CatmullRomSpline

new LSGlobe.CatmullRomSpline(options)
Core/CatmullRomSpline.js 148

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.
Name Type Description
options Object Object with the following properties:
Name Type Description
times Array.<Number> 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.
points Array.<Cartesian3> The array of Cartesian3 control points.
firstTangent Cartesian3 optional The tangent of the curve at the first control point. If the tangent is not given, it will be estimated.
lastTangent Cartesian3 optional The tangent of the curve at the last control point. If the tangent is not given, it will be estimated.
Throws:
Example:
// spline above the earth from Philadelphia to Los Angeles
var spline = new LSGlobe.CatmullRomSpline({
    times : [ 0.0, 1.5, 3.0, 4.5, 6.0 ],
    points : [
        new LSGlobe.Cartesian3(1235398.0, -4810983.0, 4146266.0),
        new LSGlobe.Cartesian3(1372574.0, -5345182.0, 4606657.0),
        new LSGlobe.Cartesian3(-757983.0, -5542796.0, 4514323.0),
        new LSGlobe.Cartesian3(-2821260.0, -5248423.0, 4021290.0),
        new LSGlobe.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:

Members

readonly firstTangent : Cartesian3
Core/CatmullRomSpline.js 233

The tangent at the first control point.

readonly lastTangent : Cartesian3
Core/CatmullRomSpline.js 247

The tangent at the last control point.

readonly points : Array.<Cartesian3>
Core/CatmullRomSpline.js 219

An array of Cartesian3 control points.

readonly times : Array.<Number>
Core/CatmullRomSpline.js 205

An array of times for the control points.

Methods

clampTime(time) → Number
Core/CatmullRomSpline.js 306

Clamps the given time to the period covered by the spline.
Name Type Description
time Number The time.
Returns:
The time, clamped to the animation period.

evaluate(time, result) → Cartesian3
Core/CatmullRomSpline.js 319

Evaluates the curve at a given time.
Name Type Description
time Number The time at which to evaluate the curve.
result Cartesian3 optional The object onto which to store the result.
Returns:
The modified result parameter or a new instance of the point on the curve at the given time.
Throws:
  • DeveloperError : time must be in the range [t0, tn], where t0 is the first element in the array times and tn is the last element in the array times.

findTimeInterval(time) → Number
Core/CatmullRomSpline.js 288

Finds an index i in times such that the parameter time is in the interval [times[i], times[i + 1]].
Name Type Description
time Number The time.
Returns:
The index for the element at the start of the interval.
Throws:
  • DeveloperError : time must be in the range [t0, tn], where t0 is the first element in the array times and tn is the last element in the array times.

wrapTime(time) → Number
Core/CatmullRomSpline.js 297

Wraps the given time to the period covered by the spline.
Name Type Description
time Number The time.
Returns:
The time, wrapped around to the updated animation.