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transparency in SDL

Engines and Middleware Programming

Started by sand_man July 09, 2004 11:17 AM

3 comments, last by sand_man 19 years, 12 months ago

sand_man

100

Author

July 09, 2004 11:17 AM

i have a small bitmap image, 29x29, of a circle ball. i want to know how to make the area outside the ball transparent so you cant see it when moving across the differrent colored background. any help at all is greatly appreciated

T1mb0

134

July 09, 2004 12:34 PM

Paint the background of the image in a specific color (e.g. magenta) and

ball_surface = SDL_LoadBMP("ball.bmp");SDL_SetColorKey( ball_surface, SDL_SRCCOLORKEY, 0x00ff00ff );

should work (0x00ff00ff is the color that will not be drawn).

Clueless

185

July 09, 2004 12:46 PM

Or use SDL_image and save your images as png files with alpha channel.
http://www.libsdl.org/projects/SDL_image/

Writing errors since 10/25/2003 2:25:56 AM

Spudder

385

July 09, 2004 03:22 PM

Here's an easier way:

SDL_Surface *Foo = SDL_LoadBMP("Foo.bmp");
SDL_SetColorKey(Foo, SDL_SRCCOLORKEY, SDL_MapRGB(Foo->format, Red, Green, Blue));

where you replace Red, Green and Blue with the appropiate RGB value of the transparent pixel in the image.