From: Dan Luecking <luecking@uark.edu>
To: Troy Henderson <thenders@gmail.com>
Cc: mailing list for ConTeXt users <ntg-context@ntg.nl>,
MetaPost List <metapost@tug.org>
Subject: Re: [NTG-context] MetaPost transformation
Date: Wed, 30 May 2012 21:37:51 -0500 [thread overview]
Message-ID: <201205310237.q4V2bpps018883@comp.uark.edu> (raw)
In-Reply-To: <CAFP+xFJmoZ0PBWK=91SY7jPmEa_4gWGSBHfnt6S659jEiQCbAg@mail.g mail.com>
At 07:56 PM 5/30/2012, Troy Henderson wrote:
>Well then in case anyone needs such a transformation, I've
>constructed the (non-unique) transformation T
>
> > t:=angle(f,e);
> > q:=e++f;
> > p:=(c*f-d*e)/q;
> > s:=(c*e+d*f)/(q**2);
> > transform T;
> > T:=identity rotated t xscaled p yscaled q slanted s shifted (a,b);
>
>This yields T=(a,b,c,d,e,f).
You can implement something like what you wanted directly
because, just as you can write equations for the parts of
a pair, you can also write equations for the parts of a
transform:
vardef mktransform (expr a,b,c,d,e,f) =
save T_; transform T_;
xpart T_ = a;
ypart T_ = b;
xxpart T_ = c;
xypart T_ = d;
yxpart T_ = e;
yypart T_ = f;
T_
enddef;
After this
transform T;
T := mktransform (1,2,3,4,5,6);
show T;
produces:
>> (1,2,3,4,5,6)
Regards,
Dan
Daniel H. Luecking
Department of Mathematical Sciences
Fayetteville, Arkansas
http://www-cs-faculty.stanford.edu/~knuth/iaq.html
--
http://tug.org/metapost/
next prev parent reply other threads:[~2012-05-31 2:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-30 21:10 Troy Henderson
2012-05-30 21:30 ` Hans Hagen
2012-05-31 0:56 ` Troy Henderson
[not found] ` <CAFP+xFJmoZ0PBWK=91SY7jPmEa_4gWGSBHfnt6S659jEiQCbAg@mail.g mail.com>
2012-05-31 2:37 ` Dan Luecking [this message]
2012-05-31 3:44 ` [metapost] " Troy Henderson
2012-05-31 7:00 ` Albrecht Kauffmann
2012-05-31 12:31 ` Troy Henderson
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