@noelWelsh : I tested your advice, but it not run.. I tested to rotate and translate then : The bitmap is turn around another point..I test to translate and rotate then, the result is the same. Thanks you anyway. @Jay : I don't know how you can rotate bitmap with gl2d library.. I must draw with another thing ?
> Date: Mon, 9 May 2011 08:21:49 -0600 > Subject: Re: [racket] Racket/gui : How to rotate a bitmap% ? > From: [email protected] > To: [email protected] > CC: [email protected]; [email protected] > > 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: > > https://github.com/get-bonus/get-bonus/blob/master/exp/gl.rkt > > 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.) > > Jay > > 2011/5/9 Noel Welsh <[email protected]>: > > 2011/5/9 Jyu 。 <[email protected]>: > >> 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. > > > > _________________________________________________ > > For list-related administrative tasks: > > http://lists.racket-lang.org/listinfo/users > > > > -- > Jay McCarthy <[email protected]> > Assistant Professor / Brigham Young University > http://faculty.cs.byu.edu/~jay > > "The glory of God is Intelligence" - D&C 93
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