Originally Posted by AaronP
Sorry, you're right; I was thinking of EXT_swap_control, not SGI_swap_control.
Yeah and that's the exact specs ambiguity I've been mentioning. SGI_swap_control defaults swap_interval to be 1 and directly forbids setting it to 0. EXT_swap_control permits using 0 as swap_interval and also states that "Calling glXSwapIntervalSGI is equivalent to calling glXSwapIntervalEXT on the current drawable, if one exists". Does this "equivalent" means that when EXT_swap_control is available in OpenGL implementation glXSwapIntervalSGI should be implemented as simple forward to glXSwapIntervalEXT thus allowing 0 as a valid argument isn't clearly stated. Personally I would stick with prohibiting usage of zero as an argument to glXSwapIntervalSGI as allowing it might cause unexpected behavior in older applications that are unaware of EXT_swap_control/glXSwapIntervalEXT existence.