Improving DirectDraw OpenGL renderer for SoC?

Alexander Nicolaysen Sørnes alex at
Thu Mar 22 15:41:48 CDT 2007

Onsdag 21 mars 2007 20:32, skrev du :
> Am Mittwoch 21 März 2007 20:01 schrieb Alexander Nicolaysen Sørnes:
> > Greetings,
> >
> > i am thinking about participating in the Summer of Code, and thought it
> > would be interesting to improve DirectDraw such that Command & Conquer
> > Tiberian Sun & Red Alert 2 run faster.  Currently, they crash once the
> > mouse is moved in-game when OpenGL rendering is enabled.  Thus the
> > project would involve fixing that bug, and then other performance
> > issues/crashes that occur. However, I don't really have much experience
> > with C and Wine. The closest I have gotten is some patches for Wine's
> > WordPad
> > implementation. Would it be feasible to acquire the necessary knowledge
> > and fix the bugs before the end of summer?
> I think learning those things over the summer is feasable. There is not
> much OpenGL knowledge required, it is mostly about drawing textured quads.
> Unfortunately other issues are major:
> The crash when moving the mouse is because those games draw the mouse from
> a different thread. My multithreaded opengl patches may fix that. But for
> real thread safety we have to implement locking of private data. For one
> part this needs a lot of patience because those patches are tricky to
> review for Alexandre, and it needs knowledge about thread synchronisation.
> Overall it is a very tricky task.
> The other issue is render target locking. This is essentially something
> that is not well supported by OpenGL. There are 2 extensions which can help
> to improve that, one is the pixel buffer objects extension, the other one
> is a nvidia only extension which does exactly the same as
> IDirectDrawSurface7::Lock. If neither of those extensions is available, or
> if pbos turn out to be slow too, we can only play tricks like watching the
> application's behavior and predict the area it will modify. I have started
> toying with that, the most important fragment is this:

A pity.

What about fixing Bug #2666, about how the menu text colour is 'lost' in Age 
of Empires I & II.  I know these games are not really playable without a DIB 
engine, but they won't be properly playable either without the campaign texts 
etc.  I apologize if I seem a bit hasty, but the deadline is fast 
approaching . . . :)

Alexander N. Sørnes

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