phaser/src/math/interpolation/BezierInterpolation.js

A fast, free and fun HTML5 Game Framework for Desktop and Mobile web browsers from the team at Phaser Studio Inc.

/**
 * @author       Richard Davey <rich@phaser.io>
 * @copyright    2013-2026 Phaser Studio Inc.
 * @license      {@link https://opensource.org/licenses/MIT|MIT License}
 */

var Bernstein = require('../Bernstein');

/**
 * Performs a generalized Bezier interpolation over an arbitrary number of control points.
 * The `v` array provides the control point values and `k` (0 to 1) determines the position
 * along the curve. Unlike CubicBezierInterpolation which uses exactly 4 points, this
 * supports any number.
 *
 * @function Phaser.Math.Interpolation.Bezier
 * @since 3.0.0
 *
 * @param {number[]} v - The input array of values to interpolate between.
 * @param {number} k - The percentage of interpolation, between 0 and 1.
 *
 * @return {number} The interpolated value.
 */
var BezierInterpolation = function (v, k)
{
    var b = 0;
    var n = v.length - 1;

    for (var i = 0; i <= n; i++)
    {
        b += Math.pow(1 - k, n - i) * Math.pow(k, i) * v[i] * Bernstein(n, i);
    }

    return b;
};

module.exports = BezierInterpolation;