@woosh/meep-engine/src/core/geom/vec3/v3_array_centroid.js

Pure JavaScript game engine. Fully featured and production ready.

import { assert } from "../../assert.js";

/**
 * Compute average-weighted centroid of a set of 3d vectors
 * @param {number[]} out
 * @param {number} out_offset where to start writing the result
 * @param {number[]} input
 * @param {number} input_offset where to start reading
 * @param {number} count how many elements to use
 * @returns {number[]} same as the `out` parameter, returned for convenience
 */
export function v3_array_centroid(out, out_offset, input, input_offset, count) {
    assert.isNonNegativeInteger(out_offset, 'out_offset');
    assert.isNonNegativeInteger(input_offset, 'input_offset');
    assert.isNonNegativeInteger(count, 'count');

    let x = 0;
    let y = 0;
    let z = 0;

    for (let i = 0; i < count; i++) {
        const offset = input_offset + i * 3;

        x += input[offset];
        y += input[offset + 1];
        z += input[offset + 2];
    }

    if (count > 0) { // avoid division by zero
        x /= count;
        y /= count;
        z /= count;
    }

    out[out_offset] = x;
    out[out_offset + 1] = y;
    out[out_offset + 2] = z;

    return out;
}