Method unitise

benchmark/bench/raytracer.java:17–17

(Vec a)

    Vec scale(double s, Vec a) { return new Vec(s*a.x, s*a.y, s*a.z); }
    double dot(Vec a, Vec b) { return a.x*b.x + a.y*b.y + a.z*b.z; }
    Vec unitise(Vec a) { return scale(1 / Math.sqrt(dot(a, a)), a); }
    class Ray {
        public Vec orig, dir;
        public Ray(Vec o, Vec d) { orig=o; dir=d; }