[comp.sys.mac.hypercard] Supercard: Grouping polygons under script

GFX@psuvm.psu.edu (03/29/90)

I have a card displaying several contiguous polygons, and I would like
to give the opportunity to the user to create groups as he sees fit.
In superEdit, that would involve something like choosing the draw polygon
tool, shift-selecting the polygons and Grouping them.   Problem is that
neither group nor autoTrace are available in SuperTalk.

Under script, I could collect the points as the user clicks on the polygons
he wants to fuse, and create a new polygon whose points would map
the joint outline.  However (stupid me) I can't come up with an algorithm
that will compute the points of the outline of the new polygon when it is
given the set of initial points.  Any idea? (note that the initial polygons
are arbitrarily shaped).  Thanks.  Stephane

(btw, I posted a question wrt limit of draw objects on an SC card.  Tech
support said 300 - 400.  Not clear why.  I can draw a much larger number
of polygons without any problem, but the card is irremediably garbled if
it is saved with more than a few hundreds of objects.)