Re: LZ: Rotation...

To: list-zshell@lists.ticalc.org
Subject: Re: LZ: Rotation...
From: sarlok@juno.com (Jonathan L Anderson)
Date: Tue, 17 Jun 1997 11:45:16 EDT
References: <Pine.SOL.3.96.970616193742.9237A-100000@vertex.ucls.uchicago.edu>
Reply-To: list-zshell@lists.ticalc.org


On Sun, 15 Jun 1997, Buddy Smith wrote:
> 
> 
> Does anyone know how to rotate a sprite on the screen (w/out USGARD, 
>in case you are wondering...)  I need to turn a simple 15x15 sprite 
>around sideways.  I'm not really quite sure how to do sin/cos 
>rotations (I have no idea how sin/cos even can do rotations) but if 
>someone can help it will be greatly appreciated
> 
> Buddy Smith
> ti85calc@bellsouth.net

I'm not sure how to do it in Z80 asm, but basic rotation is like this:

  newx = x*cos(angle) - y*sin(angle)
  newy = y*cos(angle) + x*sin(angle)

Keep in mind that this rotates counter-clockwise around the origin, so
you would probably want to make the origin be in the middle of the
sprite.

Jonathan Anderson
sarlok@juno.com

References:

Re: LZ: Rotation...

From: Will Stokes <wstokes@vertex.ucls.uchicago.edu>