Method norm

generative/dla.rs:235–238

(v: &[f64; 2])

        (v[0] * v[0] + v[1] * v[1]).sqrt()
    }
    fn norm(v: &[f64; 2]) -> [f64; 2] {
        let l = Model::length(v);
        [v[0] / l, v[1] / l]
    }

    fn lerp(a: &[f64; 2], b: &[f64; 2], d: f64) -> [f64; 2] {
        // a + unit(b - a) * d