[Mesa-dev] Stream output

[Roland Scheidegger]

On 07.06.2010 21:21, Marek Olšák wrote:
>  On Mon, Jun 7, 2010 at 8:53 PM, Corbin Simpson
> <mostawesomedude at gmail.com <mailto:mostawesomedude at gmail.com>> wrote:
> 
>     This is for vert feedback, not render-to-VBO, correct? Do we have a
>     list of HW that can do it? Is there a trivial way to emulate this on
>     older HW, or should those chipsets just use Draw?
> 
> 
> gallium-stream-output == StreamOut in Direct3D 10 ==
> render-to-vertex-buffer == vert feedback to a vertex buffer == Transform
> feedback in OpenGL.
> 
> r300 could do it with some limitations since ATI has implemented
> something similar in Direct3D 9.

No render-to-vertex-buffer is quite different, as this one uses data
output from the "normal" rendering path (after rop), but transform
feedback (streamout) outputs data even before the pixel shader is run.
In theory, just about any chip could do render-to-vertex-buffer, as long
as it has at least one format which is compatible to both rop output and
vertex shader input.
But only chips supporting DX10 typically can really export data after
geometry shader stage.
It doesn't look to me like any kind of emulation is really feasible nor
desirable.

Roland