Path: dime!nic.umass.edu!caen!uunet!dtix!mimsy!folta
   From: folta@cs.umd.edu (Wayne Folta)
   Newsgroups: comp.sys.mac.apps
   Date: 19 Aug 92 03:13:46 GMT
   References: <1992Aug14.170306.17501@njitgw.njit.edu> <59728@mimsy.umd.edu> <LEE.92Aug17230143@snoopy.cs.umass.edu>
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   Organization: U of Maryland, Dept. of Computer Science, Coll. Pk., MD 20742
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   "Finally, the original poster stated in his review that Infini-D 2.0 is not a
   "spline-based modeler.  While this is true in the strictest sense (shapes are
   "not represented internally as splines by Infini-D), version 2.0 can use splines
   "(bezier curves, in particular) to create 3D models, either by importing them
   "as Illustrator or FreeHand format EPS, or by subscribing to them directly from

   I just got my ID 2.0 upgrade tonight, and immediately saw this possibility.
   Could you share what ID does internally with the splines that come in? (I.e.,
   it must break the path up into segments, but how fine?)

We use a recursive algorithm to continue breaking a curve into line segments
until each segment is of a specified "flatness."  You can see exactly how this
works by importing a curve and then double-clicking on it in the workshop to
see the points it was broken into.  Although it's possible to change the
magical flatness value in the code, there's no user-specifiable way to do it
in the current application.  We thought about making it an option, but it
starts to get a little hairy (do you set it separately for each object?  If
not, what does it mean if it changes and there are subscriptions in the scene?
Do those objects suddenly change their "facetedness" the next time the
publisher is updated?).  If this is the sort of parameter you'd like to have
control over, we'd love to hear how you would want to use it...

   At first glance, ID does almost everything my wishlist included!
   Congratulations! Your integration of System 7 features is particularly nice.
   I also like the fact that you don't have to go to raytracing for shadows, so
   you can use shadows and environment maps (even animated) as a real alternative
   to raytracing. The manual is also very nice (I think the surface map
   illustrations using the readily-available world PICT is a nice touch, for
   example). Using Illustrator to fine-tune manipulate lathes/extrusions will be
   super-nice, too! (I agree that, with System 7, this is a superior alternative
   to improving your own workshop. Would be nice to internally support Beziers,
   though--I think.)
Thanks for the kind words, I'll pass them along!

   (While I have you on the line, the three things I would yet like to see are:
   RIB output, Constructive Solid Geometry, and scripting. The latter mainly to
   turn data into simultaion/animation.)
I can't promise anything, but all three are options we've considered or are
considering for future products or future versions of Infini-D.  That doesn't
mean that you'll seen them soon, or at all, necessarily, but they're all
strong possibilities...  (a fine example of weasel-speak, if I do say so
myself! :-))

   -- 


   Wayne Folta          (folta@cs.umd.edu  128.8.128.8)
--
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