In article <3872213e@news.povray.org>, "Patrick Dugan" 
<pat### [at] usticom> wrote:

> I have trying (somewhat successfully) to "chop" heightfields.  I first 
> used
> a bounded_by statement to make the heightfield round (to cut of the 
> corners)

Don't do that, bounded_by isn't intended to do that and is unreliable. 
Use clipped_by or intersection instead.


> but then trying to remove a "chunk" from the inside is difficult.  When I
> tried using the difference statement it never works and whatever the 
> object
> is (cube for example) ends up showing up regardless of using difference 
> or
> union.  I finally tried using a difference with a cube (with a clear
> pigment) which seems to work but according to the Povray docs I shouldn't 
> be
> trying a "difference" with a heightfield.  I guess my question is are 
> there
> any "easy" ways to remove material from a hieghtfield without going to
> convoluted methods??

CSG operations leave a surface over the areas that are removed or 
created. The workarounds are to use a clear texture on the CSG object or 
to use clipped_by.
To use more than one object with clipped_by, just use a union of the 
clipping objects. The inverse keyword might be useful too.

-- 
Chris Huff
e-mail: chr### [at] yahoocom
Web page: http://chrishuff.dhs.org/

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