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Re: BafflinTransform

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In article <fder68l1c0etqevoaigdb3f09l4rp222l1@4ax.com>,
 Gene Wirchenko <genew@ocis.net> wrote:

> On Thu, 4 Oct 2012 07:22:30 -0700 (PDT), bob smith
> <bob@coolfone.comze.com> wrote:
> 
> [snip]
> 
> > It seems like when I want to "tack on" an operation, it is 
> > actually a preConcatenate.
> >
> > This is counterintuitive to me.
> >
> > Also, when you are just doing commutative operations,
> > like just translation, it doesn't matter whether you 
> > preConcatenate or concatenate.
> 
>      Matrix multiplication is NOT commutative.
> 
> [snip]

Absolutely correct, as well as pithy. Conceptually, it may help 
to think of a series of (post-) concatenated transformations as 
having been applied in a last-specified-first-applied order. In 
the example cited below, a small, U-shaped Polygon is centered 
about the origin. The following transform rotates, scales and 
translates the Polygon in the (apparent) reverse of program 
order:

    AffineTransform at = new AffineTransform();
    at.translate(SIZE/2, SIZE/2);
    at.scale(60, 60);
    at.rotate(Math.PI/4);

<https://sites.google.com/site/drjohnbmatthews/point-in-polygon>

-- 
John B. Matthews
trashgod at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>

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BafflinTransform bob smith <bob@coolfone.comze.com> - 2012-10-03 07:58 -0700
  Re: BafflinTransform markspace <-@.> - 2012-10-03 08:45 -0700
    Re: BafflinTransform Lew <lewbloch@gmail.com> - 2012-10-03 10:41 -0700
      Re: BafflinTransform Gene Wirchenko <genew@ocis.net> - 2012-10-03 10:51 -0700
      Re: BafflinTransform Arne Vajhøj <arne@vajhoej.dk> - 2012-10-03 21:36 -0400
        Re: BafflinTransform Gene Wirchenko <genew@ocis.net> - 2012-10-03 21:49 -0700
        Re: BafflinTransform Jeff Higgins <jeff@invalid.invalid> - 2012-10-04 03:26 -0400
          Re: BafflinTransform Gene Wirchenko <genew@ocis.net> - 2012-10-04 09:30 -0700
          Re: BafflinTransform Arne Vajhøj <arne@vajhoej.dk> - 2012-10-04 17:38 -0400
            Re: BafflinTransform Jeff Higgins <jeff@invalid.invalid> - 2012-10-05 03:00 -0400
              Re: BafflinTransform Arne Vajhøj <arne@vajhoej.dk> - 2012-10-05 22:02 -0400
        Re: BafflinTransform Lew <lewbloch@gmail.com> - 2012-10-04 12:05 -0700
    Re: BafflinTransform bob smith <bob@coolfone.comze.com> - 2012-10-04 07:22 -0700
      Re: BafflinTransform Gene Wirchenko <genew@ocis.net> - 2012-10-04 09:35 -0700
        Re: BafflinTransform "John B. Matthews" <nospam@nospam.invalid> - 2012-10-04 13:58 -0400
          Re: BafflinTransform markspace <-@.> - 2012-10-04 11:44 -0700
            Re: BafflinTransform "John B. Matthews" <nospam@nospam.invalid> - 2012-10-04 21:23 -0400
              Re: BafflinTransform markspace <-@.> - 2012-10-04 19:27 -0700
                Re: BafflinTransform Peter Duniho <NpOeStPeAdM@NnOwSlPiAnMk.com> - 2012-10-04 19:55 -0700
                Re: BafflinTransform Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-10-04 23:33 -0400
            Re: BafflinTransform Gene Wirchenko <genew@ocis.net> - 2012-10-05 09:04 -0700
              Re: BafflinTransform markspace <-@.> - 2012-10-05 09:34 -0700
                Re: BafflinTransform Gene Wirchenko <genew@ocis.net> - 2012-10-05 12:58 -0700
                Re: BafflinTransform markspace <-@.> - 2012-10-05 17:15 -0700
          Re: BafflinTransform Gene Wirchenko <genew@ocis.net> - 2012-10-04 13:51 -0700
  Re: BafflinTransform Jeff Higgins <jeff@invalid.invalid> - 2012-10-03 15:15 -0400
    Re: BafflinTransform Lew <lewbloch@gmail.com> - 2012-10-03 12:49 -0700
  Re: BafflinTransform Roedy Green <see_website@mindprod.com.invalid> - 2012-10-03 16:01 -0700

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