The reason I had these nurbs questions is that I have some problems with
bicubic patches, and wanted to know if it could possible have something to
do with the differences between nurbs and bicubic patches.

My actual problem is this: I need to model smooth shapes with relative
complicated topology. As far as I have understood bicubic patches always
have four corners and they can only be matched up four corners at a time if
the surface needs to be smooth. This means they can't be used for smooth
surfaces with complicated topology.

I have been wondering how the problem is usually handled. When looking at
wireframes made with nurbs I notice that there's almost always a few vital
patches with three or five corners. And the surface is still completely
smooth. Is that a special ability nurbs have or what...?

Anyway, any ideas how I can solve my problem? Would it work to create a
triangular bicubic patch by using a regular bicubic patch where one half is
transparent? I mean, would I get a smooth surface if I filled in such a half
patch between regular patches with four corners? In other words, do the
spline between 4 diagonal points behave the same way as the spline between 4
edge points?

I hope there's a solution out there.

Rune
--
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