In article <Xns### [at] povrayorg>,
 ingo <ing### [at] tagpovrayorg> wrote:

> Just for my understanding; Everytime I see a statement simular to this I 
> wonder, does it mean building a CSG from POV-Ray primitives and then 
> tesselate it, or tesselate the "POV-Ray primitives" to a certain level and 
> then do the CSG (as I saw it in a very old version of 3D-studio)?

It generally refers to doing CSG with meshes. Making sure you don't end 
up with gaps or odd seams where the formerly separate meshes touch is 
not an easy problem to solve. Unions are easy, but merge, difference, 
and intersection are not.

There are algorithms for tessellating arbitrary objects, but they are 
never optimal. You end up with huge amounts of triangles in places where 
you don't need them, and you can still lose small details, the point of 
a cone or edges of a box for example. You can tessellate a box with 12 
triangles, but with one of these algorithms you are likely to end up 
with hundreds of thousands just to get rid of the faceting artifacts. 
CSG of multiple meshes is really the best way to go, it's just really 
hard.

One possible compromise would be to just avoid the problem of joining 
the seams by using solid geometry CSG on the meshes, like what POV does 
now with other primitives and meshes with an inside_vector specified. 
This is not really the best possible solution, but could give some 
improvements.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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