Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!rice!uw-beaver!zephyr.ens.tek.com!tektronix!sequent!ccssrv!brian
From: brian@ccssrv.UUCP (Brian Lantz)
Newsgroups: comp.graphics
Subject: Question
Message-ID: <871@ccssrv.UUCP>
Date: 29 Nov 89 20:25:16 GMT
Reply-To: brian@ccssrv.UUCP (Brian Lantz)
Organization: Control-C Software, Inc., Beaverton, OR
Lines: 16


The transformation matrix:

   | cos(a)  -sin(b)    0 |
   | sin(a)   cos(b)    0 |             a != b
   |     0        0     1 |

has me mystified.  In empirical tests with lines, it rotates through
a different angle depending on the slope of the line.  I can see that
that property should be expected after having it pushed in my face,
but I still don't have an intuitive grasp of the full function of
this transform.  Can it be constructed as the product of the basic
translate, scale, and rotate transforms?  How can one summerize
its characteristics? All answers will be appreciated.

Brian


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