Path: utzoo!utgpu!water!watmath!clyde!att!alberta!ubc-cs!uw-beaver!cornell!rochester!pt.cs.cmu.edu!sei!ajpo!eberard
From: eberard@ajpo.sei.cmu.edu (Edward Berard)
Newsgroups: comp.sys.mac.programmer
Subject: Rotation of Objects
Keywords: Rotation, Object-Oriented Graphics, Bit-Mapped Graphics, Text
Message-ID: <360@ajpo.sei.cmu.edu>
Date: 19 Aug 88 09:04:05 GMT
Lines: 41

I have a multi-part question concerning the rotation of objects on a
Macintosh: 

   a) Given an object-oriented graphic object (e.g., a rectangle or an
      oval) and a point about which it is to be rotated, what are some
      of the better algorithms for rotating this object? If there is
      more than one viable way to accomplish the rotation, what are
      the trade-offs?

   b) Given a bit-mapped graphic object (e.g., a picture or icon) and
      a point about which it is to be rotated, what are some of the
      better algorithms for rotating this object? If there is more
      than one viable way to accomplish this rotation, what are the
      trade-offs?

   c) Given a text object and a point about which it is to be rotated,
      what are some of the better algorithms for rotating this object?
      Do concepts such as font and style impact these algorithms? If
      there is more than one viable way to accomplish this rotation,
      what are the trade-offs?

   d) For each of the above, consider the user interface issues. For
      example, during rotation, should the user be presented with a
      schematic representation of the object (e.g., a dashed-line
      outline of the region occupied by the object)?

   e) Consider the impact, if any, of accomplishing the above
      rotations from a remote source. Specifically, suppose you had to
      direct the Macintosh from another computer, e.g., you are sending
      commands to the toolbox over an RS-232C line, Ethernet, or
      AppleTalk. Does this change any of your answers? What are the
      trade-offs? 

Obviously, general computer graphics rotation algorithms are available
in any number of texts. However, the intent of the above questions is
to narrow the focus to the Macintosh environment. I would also be
interested in a discussion of directing the output of the above
rotations to both Postscript and non-Postscript printers.

				-- Ed Berard
				   (301) 695-6960