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POWhat is the proper way to use GFX rotozoomSurface with SDL for drawing transparent sprites?
 

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  1. POWhat is the proper way to use GFX rotozoomSurface with SDL for drawing transparent sprites?
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    <p>I'm using the latest SDL/GFX libs on Fedora 10 and I'm trying to render a PNG or GIF image onto the screen surface. I could not get transparent PNG's to display at all so I replaced the transparent parts or my sprite with all white (and tried Magenta 255,0,255). The white-transparent PNG displays fine using this code:</p> <pre><code>SDL_Surface *image = load_image("sprite-white.png"); SDL_Surface *roto = SDL_DisplayFormat(image); SDL_SetColorKey(roto, SDL_SRCCOLORKEY, SDL_MapRGB( roto-&gt;format, 255,255,255 )); SDL_BlitSurface( roto, NULL, surface, &amp;offset ); </code></pre> <p>But when I try to rotate the sprite it does not drop all the white pixels. I replace the above code with this to rotate:</p> <pre><code>SDL_Surface *image = load_image("sprite-white.png"); SDL_Surface *roto = rotozoomSurface(image, rotation_degrees, 1, 1); SDL_Surface *roto2 = SDL_DisplayFormat(roto); SDL_SetColorKey(roto2, SDL_SRCCOLORKEY, SDL_MapRGB( roto2-&gt;format, 255,255,255 )); SDL_BlitSurface( roto2, NULL, surface, &amp;offset ); </code></pre> <p>I end up with a white outline around some of the good pixels. GIF images give the same results. </p> <p>When trying with transparent PNG/GIF files the code was the same except I did not call SDL_SetColorKey. Then the PNG did not display properly at all. One strange thing I found was the transparent PNG looked the same in MS Paint as it did in SDL, but GIMP/Photoshop programs opened it correctly. </p> <p>Is there something I'm missing setting up the destination surface?</p> <p>Google did not turn up much, a working example would be great. </p>
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