/** 3D ray
 * @author: Phil Gage
 */
class Ray {
    Point origin;
    Vector3 direction;

    Ray () {
        this.origin = new Point ();
        this.direction = new Vector3 ();
    }

    Ray (Point origin, Vector3 direction) {
        this.origin = new Point (origin);
        this.direction = new Vector3 (direction);
    }

    // Reflect incident ray using normal
    static Vector3 reflect (Vector3 incident, Vector3 normal) {
        Vector3 r = new Vector3 ();
        double n = Vector3.dot(normal,normal);
        double i = Vector3.dot(normal,incident);
        r.x = incident.x-(2.0*i/n)*normal.x;
        r.y = incident.y-(2.0*i/n)*normal.y;
        r.z = incident.z-(2.0*i/n)*normal.z;
        return r;
    }

    // Refract incident ray using normal
//tbd

    // Project along (normalized) ray to get point
    Point extrapolate (double distance, Point p) {
        double m = this.direction.magnitude();
        p.x = origin.x + distance*direction.x/m;
        p.y = origin.y + distance*direction.y/m;
        p.z = origin.z + distance*direction.z/m;
        return p;
    }

    public String toString () {
        return "Ray dir x=" + direction.x +
            " y=" + direction.y + " z=" + direction.z;
    }

}