Not So Simple Ray Tracing
ray tracing + phong shading + shadows + reflection + refraction
Mouse drag rotates spheres (camera style, i.e. inversed direction).
Mouse drag while holding shift: the same but the refraction ball 'stays'.
Up/Down key increases/decreases focal length.
Right/Left key increases/decreased the drawn size.
'd' changes different dragging styles.
Trick: hold the mouse button before/while pressing any keys to get a preview of what you are doing.
To see the refraction working, bring the lonely whitish ball in front (and try mouse drag while holding shift).
Cool images, e.g. this one, could be achieved by changing
the focal length to get close to the central sphere and then go large size... but be patient for a few seconds
As always, some browsers need an extra click on the applet initially in order to do things with it.
more features available in ver2