@woosh/meep-engine/src/engine/graphics/ecs/path/tube/build/estimatePathViaIterativeIntegral.js

Pure JavaScript game engine. Fully featured and production ready.

import { Vector3 } from "three";

/**
 * some useful references:
 * https://stackoverflow.com/questions/29438398/cheap-way-of-calculating-cubic-bezier-length
 * https://stackoverflow.com/questions/1147249/connecting-catmull-rom-splines-together-and-calculating-its-length
 * @param {Path} path
 * @param {number} epsilon
 */
export function estimatePathViaIterativeIntegral(path, epsilon) {
    let sum = 0;

    let p0 = new Vector3();
    let p1 = new Vector3();

    if (!path.sample(p0, 0)) {
        // path has 0 length
        return 0;
    }

    for (let p = epsilon; ; p += epsilon) {
        const ended = path.sample(p1, p);

        if (ended) {
            break;
        }

        sum += p0.distanceTo(p1);

        const swap = p1;

        p1 = p0;
        p0 = swap;
    }

    return sum;
}