transformMat4.js

module.exports = transformMat4;

/**
 * Transforms the vec3 with a mat4.
 * 4th vector component is implicitly '1'
 *
 * @param {vec3} out the receiving vector
 * @param {vec3} a the vector to transform
 * @param {mat4} m matrix to transform with
 * @returns {vec3} out
 */
function transformMat4(out, a, m) {
    var x = a[0], y = a[1], z = a[2],
        w = m[3] * x + m[7] * y + m[11] * z + m[15]
    w = w || 1.0
    out[0] = (m[0] * x + m[4] * y + m[8] * z + m[12]) / w
    out[1] = (m[1] * x + m[5] * y + m[9] * z + m[13]) / w
    out[2] = (m[2] * x + m[6] * y + m[10] * z + m[14]) / w
    return out
}