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Re: splines ???

On Wed, 5 Nov 1997, Stephen Chenney wrote:
> Subject: Re: splines ???
> > Hi,
> > we plan to model a roller coaster in VRML.
> > 
> > 1. Does anybody know if there are splines in VRML?
> > 
> > 2. If not, does anybody have an idea how to model the rail?
> We're planning a similar thing (actually, the same thing).
> I see three options:
> - Use an off-line process to generate a mesh.
> - Use an extrusion
> - Use a java program to create the geometry on the fly
>   (reduces download, but prevents some optimization by the browser).

FYI, I have implemented Non-Uniform Rational B-Splines
PROTOtypes using Java in the Script node.  This is
available from http://www.ocnus.com/NURBS/

Source code is included, so you can modify it to fit
your needs if necessary.  Send me suggestions for
added functionality.

This does reduce download time, since the mesh
is generated programatically.  The way I have
implemented it *does* allow the browser to perform
optimizations (I believe) since the resultant
mesh is just another IndexedLineSet/IndexedFaceSet.
And of course you should be able to modify the
shape of the spline and degree of tessellation at
run-time, although in practice this is prohibitively
expensive in terms of CPU to do very often.

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