It’s old news that enabling full screen anti aliasing will produce better looking result on the screen. And why is that? Well, mainly because of the subsampling technique. In essence FSAA 8x can be thought of as rendering in 8x resolution and scaling it back to 1:1 before displaying on screen.

Look at the building below.

The image was produced in 300x300 with no aliasing enabled. This result in irregular and unwanted effects in the top of the building (notice how the windows interfer and generate circular effects).

Instead, we should render our image in a much higher resolution.

And scale it back to 300x300 resolution while paying respects to nearby pixels.

However, it’s not the easiest thing to find documentation on from SDL. Sooooo… I’ve I did som digging and found the attributes SDL_GL_MULTISAMPLEBUFFERS and SDL_GL_MULTISAMPLESAMPLES. The first one is a boolean where you either enable or disable FSAA whereas the second attribute denotes the number of pixels subsampled per displayed pixel.

To setup FSAA 8x simple paste the following lines after your call to SDL_Init and right before the SDL_SetVideoMode.

SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 8);

In case you are wondering about the nitty details - you could go read this wikipedia document.