//    The following Applet demonstrates a simple ray tracer with a
//    mouse-based painting interface for the impatient and Mac owners
public class RayTrace extends Applet implements Runnable {
    final static int CHUNKSIZE = 100;
    Image screen;
    Graphics gc;        // for screen
    Vector objectList;
    Vector lightList;
    Surface currentSurface;

    Vector3D eye, lookat, up;
    Vector3D Du, Dv, Vp;
    float fov;

    Color background;

    int width, height;