[SDL] Best way to rotate a sprite?

Atrix Wolfe atrix2 at cox.net
Mon Jan 27 15:22:01 PST 2003


thats a neet trick

----- Original Message -----
From: "Sami Näätänen" <sami.naatanen at kolumbus.fi>
To: <sdl at libsdl.org>
Sent: Monday, January 27, 2003 3:15 PM
Subject: Re: [SDL] Best way to rotate a sprite?


> On Tuesday 28 January 2003 00:40, Tane Piper wrote:
> > On this note, I think your right, and I need to re-think it.  I was
> > thinking more 1 image which I rotate through 360-degrees, but I don't
> > really need more than 8, or 16 directions at the most. So basically
> > each time I press the left or right arrow key, it will turn the
> > graphic 22.5 degrees, and then make it travel along that vector for
> > the up/down arrow keys.  If I need to I can always make the
> > resolution of the turn smaller to make 32 or 36 directions if needed.
>
> Well 32 is better than 36, because with 32 different angles you will get
> the 45 degree diagonal angles, but with 36 steps the angles will go in
> 10 degree steps.
>
> PS. With 32 (or 16) steps you can use logical and to clamp the angle
> after increasing or decreasing it.
>
> angle = (angle + 1) & $1F; // clamps the angle between 0 and 31
> angle = (angle - 1) & $1F; // clamps the angle between 0 and 31
>
>
>
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