Function normalize

docs/app/js/sanddance-app.js:69969–69977

(out, a)

    return out;
}
function normalize(out, a) {
    var x = a[0], y = a[1];
    var len1 = x * x + y * y;
    if (len1 > 0) //TODO: evaluate use of glm_invsqrt here?
    len1 = 1 / Math.sqrt(len1);
    out[0] = a[0] * len1;
    out[1] = a[1] * len1;
    return out;
}
function dot(a, b) {
    return a[0] * b[0] + a[1] * b[1];
}