In article <slr### [at] fwicom>, ron### [at] povrayorg 
wrote:

> Yes, it does take the caps into account.  You find the distance to 
> each face, including the two caps, using the method described, then 
> find the minimum.  None of what I described is in 2D.

Ok, I will have to take a closer look at this algorithm...


> You can remove some of the areas of concern by making a proximity 
> function that returns negative values for points on the inside of the 
> shape, but you can't remove them all.

One way to flip the inner function's sign would be to use an object 
pattern, though I may add this capability to the pattern itself.
And wouldn't this remove *all* the areas which are causing trouble with 
the object pattern? There are still other areas, but this would remove 
the problem at the surface of the proximity object, which is where the 
discontinuity is with the object pattern.


> This problem is not unique to prisms and meshes, either.  The proximity
> function is undifferentiable at the center of a sphere, too.

And the axis of a cylinder/cone, and a circle along the major radius of 
a torus, I think...actually, I think all objects generated from a 
proximity function would have this problem, fortunately, it doesn't 
always appear. Isn't the maximum gradient used to help prevent missing 
these intersections?

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

Post a reply to this message