[Mesa-dev] RFC: array textures in gallium and assorted cleanups

[Keith Whitwell]

On Thu, 2010-06-10 at 11:32 -0700, Roland Scheidegger wrote:
> On 10.06.2010 17:12, Keith Whitwell wrote:
> > On Thu, 2010-06-10 at 07:29 -0700, Brian Paul wrote:
> >> Keith Whitwell wrote:
> >>> On Thu, 2010-06-10 at 07:08 -0700, Roland Scheidegger wrote:
> >>>> On 10.06.2010 11:30, Keith Whitwell wrote:
> >>>>> On Thu, 2010-06-03 at 13:26 -0700, Roland Scheidegger wrote:
> >>>>>> Hi,
> >>>>>>
> >>>>>> I've created a new branch gallium-array-textures which has some more
> >>>>>> interface changes, this time to support array textures basically.
> >>>>>> Nothing has been adapted to these changes yet (I'll do that it should be
> >>>>>> mostly trivial as long as array textures aren't actually supported by
> >>>>>> the driver or even mesa state tracker), but now would be a good time if
> >>>>>> you have some comments for the proposed interface changes.
> >>>>>>
> >>>>>> Roland
> >>>>> Roland,
> >>>>>
> >>>>> This looks great!
> >>>>>
> >>>>> Couple of comments -- you're now using the term "layer" in various
> >>>>> places, but there is no strong definition of what that means - except in
> >>>>> the patch comment, which isn't useful once the patch is committed.  Can
> >>>>> you define this term somewhere in the documentation?
> >>>> Ok will do.
> >>>>
> >>>>> Also, there are a couple of things that look like typos in the interface
> >>>>> change diff, but I'm sure you'll find those the first time you try to
> >>>>> compile this.  eg:
> >>>>>
> >>>>>     void (*resource_copy_region)(struct pipe_context *pipe,
> >>>>>                                  struct pipe_resource *dst,
> >>>>> -                                struct pipe_subresource subdst,
> >>>>> +                                unsigned level,
> >>>>>                                  unsigned dstx, unsigned dsty, unsigned dstz,
> >>>>>                                  struct pipe_resource *src,
> >>>>> -                                struct pipe_subresource subsrc,
> >>>>> -                                unsigned srcx, unsigned srcy, unsigned srcz,
> >>>>> -                                unsigned width, unsigned height);
> >>>>> +                                unsigned level,
> >>>>> +                                const struct pipe_box *);
> >>>>>  
> >>>>> It seems like you end up with two parameters named "level" ??
> >>>> Yes, I had already fixed this locally.
> >>>> create_surface also had a bug (still got passed pipe_screen instead of
> >>>> pipe_context since it moved to context), as well as I need to store the
> >>>> context itself in pipe_surface (much like pipe_sampler_view does).
> >>>> That actually was a bit non-trivial since some state trackers don't
> >>>> really have a context handy when they called the former
> >>>> get_tex_surface() (glx, wgl and so on statetrackers not the rendering
> >>>> ones). Some of them did, though, already have their own context (for
> >>>> resource_copy_region, for instance) so I'm about to do this in a similar
> >>>> fashion.
> >>>> Actually, I was wondering if surface_destroy() should also get passed in
> >>>> a context - seems strange since it already stores the context, but this
> >>>> is exactly what sampler_view_destroy() does, which I'd like to see as a
> >>>> very analogous function.
> >>> Yes, it should take a context, mainly for consistency.  It helps when
> >>> wrapping/unwrapping these functions to have a consistent interface.  
> >> Yes.  The other reason is you have to be careful with objects that 
> >> save context pointers when those objects might be shared among 
> >> multiple contexts.
> >>
> >> If object A is created by context C1 and shared with context C2 and C1 
> >> gets destroyed, we're in trouble if we use A's stale context pointer. 
> >>   It's safer to use the context pointer that's passed to the function.
> >>
> >> I fixed a bug along those lines a couple months ago.  See 
> >> st_DeleteTextureObject().
> > 
> > Anything created by a context in gallium is private to that context.
> > The shareable entities are created in the screen.  In effect, Roland's
> > change makes surfaces private to the context.
> > 
> > That may have effects elsewhere, eg in the mesa state tracker, which may
> > be relying on sharing surfaces (aka render_target_views,
> > depth_stencil_views) between contexts.
> 
> I am actually wondering if we should have some different abstraction for
> "surfaces" which are used for presents etc. Clearly, the glx etc. state
> trackers have no intention for using these pipe_resources as render
> attachment points, hence it's not really the right abstraction.
> But I guess that can be figured out later.
> 
> There's something else which is a bit ugly currently. pipe_surface
> includes an offset. 

That's bogus & left over from some distant past.  Just remove it.

Keith