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KBE3D / KBCore / Cesium / HermiteSpline

类: HermiteSpline ​

A Hermite spline is a cubic interpolating spline. Points, incoming tangents, outgoing tangents, and times must be defined for each control point. The outgoing tangents are defined for points [0, n - 2] and the incoming tangents are defined for points [1, n - 1]. For example, when interpolating a segment of the curve between <code>points[i]</code> and <code>points[i + 1]</code>, the tangents at the points will be <code>outTangents[i]</code> and <code>inTangents[i]</code>, respectively.

示例 ​

ts
// Create a G<sup>1</sup> continuous Hermite spline
const times = [ 0.0, 1.5, 3.0, 4.5, 6.0 ];
const spline = new Cesium.HermiteSpline({
    times : times,
    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)
    ],
    outTangents : [
        new Cesium.Cartesian3(1125196, -161816, 270551),
        new Cesium.Cartesian3(-996690.5, -365906.5, 184028.5),
        new Cesium.Cartesian3(-2096917, 48379.5, -292683.5),
        new Cesium.Cartesian3(-890902.5, 408999.5, -447115)
    ],
    inTangents : [
        new Cesium.Cartesian3(-1993381, -731813, 368057),
        new Cesium.Cartesian3(-4193834, 96759, -585367),
        new Cesium.Cartesian3(-1781805, 817999, -894230),
        new Cesium.Cartesian3(1165345, 112641, 47281)
    ]
});

const p0 = spline.evaluate(times[0]);

参数 ​

Object with the following properties:

参数 ​

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.

参数 ​

The array of control points.

参数 ​

The array of incoming tangents at each control point.

参数 ​

The array of outgoing tangents at each control point.

属性 ​

times ​

readonly times: number[]

An array of times for the control points.

points ​

readonly points: Cartesian3[]

An array of control points.

inTangents ​

readonly inTangents: Cartesian3[]

An array of incoming tangents at each control point.

outTangents ​

readonly outTangents: Cartesian3[]

An array of outgoing tangents at each control point.

方法 ​

createC1() ​

static createC1(options: { times: number[]; points: Cartesian3[]; tangents: Cartesian3[]; }): HermiteSpline

Creates a spline where the tangents at each control point are the same. The curves are guaranteed to be at least in the class C<sup>1</sup>.

参数 ​

options ​

Object with the following properties:

times ​

number[]

The array of control point times.

points ​

Cartesian3[]

The array of control points.

tangents ​

Cartesian3[]

The array of tangents at the control points.

返回 ​

HermiteSpline

A hermite spline.

示例 ​

ts
const 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)
];

// Add tangents
const tangents = new Array(points.length);
tangents[0] = new Cesium.Cartesian3(1125196, -161816, 270551);
const temp = new Cesium.Cartesian3();
for (let i = 1; i < tangents.length - 1; ++i) {
    tangents[i] = Cesium.Cartesian3.multiplyByScalar(Cesium.Cartesian3.subtract(points[i + 1], points[i - 1], temp), 0.5, new Cesium.Cartesian3());
}
tangents[tangents.length - 1] = new Cesium.Cartesian3(1165345, 112641, 47281);

const spline = Cesium.HermiteSpline.createC1({
    times : times,
    points : points,
    tangents : tangents
});

createNaturalCubic() ​

static createNaturalCubic(options: { times: number[]; points: Cartesian3[]; }): HermiteSpline | LinearSpline

Creates a natural cubic spline. The tangents at the control points are generated to create a curve in the class C<sup>2</sup>.

参数 ​

options ​

Object with the following properties:

times ​

number[]

The array of control point times.

points ​

Cartesian3[]

The array of control points.

返回 ​

HermiteSpline | LinearSpline

A hermite spline, or a linear spline if less than 3 control points were given.

示例 ​

ts
// Create a natural cubic spline above the earth from Philadelphia to Los Angeles.
const spline = Cesium.HermiteSpline.createNaturalCubic({
    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)
    ]
});

createClampedCubic() ​

static createClampedCubic(options: { times: number[]; points: number[] | Cartesian3[]; firstTangent: Cartesian3; lastTangent: Cartesian3; }): HermiteSpline | LinearSpline

Creates a clamped cubic spline. The tangents at the interior control points are generated to create a curve in the class C<sup>2</sup>.

参数 ​

options ​

Object with the following properties:

times ​

number[]

The array of control point times.

points ​

number[] | Cartesian3[]

The array of control points.

firstTangent ​

Cartesian3

The outgoing tangent of the first control point.

lastTangent ​

Cartesian3

The incoming tangent of the last control point.

返回 ​

HermiteSpline | LinearSpline

A hermite spline, or a linear spline if less than 3 control points were given.

示例 ​

ts
// Create a clamped cubic spline above the earth from Philadelphia to Los Angeles.
const spline = Cesium.HermiteSpline.createClampedCubic({
    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)
    ],
    firstTangent : new Cesium.Cartesian3(1125196, -161816, 270551),
    lastTangent : new Cesium.Cartesian3(1165345, 112641, 47281)
});

findTimeInterval() ​

findTimeInterval(time: number): number

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

参数 ​

time ​

number

The time.

返回 ​

number

The index for the element at the start of the interval.

wrapTime() ​

wrapTime(time: number): number

Wraps the given time to the period covered by the spline.

参数 ​

time ​

number

The time.

返回 ​

number

The time, wrapped around to the updated animation.

clampTime() ​

clampTime(time: number): number

Clamps the given time to the period covered by the spline.

参数 ​

time ​

number

The time.

返回 ​

number

The time, clamped to the animation period.

evaluate() ​

evaluate(time: number, result?: Cartesian3): Cartesian3

Evaluates the curve at a given time.

参数 ​

time ​

number

The time at which to evaluate the curve.

result? ​

Cartesian3

The object onto which to store the result.

返回 ​

Cartesian3

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

构造函数 ​

构造函数 ​

new HermiteSpline(options: { times: number[]; points: Cartesian3[]; inTangents: Cartesian3[]; outTangents: Cartesian3[]; }): HermiteSpline

参数 ​

options ​
times ​

number[]

points ​

Cartesian3[]

inTangents ​

Cartesian3[]

outTangents ​

Cartesian3[]

返回 ​

HermiteSpline

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