[ab] Bug in sdl:draw-pixel-* and sdl:read-pixel-*

[Michael Ben-Yosef]

Luke Crook wrote:
> If you are using the sdl_gfx library then you may as well use the functions in 
> lispbuilder-sdl-gfx as these functions will always be more efficient than the 
> Lisp native functions in lispbuilder-sdl. However, 90% of the functions in 
> SDL_gfx have lispbuilder-sdl equivalents.
> 
> What functions in sdl-gfx are you using?

At the moment, I'm only using sdl-gfx:draw-pixel-*. I'll be needing to 
draw some strings soon, and I will probably also use the roto-zoomer.

As you know, sdl-gfx:draw-aa-polygon gives anti-aliased polygons and 
sdl-gfx:draw-filled-polygon gives filled polygons; but I need polygons 
which are both filled and anti-aliased. :-) Hence I'm using the cl-aa 
package from cl-vectors. Now I see that the ASDF system called 
"lispbuilder-sdl-cl-vectors" provides a function, image-put-pixel, which 
can be used to get a "callback" put-pixel function for cl-aa. (I was 
just using my own callback wrapped around sdl-gfx:draw-pixel-*.) Anyway, 
I'm starting to just think out loud here.

Thanks for your help!

Michael