CatmullRomSpline

new CatmullRomSpline

A Catmull-Rom spline is a cubic spline where the tangent at control points, except the first and last, are computed using the previous and next control points. Catmull-Rom splines are in the class C¹.

Parameters:

Name	Type	Argument	Description
`options.times`	Array		An array of strictly increasing, unit-less, floating-point times at each point. The values are in no way connected to the clock time. They are the parameterization for the curve.
`options.points`	Array		The array of Cartesian3 control points.
`options.firstTangent`	Cartesian3	<optional>	The tangent of the curve at the first control point. If the tangent is not given, it will be estimated.
`options.lastTangent`	Cartesian3	<optional>	The tangent of the curve at the last control point. If the tangent is not given, it will be estimated.

Throws:

DeveloperError : points.length must be greater than or equal to 2.
DeveloperError : times.length must be equal to points.length.

Example

// spline above the earth from Philadelphia to Los Angeles
var spline = new Cesium.CatmullRomSpline({
    times : [ 0.0, 1.5, 3.0, 4.5, 6.0 ],
    points : [
        new Cesium.Cartesian3(1235398.0, -4810983.0, 4146266.0),
        new Cesium.Cartesian3(1372574.0, -5345182.0, 4606657.0),
        new Cesium.Cartesian3(-757983.0, -5542796.0, 4514323.0),
        new Cesium.Cartesian3(-2821260.0, -5248423.0, 4021290.0),
        new Cesium.Cartesian3(-2539788.0, -4724797.0, 3620093.0)
    ]
});

var p0 = spline.evaluate(times[i]);         // equal to positions[i]
var p1 = spline.evaluate(times[i] + delta); // interpolated value when delta < times[i + 1] - times[i]

See:

Source:

llRomSpline.js

Members

findTimeInterval :DeveloperError

Finds an index i in times such that the parameter time is in the interval [times[i], times[i + 1]].

<readonly> firstTangent :Cartesian3

The tangent at the first control point.

<readonly> lastTangent :Cartesian3

The tangent at the last control point.

<readonly> points :Array

An array of Cartesian3 control points.

<readonly> times :Array

An array of times for the control points.

Methods

evaluate

Evaluates the curve at a given time.

Parameters:

Name	Type	Argument	Description
`time`	Number		The time at which to evaluate the curve.
`result`	Cartesian3	<optional>	The object onto which to store the result.

Throws:

DeveloperError : time must be in the range [t₀, t_n], where t₀ is the first element in the array times and t_n is the last element in the array times.

Returns:

Cartesian3 The modified result parameter or a new instance of the point on the curve at the given time.