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From: larry@csccat.cs.com (Larry Spence)
Newsgroups: comp.graphics
Subject: Ashlar patent on "Drafting Assistant" technology?
Message-ID: <4213@csccat.cs.com>
Date: 28 Mar 91 01:41:10 GMT
Reply-To: larry@csccat.cs.com (Larry Spence)
Organization: Computer Support Corporation. Dallas,Texas
Lines: 28

Some readers may be familiar with a CAD/drawing product from Ashlar named
Vellum.  One of its main features is its so-called Drafting Assistant.
While drawing or editing in Vellum, as the cursor is moved, the program
dynamically detects proximity to intersections of other lines and curves,
midpoints of primitives, and other "likely" snap points.  The advantage is,
of course, that the user need not explicitly request the snaps, they are
determined on-the-fly and the user is notified (via a status line) what
"key" point or line he/she is near.

As I was reading through some Ashlar promotional material, I noticed that
the Drafting Assistant is "patent pending."  I can't see how this could
be granted, given that the SIGGRAPH 1986 paper

          Snap Dragging
          E.A. Bier (EECS, UC Berkeley) & M.C. Stone (Xerox PARC)
          SIGGRAPH 1986 Proceedings
          pp. 233-240

desribes a system implemented at PARC which appears to be a superset of
the Assistant.  The authors' scheme of "alignment objects" is _very_ similar
to Vellum's, right down to visible "guidelines" in a distinguished color.

Any and all info (patent #) and comments would be appreciated.  Thanx.

-- 
Larry Spence
larry@csccat.cs.com
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