parameters:

p - An array of double values of length 4, where interpolation occurs from p1 to p2.

time - An array of time measures of length 4, corresponding to each p value.

t - the actual interpolation ratio from 0 to 1 representing the position between p1 and p2 to interpolate the value.

Returns: