On 25.05.2015 17:07, Ilia Mirkin wrote:
On Mon, May 25, 2015 at 9:40 AM, Tobias Klausmann
<[email protected]> wrote:
On 25.05.2015 07:17, Dave Airlie wrote:
On 25 May 2015 at 08:11, Marek Olšák <[email protected]> wrote:
It's the same on Radeon. There are 2x ClipOrCullDistance output
vectors and a mask saying it should clip or cull or do nothing.
Marek
My thinking was gallium should have a single semantic and a mask in
the shader definition maybe.
though it doesn't solve the does nvidia do the right thing with
cull[0] and clip[0], and what is the right thing.
Dave.
I'm still convinced that both clip[0] and cull[0] should be possible. Plus i
have written a shader_test for this a while ago which you pushed to piglit
(fs-cull-and-clip-distance-different.shader_test). If i remember right
nvidia passed that test just fine.
My take (and note that I last read the extension many months ago) is
that you're supposed to figure out the max gl_ClipDistance[] written,
and then write all your cull distances above that. So if you, e.g.,
have something like
gl_ClipDistance[5] = 1;
gl_CullDistance[0] = 1;
Then it would decide that there are 6 clip distances (or if there's an
explicit out float gl_ClipDistance[n], then use that), and 1 cull
distance. In the TGSI, I'm thinking this might look approximately like
PROPERTY CULL_MASK (1<<6)
DCL OUT[0], CLIPDIST[0]
DCL OUT[1], CLIPDIST[1]
MOV OUT[1].y, 1 (clip distance[5])
MOV OUT[1].z, 1 (cull distance[0])
Then basically you'd have
(rast->clip_enable & shader->actual_clip_writes_mask) | cull_mask =
the enabled distances
cull_mask = cull mask
This would work *very* well for nouveau, not sure how suitable it is
for other hardware.
Cheers,
-ilia
I wonder where this step should be implemented after all. It was brought
up that llvmpipe already supports cull_distance (it does!), so maybe we
should implement this in the drivers to evade llvmpipe breakage. Any
suggestions appreciated :)
Tobias
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