@woosh/meep-engine/src/core/geom/random/randomPointOnBox.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 *
 * @param {function} random
 * @param {number[]} result
 * @param {number} result_offset
 */
export function randomPointOnBox(random, result, result_offset) {
    //pick a side
    const side = random();

    //determine axis of the side
    const axis = side % 0.5;

    //convert side and axis to a fixed value for the axis
    const fixedAxis = side > 0.5 ? -0.5 : 0.5;

    let x, y, z;

    if (axis < 0.16666666666) {
        x = fixedAxis;
        y = random() - 0.5;
        z = random() - 0.5;
    } else if (axis < 0.33333333333) {
        x = random() - 0.5;
        y = fixedAxis;
        z = random() - 0.5;
    } else {
        x = random() - 0.5;
        y = random() - 0.5;
        z = fixedAxis;
    }

    //write the result
    result[result_offset] = x;
    result[result_offset + 1] = y;
    result[result_offset + 2] = z;
}