[racket] Racket/gui : How to rotate a bitmap% ?

From: Jay McCarthy (jay.mccarthy at gmail.com)
Date: Mon May 9 10:21:49 EDT 2011

And that's the exact same thing you do in OpenGL too. My gl2d code
just packages those GL commands in a nice way. I have a new experiment
with doing the same thing but with a functional packaging:


Look at the contracts at the bottom. (This package, btw, can very
easily get very high frame rates with very naive rendering, because it
automatically compiles common draw sequences to the card.)


2011/5/9 Noel Welsh <noelwelsh at gmail.com>:
> 2011/5/9 Jyu 。 <julien-0659 at hotmail.fr>:
>> I can rotate a bitmap% around the (0,0) coordinate point, but I cannot do
>> the same for any other point..
> You probably need to call translate and then rotate. There is a
> transformation matrix maintained by the dc% which allows for rotation,
> translation, and scaling. If you first translate and then rotate you
> should be able to rotate your bitmap around an arbitrary point. (I say
> "should" because I haven't tested it myself.)
> HTH,
> N.
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Jay McCarthy <jay at cs.byu.edu>
Assistant Professor / Brigham Young University

"The glory of God is Intelligence" - D&C 93

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