in news:slr### [at] fwicom Ron Parker wrote:

> I got this far before I had to ask "how do you do THAT?"  The
> answer is, of course, that you cannot.  

 So there is no direct way to calculate that :(
 An indirect way would be to get 'some' points on the sphere and use 
these with the inside() function, but that would only work on solid 
objects.

> The best you can do is fire
> a bunch of random rays at nearby points on the object and try to
> estimate the local curvature of the surface.

 Is the curvature enough to know whether my finger with polish cloth 
can reach a certain point?
 How about shooting rays from the intersection point, in a 
hemispherical pattern, aligned with the normal at intersection point. 
From that, I think it could be calculated if an object with a certain 
diameter can reach the point. Depending on that diameter the grey-value 
gets calulated.


Ingo

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