> Hello everyone,
>
> is there a common thing that I might have overlooked in the following problem?
> I am trying to make an image of what is called the "first brillouinzone of an
> fcc lattice". Essential I want to make an image of a closed surface that I think
> can be constructed by
> - first defining three touching polygons and make a union of them
> - making a mirrored copy of this union using the scale object-modifier
> - rotating the result four times by 90 degrees around the same axis
> - mirroring the result with respect to a different plane.
>
> However, one of the side faces I am looking for always turns out white. When I
> tried to debug this and left out some of operations above I saw that I also get
> different artifacts.
>
> An approximate image of what I am trying to make can be found for example at:
> http://www.ioffe.rssi.ru/SVA/NSM/Semicond/Append/figs/fmd11_2.gif
>
> A snippet of the source code I use to implement the 4 operations is here, the
> definitions of the points making up the polygon are given afterwards.
>
> I'd appreciate any feedback. Thanks in advance!
>
> Best,
>
> Andreas
>
Did some testing with your sample. I needed to reordinate the #declare, 
you posted them in a reversed order... Your "coc" variable is BOTH a 
scaling factor AND a shape modifier and you don't provide a starting 
value for it. It's not a good practice. I used a value of 1 in my tests.

Found a problem:
#declare irrBZSeiten3=union{
         object{irrBZSeiten2 rotate 0*rotz}
         object{irrBZSeiten2 rotate -90*rotz}
         object{irrBZSeiten2 rotate 180*rotz}
         object{irrBZSeiten2 rotate -90*rotz}// two identical rotate
};
Change one of the rotate -90*rotz as rotate 90*rotz


I don't see any white face, both with the 2 coincident elements or after 
having corrected that error. I even rotated your object in several ways 
without showing your isue.

You don't provide the texture you used. Maybe it have some specular 
highlight or reflection that could make a face white...
Also, if the elements are individualy textured, the coincident ones can 
cause some problem.




Alain

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