Re: [Dri-devel] HW accel render to a texture in shared memory?

[Ian R. <id...@us...>]

Nicholas Leippe wrote:

> So, here's my odd question:
> 
> Is it possible to put the older (pci) card in the system w/the radeon, 
> have the radeon render to a texture, and have the older card simply 
> display the texture?

I don't think that you could easilly do it transparently to apps.  It 
*might* be possible to have the Radeon driver copy the back-buffer to 
the other card on a glXSwapBuffers, but that doesn't handle 
single-buffered visuals or rendering to the front-buffer.

> p.s. I realize this still doesn't resolve the 2d issue, but 2d off the 
> older card should be fine.  Kinda like the 3d pass-through that was used 
> w/the 3dfx voodoos.

The original PowerVR cards (i.e., the Matrox M3D) worked exactly like 
this.  They were a small PCI card w/4MB of texture memory.  They would 
render the scene 1 raster at a time (basically) and blit it across the 
PCI bus to the other video card.  The original PowerVR cards didn't have 
a frame-buffer or a video output at all!  Oh yeah, and they were faster 
than a 4MB Voodoo Graphics based card. ;)