Path3 implementation of three.js (r84)

Path3.js

Path3.prototype = Object.create( THREE.Curve.prototype );
Path3.prototype.constructor = Path3;

Path3.prototype.getPoint = function ( t ) {
    var points = this.points;
    var l = points.length;

    if ( l < 2 ) console.log( 'duh, you need at least 2 points' );

    var point = ( l - 1 ) * t;
    var intPoint = Math.floor( point );
    var weight = point - intPoint;

    if ( weight === 0 && intPoint === l - 1 ) {
        intPoint = l - 2;
        weight = 1;

    }

    var p1 = points[ intPoint % l ];
    var p2 = points[ ( intPoint + 1 ) % l ];
  
  return p1.clone().lerp( p2, weight );
}

Path3.ts

import * as THREE from "three";


export class Path3 extends THREE.CatmullRomCurve3 {
    getPoint(t: number) {
        const points = this.points;
        const l = points.length;

        if (l < 2) {
            console.log("duh, you need at least 2 points");
        }

        const point = (l - 1) * t;
        let intPoint = Math.floor(point);
        let weight = point - intPoint;

        if ( weight === 0 && intPoint === l - 1 ) {
            intPoint = l - 2;
            weight = 1;
        }

        const p1 = points[intPoint % l];
        const p2 = points[(intPoint + 1) % l];
  
        return p1.clone().lerp(p2, weight);
    }
}