Second follow-up: I've got a very nice revision to SpherePortrayal3D and 
a few other classes which makes it easy to modify the attributes (color, 
size, etc.) of spheres at any time.  It's partially 
non-backward-compatable, but I think it'll be okay.  I can commit this 
if you want to play with it and then work on getting the other similar 
portrayals (cone, etc.) working nicely.  Or just do a big submit in a 
while.  Lemme know.

Sean

Joerg Hoehne wrote:
> Dear developers,
> 
> I'm trying to change the color of an SpherePortrayal3D object during runtime. I've checked my 
> code and I'm positive the color of the object will be changed but not visualized accordingly.
> 
> I've got the impression the color of a XXXPortrayal3D object can't be changed after the first 
> construction (or display) of the 3D scene by j3d. Before the first construction/display I was able to 
> change the color with the same code snipped found below.
> Here is the code snippet anyway ('this' references to a subclassed SpherePortrayal3D object):
> 
> this.appearance = SpherePortrayal3D.appearanceForColor(color);
> 
> There has been a discussion some years ago about a similar topic (changing the transparency 
> during runtime) and I wonder if a solution has been found.
> 
> I'm working on a Mac with OS X 10.6. The monitored effect might be os depended because j3d 
> might cache some information about the displayed objects and assumes some properties won't 
> change in the future.
> 
> Help!
> 
> 
> Jörg