Re: [AD] Direct3D bug

[SiegeLord <slabode@xxxxxxxxxx>]

On 04/06/2014 08:33 PM, Trent Gamblin wrote:
> Around January 25th Paul changed the D3D code so that it doesn't call
> TestCooperativeLevel 1000 times per second. This breaks non-trivial games
> that use D3D and can lose the display frequently such as fullscreen window
> toggles. According to my reading of the documentation (this was a while
> ago), you're supposed to call TestCooperativeLevel in a loop like the code
> was doing before. As it was changed it's pointless to even call it at all. I
> don't know if it needs to be 1000 times per second but I think that was what
> seemed to work, and still does if put back. I'm going to revert the change
> until something else that works can be done.
>
> Thanks,
> Trent

It's not clear to me why the check in al_flip_display is insufficient to 
detect lost displays in those games, as it was in my testing of that 
commit. Is there a test case for this?  Neither Irrlicht or Ogre3D have 
a loop like that, and they created far more commercially successful 
games than Allegro ever has or will, with the correspondingly greater 
number of greater number of testers. Irrlicht calls that function in the 
equivalent of their flip display. Ogre3D calls it whenever there is a 
check for whether driver is lost (looks like most drawing commands 
trigger it).

The input lag generated by that function call makes the D3D driver 
unusable for some game types, and unless you're planning on fixing it in 
the near future, then we need to switch away from D3D as a default, as 
it is broken.

-SL