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ANN: Chess III Arena 0.5
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Date: 2007-07-05 (07:45)
From: Daniel_Bünzli <daniel.buenzli@e...>
Subject: Re: [Caml-list] ANN: Chess III Arena 0.5

Le 5 juil. 07 à 05:05, Jon Harrop a écrit :

> There's no way this optimization should slow the program down  
> unless its
> software rendered,
> Yes but the performance difference between texture objects and  
> display lists
> should be tiny compared to the difference with immediate mode,  
> which is what
> we're comparing here.

No, it can result in a slow down even if it is harwdare rendered, the  
effect of your "optimization" is implementation dependent. The  
problem is that glTexImage2d cannot be compiled efficently in a  
display list (see the bottom of this page [1] for why this is the  
case) and it may be that in the implementation of OpenGL he uses the  
cpu to gpu texture transfer is done each time the display list is  
called. In that case if your bottleneck is in the cpu to gpu transfer  
of textures, the performance advantage of retained vs immediate is  
lost. The only platform independent way of ensuring that cpu to gpu  
texture transfers are not performed each time the display list is  
called is to use texture objects.