[SDL] Double buffering in windowed and fullscreen modes

Kylotan kylotan at kylotan.eidosnet.co.uk
Thu Aug 30 17:59:02 PDT 2001

> When I do doublebuffering in SDL_FULLSCREEN, SDL_Flip() takes no time
> whatsoever.  In windowed mode, however, it takes 12-20ms, as measured
> SDL_GetTicks().  What causes this slowdown?

In fullscreen mode, SDL can just tell the videocard to read from the
other screen buffer. So it's just a case of changing a pointer or two.
In windowed mode, a flip probably has to copy the data from the back
buffer to the relevant part of the main video memory, so this would be
somewhat similar to the speed of a Blit.

Ben Sizer

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