[metapost] Re: Intersections of NURBs

[Laurence Finston]

On Sun, 30 Jan 2005, Larry Siebenmann wrote:

> The decomposition of projective linear transformations of the plane
> into perspectivities in R^3 is discussed in most texts on synthetic
> projective geometry.
>

Thanks.  As usual, I'll have to keep studying in order to understand your
answer.

> PS.  Chatting about de Castaljau for NURBS has
> convinced me that the de Casteljau convex hull property
> carries over reasonably well to at least those NURBS
> that are projective transforms of bezier paths.
> The key fact is (with notations from yesterday):
>
> Lets hope I am not being too optimistic...
>

At any rate, my sources on 3D graphics all indicate that NURBs are the
de facto standard for 3D applications.  So far, I've had to take this on
faith.

Thanks again for all your help.

Laurence