"Kenneth" <kdw### [at] gmailcom> wrote:

> > HOWEVER... trying to extrapolate this to TWO dimensions (never mind THREE) has
> > turned out to be a really thorny problem. Basically, it boils down to
> > this: What part of an IRREGULARLY-shaped object should be considered as
> > the 'point' to determine its equal spacing from another object?

Ha - you seem to have taken a liking to solving this little problem.

I've been away from my work area for a week, so I haven't had much time to
dabble with any of this.

I'm thinking that this might be a situation where trace() is invaluable.

Just off the top of my head:
1. determine the center of mass coordinates of all the parts relative to the
center of the expansion.
2. determine 3 vectors for that piece for use in trace (trivially the
coordinates, interpreted as a vector, one with a negative multiplier) to get the
near and far points of the piece that are in line with the expansion direction,
and the closest point of the center of expansion piece
3. translate the piece along the direction of expansion vector, and keep the
length between the pieces a multiple of the expansion constant for that frame
4.work outwards

Not sure that the distance between ALL of the pieces would be constant - as
that's probably impossible to do - but it's a quick way to do the expansion
without having to resort to a Delaunay tetrahedralization or something along
those lines.

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