Re: [Mesa3d-dev] rasterize or rendering?

[rt <rt...@um...>]

	what about specialized hardware that performs the rendering based
on a final list of vertices? how can a hardware driver deal with this
situation? do hardware drivers operate on lists of vertices?

rt

On Tue, 6 Feb 2001, Gareth Hughes wrote:

> rt wrote:
> > 
> > does PointFunc, QuadFunc, LineFunc and the like provide for
> > accelerated rasterization, or accelerated rendering, or both? it looks
> > like the 3Dfx driver acclerates the rendering - is this correct? the
> > xmesa driver, on the other hand, looks like it is concerned with
> > rasterization. if they provide for both, how does one get them to provide
> > for accelerated rendering working with a list of vertices?
> 
> I'll take a stab at this...
> 
> It kind of depends on which version of Mesa you're looking at. 
> Essentially what used to happen was core Mesa would allow a
> rasterization-level driver (one that takes a batch of primitives and can
> render them natively, like the pre-T&L hardware drivers) to hook out the
> primitive functions.  Drivers would supply functions if it could handle
> rendering with the current state.
> 
> If not, it would set them to NULL and mark the IndirectTriangles
> bitfield with DD_TRI_SW_RASTERIZE and the like.  Core Mesa would then
> plug in a software triangle function, which spits out spans that must be
> handled by the span-level interface.  For hardware drivers, the
> implementation of the span-level interface typically involves taking a
> bunch of pixels and sticking them in the framebuffer (or vice versa, for
> read functions).
> 
> In the latest, still-under-active-development Mesa code, if the driver
> hooks out the primitive functions and it can't handle the primitives
> natively, it must call the software rasterizer itself.  The same thing
> happens with the software primitive functions, they still spit out spans
> that are copyied to/from the framebuffer (typically).
> 
> This is a pretty rough overview, completely from memory (so it may be
> slightly inaccurate).  I'm a little confused by the terminology you use
> -- it's more a matter of rasterization-level versus
> dumb-framebuffer-level (or perhaps the original Voodoo Graphics)
> drivers, rather than rasterize versus render.
> 
> -- Gareth
> 
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