JavaScript functions to get the position or index of a cube following the Sauerbraten octree structure

readme.md

sauer_octree_locator.js

// example: getCubeIndex(256, 256, 512, 8) // returns: 35
function getCubeIndex(x, y, z, gridpower) {
    let index = 0;
    let size = 1<<gridpower;
    index += parseInt((x / size).toString(2), 8);
    index += parseInt((y / size).toString(2), 8) * 2;
    index += parseInt((z / size).toString(2), 8) * 4;
    return index;
}

// example: getCubePos(35, 8) // returns: [256, 256, 512]
function getCubePos(index, gridpower) {
    let octal = index.toString(8);
    let size = 1<<gridpower;
    let position = [0, 0, 0];
    for (i = 0; i < octal.length; i++) {
        let digit = parseInt(octal[octal.length - i - 1], 8);
        position[0] += (Math.floor(digit / 1) % 2) * (2 ** i) * size;
        position[1] += (Math.floor(digit / 2) % 2) * (2 ** i) * size;
        position[2] += (Math.floor(digit / 4) % 2) * (2 ** i) * size;
    }
    return position;
}