[ab] Rotozoom weirdness

[Tomi Neste]

Anthony Fairchild <anthonyf at blarg.net> kirjoitti Wed, 06 Dec 2006 23:41:53  
+0200:

> Hello again,
>
> I'm playing around with SDL-GFX:ROTOZOOM, using it instead of my still
> somewhat slow pure lisp surface rotating function.   I had to make a
> couple of modifications to the SDL-GFX code to get it to work.  The
> exported symbol for rotozoom is called DRAW-ROTOZOOM while this
> function does not exist anywhere (perhaps not yet implemented?).  I
> found the ROTOZOOM function and then just inserted an export entry for
> it.  Here's my new ROTATE-SURFACE function:

That looks like it might be caused by the way that rotozoom pads the  
resulting surface.
Playing with the surface colorkey/alpha properties should fix it. I don't  
remember the details right now, but in general it can be a bit tricky to  
get the desired effect from the rotozoom function.