three.js/src/extras/curves/CubicBezierCurve.js

import { Curve } from '../core/Curve.js';
import { CubicBezier } from '../core/Interpolations.js';
import { Vector2 } from '../../math/Vector2.js';

class CubicBezierCurve extends Curve {

	constructor( v0 = new Vector2(), v1 = new Vector2(), v2 = new Vector2(), v3 = new Vector2() ) {

		super();

		this.isCubicBezierCurve = true;

		this.type = 'CubicBezierCurve';

		this.v0 = v0;
		this.v1 = v1;
		this.v2 = v2;
		this.v3 = v3;

	}

	getPoint( t, optionalTarget = new Vector2() ) {

		const point = optionalTarget;

		const v0 = this.v0, v1 = this.v1, v2 = this.v2, v3 = this.v3;

		point.set(
			CubicBezier( t, v0.x, v1.x, v2.x, v3.x ),
			CubicBezier( t, v0.y, v1.y, v2.y, v3.y )
		);

		return point;

	}

	copy( source ) {

		super.copy( source );

		this.v0.copy( source.v0 );
		this.v1.copy( source.v1 );
		this.v2.copy( source.v2 );
		this.v3.copy( source.v3 );

		return this;

	}

	toJSON() {

		const data = super.toJSON();

		data.v0 = this.v0.toArray();
		data.v1 = this.v1.toArray();
		data.v2 = this.v2.toArray();
		data.v3 = this.v3.toArray();

		return data;

	}

	fromJSON( json ) {

		super.fromJSON( json );

		this.v0.fromArray( json.v0 );
		this.v1.fromArray( json.v1 );
		this.v2.fromArray( json.v2 );
		this.v3.fromArray( json.v3 );

		return this;

	}

}

export { CubicBezierCurve };