A89: Re: Re: Rotating Sprites
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A89: Re: Re: Rotating Sprites
Thanks, this is pretty much what I was looking for.
B Clark
> Hi!
>
> | I have several ideas for some games, which require displaying a
sprite
> | at various angles. I remember something about using matrices to do this,
> but
> | I don't know how to implement this. I'm looking for a C function which
> can
> | quickly rotate a sprite at various angles. Any ideas?
>
> Depending on what you want, yes. If the angles are just 90°, 180°, and
> 270°, this is rather easy to do. 180° just involves switching rows in the
> sprite from the outside to the inside or verse vica. 90° and 270° are
more
> complicated: You'll have to test each bit and put it in its new location.
> I don't want to think about any details right now, but the fact is that
it's
> doable.
>
> All other angles involve a lot of math, especially trigonometry. For
small
> sprites, this also reduces quality a lot. Calculating new positions for
all
> pixels is really slow as well. I would recommend vectorizing your sprites
> into polygons and calculating the new points for all corners of the
> polygons. Again, this involves trig; remember that floating point
functions
> are slow. I don't want to go into any detail here; I assume you can do
the
> math.
>
> Sorry if I wasn't able to help a lot.
>
> Bye,
> Sebastian
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