"joost_1972" <joo### [at] hotmailcom> wrote in message 
news:web.499eaafe5952c0ab2a36ae330@news.povray.org...
>
> First, I've made a generic macro to create different kinds of roofs for 
> houses
> with round edges. Now I get a loads of degenerate triangles messages 
> (please
> remove...). Is this a problem? And why does povray simply not render a
> degenerate triangle, while a degenerate cylinder causes an error and stop 
> in
> rendering altogether?
>

This simply means that two or more points on those triangles are in the same 
place (or very close together). If you're generating the triangles, then you 
could add logic into your macro to avoid or suppress degenerate triangles, 
but I don't think they're a serious problem, so you could just live with the 
messages. I think it's just warning messages and that POV-Ray simply renders 
the scene without those 'invisible' triangles.

I'm only guessing why the behaviour is different for degenerate triangles 
and cylinders, but:
Maybe the logic behind causing degenerate cylinders to stop the render is 
because it could be difficult to determine what to show in the scene. 
Degenerate triangles are invisible points or lines. If the end points of a 
cylinder are the same, but it has a non-zero radius, would you show two 
coincident disks or nothing at all? Alternatively, maybe the logic is that 
degenerate cylinders are usually easy to find and fix, whereas, oftentimes 
triangular meshes are generated by other programs and the problem can be 
embedded in amongst masses of data, making it very much more difficult to 
find and fix.

Regards,
Chris B.

Post a reply to this message