On Sat, Nov 30, 2002 at 08:04:55PM +0100, Felix Kühling wrote:
> On Sat, 30 Nov 2002 17:20:04 +0100
> Felix Kühling <[EMAIL PROTECTED]> wrote:
> > I see the problem. On many state changes, a corresponding driver
> > function is called. In a parallel pipeline implementation, if there is
> > still vertex data (with associated state) pending in the pipeline, it
> > will be rendered by the driver with the wrong state. A proper solution
> > would be to call the state-changing driver functions (or only
> > UpdateState?) from within the pipeline, just before a driver stage is
> > run. The required amount of modifications to mesas driver state
> > management seems not too big. A quick recursive grep in
> > xc/xc/extras/Mesa for "ctx->Driver\.[[:alnum:]]*[[:space:]]*(" finds 63
> > lines in 23 files.
>
> Vertex formats are the real problem. Driver functions are called
> directly from the GL application and modify the driver state bypassing
> the pipeline.
Could you please give an example?
> Would it be worth sacrificing for a multi-threaded pipeline on an SMP
> system? In the radeon driver vtxfmt seems to be only enabled with TCL.
> But I remember some mails about vertex formats and the mach64 driver.
> Are vertex formats widely used with non-TCL drivers?
All drivers have a vertex format. One of the last stages of the Mesa
pipeline on a DRI driver is to build vertex buffers, which are nothing
more than a big array of vertices using that vertex format. What happens
is that most drivers use the D3D vertex format. While in newer cards
that format usually corresponds to the card native vertex format, on
older cards (such as Mach64, and 3DFX) it doesn't.
In summary, the vertex format it's like a C structure of how the card
expects to see a vertex when reading the system memory by DMA.
Now, returning to the main issue here, I'm not seeing what state changes
happen during the vertex buffer construction... besides the vertex
buffer itself, which would had to be thread specific.
José Fonseca
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