[Mesa-dev] [PATCH] gallium: add bits for clipping points as tris (d3d-style)

[Lauri Kasanen]

On Fri, 10 Jan 2014 03:57:45 +0100
sroland at vmware.com wrote:

> From: Roland Scheidegger <sroland at vmware.com>
> 
> OpenGL does whole-point clipping, that is a large point is either fully
> clipped or fully unclipped (the latter means it may extend beyond the
> viewport as long as the center is inside the viewport). d3d9 (d3d10 has
> no large points) however requires points to be clipped after they are
> expanded to a rectangle. (Note some IHVs are known to ignore GL rules at
> least with some hw/drivers.)
>
> Hence add a rasterizer bit indicating which way points should be clipped
> (some drivers probably will always ignore this), and add the draw interaction
> this requires. Drivers wanting to support this and using draw must support
> large points on their own as draw doesn't implement vp clipping on the
> expanded points (it potentially could but the complexity doesn't seem
> warranted), and the driver needs to do viewport scissoring on such points.

Is there any possibility of this being exposed to user-space? With that
hat on, it would have been useful to me several times in the past.

Perhaps whoever was Mesa's ARB contact could propose an extension? I
know nothing about how that happens, just would like this functionality.

- Lauri