In article <40a593f3@news.povray.org>, "Xiaobin Wu" <xwu### [at] ciseufledu> 
wrote:

> "Warp" <war### [at] tagpovrayorg> wrote in message
> >   Note also that two smooth triangles might not share the same normal
> > vectors in their shared vertices. That is, the triangles are smooth, but
> > their common edge has a sharp change in lighting (which is often a useful
> > feature).
> 
> I have this in mind. Thanks. I called it bump mapping or artificial normals,
> which shouldn't affect the shape.

I don't think you quite understood. For example, think of a deformed 
box. It has edges that should not be smoothed out, but which are actual 
geometry, not faked by tweaking the normals.


> I remember one of the nicest example is a coin modeled by a simple
> cylinder but with artificial normals on its sides. Since its sihouette is
> always from the cylinder, you can never tell its sides are actually flat!

I'm not sure what this has to do with subdivision...normal perturbation 
in POV is specified as part of the texture. Some objects will return 
"false" normals...smooth triangles, smoothed height fields, etc.

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