Mesa (gallium-fb-dimensions): gallium: doc tweaks for bypass_vs_clip_and_viewport

[Brian Paul]

Keith Whitwell wrote:
> Module: Mesa
> Branch: gallium-fb-dimensions
> Commit: 609b043d442c99e48d5310244e648ea8a6cc2e8a
> URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=609b043d442c99e48d5310244e648ea8a6cc2e8a
> 
> Author: Keith Whitwell <keithw at vmware.com>
> Date:   Mon Jan 11 11:03:44 2010 +0000
> 
> gallium: doc tweaks for bypass_vs_clip_and_viewport
> 
> ---
> 
>  src/gallium/docs/source/cso/rasterizer.rst |   10 +++++++---
>  1 files changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/src/gallium/docs/source/cso/rasterizer.rst b/src/gallium/docs/source/cso/rasterizer.rst
> index 4d8e170..2ca9b64 100644
> --- a/src/gallium/docs/source/cso/rasterizer.rst
> +++ b/src/gallium/docs/source/cso/rasterizer.rst
> @@ -133,9 +133,13 @@ implementation-dependent, but will usually be Gourard for most hardware.
>  bypass_vs_clip_and_viewport
>  ^^^^^^^^^^^^^^^^^^^^^^^^^^^
>  
> -When set, this implies that vertices are pre-transformed for the viewport, and
> -will not be run through the vertex shader. Note that implementations may still
> -clip away vertices that are not visible.
> +When set, this implies that vertices are pre-transformed for the
> +viewport, and will not be run through the vertex shader. Note that
> +these vertices will fall outside the conventional unit-cube clip
> +space.  Implementations are expected to discard pixels which fall
> +outside the viewport (XXX: how is the viewport defined in this case),
> +and may if desired choose to subject these vertices to clipping after
> +appropriate transformation to the clipping cube.

The viewport doesn't describe a clipping rect.  It just happens that 
tris clipped to the NDC cube lie fully inside the viewport.  Wide 
lines and points will generate vertices and fragments outside the 
viewport.

Do we really want to require that the viewport do fragment clipping too?

I'd say it's up to the user to also set up a scissor rect if he really 
doesn't want to see any fragments outside the viewport.

-Brian