On Fri, 31 Mar 2000 16:32:11 -0800, ryan constantine
<rco### [at] yahoocom> wrote:

> before i ask my question, let me see if i have something straight: 
> height fields are converted into meshes, right?

More or less. Yes, they are converted to meshes but use a hf-specific
hierarchical bounding scheme to speed them up.

> now, if this is so, what happens to the ends and the bottom?  are 
> they closed off to get a closed volume?  i'm hoping they are.  

Sorry, they are not. The bottom remains open.

> and if they are, can they be used in CSG operations?  

Regardless, they can be used in CSG operations. There is a demo scene
in the standard distro called "hfclip.pov", I suggest you check it
out.

> that is the question i really want to know.  i'm
> thinking it would be cool to take one height field of a landscape, and
>another of the opposite of a horizontal cave system, and them subtract
>the caves from the landscape.  or... if one could subtract various
>shapes from a height field (like cylinders or cubes) to get caves that
>way.  can it be done?

Frankly, yes, but you have to be careful with that horizontal hf. The
'volume' of the height_field lies below it, so if you make a hf you
want to use as a cutting object, make sure you point its bottom at the
object you're cutting from.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] usanet
TAG      e-mail : pet### [at] tagpovrayorg

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