Of course!  I did the "plane" method first and forgot that I'm dealing with
more surfaces with boxes than I am with planes.

Thanks!

Mike Williams wrote:

> Wasn't it Patrick Hagerty who wrote:
> >I'm playing with gems.  (I "wish" they were the real thing.  Just POV
> >stuff, though.)
> >
> >I'm observing some anomolous (to me) behavior.  I'm using a declaration
> >to define the gem structure.  If I use an "intersection" of box objects,
> >I get a dirty or noisy material as a result.  If I use an intersection
> >of planes, I get a very clean crystaline result.  The code and resultant
> >images are below.
>
> What's happening is that a box rotated by +45 is exactly the same as a
> box rotated by -45, so you're getting the coincident surface problem.
> See "2.4.2.5  Why are there strange dark pixels or noise on my CSG
> object?" in the documentation.
>
> If you delete three of the rotated boxes in your intersection it will be
> the same shape but without most of the speckles. The remaining speckles
> are caused by the fact that each of the rotated boxes have two faces
> that are coincident with the unrotated box. E.g. the box that's rotated
> by y*45 has the top and bottom face still in the same plane.
>
> You can fix that by making the first box have a slightly different size.
>
> #declare BrilliantJewell = intersection
> {
>    box { <-1.0001, -1.0001, -1.0001>, <1.0001, 1.0001, 1.0001> }
>    box { <-1.0, -1.0, -1.0>, <1.0, 1.0, 1.0> rotate  45*x }
>    box { <-1.0, -1.0, -1.0>, <1.0, 1.0, 1.0> rotate  45*y }
>    box { <-1.0, -1.0, -1.0>, <1.0, 1.0, 1.0> rotate  45*z }
>
> By the way: Don't post images to this newsgroup. Binary files should
> only be posted to a .binaries newsgroup.
>
> --
> Mike Williams
> Gentleman of Leisure

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