RE: [Visualpython-users] Changing the lighting in vpythonB

[David S. <da...@vi...>]

> One of the reasons I wanted to get into Vpython was to make 
> astronomical demos (parallax, phases of the moon, etc).  To 
> get phases in the solar system right, you need to have the 
> light source at the center (the sun). Also, the sun shouldn't 
> have a dark side.  Is there any way to tell Visual that the 
> source of light is at the origin (or some other point in the 
> space?).  So far, I've only been able to change the direction 
> and intensity 
> of the lighting, not it's source position (it seems to come 
> from off-screen).

Sorry, but no.  Visual's lighting calculations currently assume a
constant direction for each light (as opposed to a constant position).

> If not, is there a way to have an object "ignore" the 
> lighting (so that it 
> doesn't have a dark side)?  That way, I could try to fake out 
> central lighting by continuously updating the lighting 
> direction to be from behind the sun (but then the sun is 
> dark).  Not perfect, but a step in the right direction.

You may be able to approximate this behavior by setting the color of the
sun to something like (100,100,100).  This is not really supported by
Visual by design, but I believe the current implementation happens to
give this behavior in all cases.

Dave