Compositing GL

[Roderick Colenbrander]

On Wednesday 22 August 2007 20:57, H. Verbeet wrote:
> > This solution is the best way to go. Luckily Microsoft made similar
> > changes in Vista.
>
> Conceptually its probably correct, but I think the speed hit is pretty
> large, and it's not like we've got a lot of performance to spare. As
> for the Vista comparison... Vista isn't exactly well known for it's
> OpenGL performance either. What is the performance hit for something
> like the CSS stress test? That should be a bit more representative
> than dx9 swapchains.
>
> I'm certainly not saying it's not a good idea, but I do think the
> performance hit shouldn't be quite as noticeable.

There are two distinct cases. You have programs that use a toplevel for GL/D3D 
rendering (in general this is the case for games). Further you 
have 'windowed' programs e.g. programs that mix GL/D3D with a GDI gui. The 
use of GL Composition is limited to these 'windowed' programs. So the 
performance hit is also only limited to those programs. In my case the hit in 
the dx9 swap chains and the dx8 dolphin demo is about 1/3th but still there's 
a hit. As I said before in cpu limited cases I don't expect problems.

Roderick