Trevor G Quayle wrote:
> 
> POV doesn't need to think to 'drop' zero volume spheres and boxes.  They
> have no diminesional surface for rays to intersect so they can be left in
> the scene as is without causing parsing problems, the individual rays will
> pass by them unhindered without POV having to alter the scene.  This is not
> the case for cylinders, POV would need to be able to think to see that a
> cylinder is degenerate and remove it because of the problem with them as
> its been explained.   This additional thinking by POV may add to the
> parsing overhead.
> 

This sounds as if the POV parser is in bad need for a
garbage filter. Imagine a typo in a macro produces
boxes with no volume. Actually I tried it and the
only message I got was that there was no pigment given.
With given pigment I could blow up parsing time at will.

#declare c=0;
#while(c<100000)
   box{<0,0,0><0,0,0> pigment {rgb <1,0,0>}}
   #declare c=c+1;
#end

even replies:
Slab Building Error: Out of memory.  Cannot allocate -124288 bytes for 
temporary tree entry.

It shouldn't be too hard to check a box size or a
cylinder length while parsing. Probably it's that
nobody had enough spare time to implement this.

Sebastian

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