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

[Keith Whitwell]

On Thu, 2010-06-10 at 12:23 -0700, Roland Scheidegger wrote:
> On 10.06.2010 21:14, Keith Whitwell wrote:
> > 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.
> 
> It is used in a lot of places still. Granted if drivers want to
> precalculate that they should do that in a driver specific subclass of
> pipe_surface, but the change in fact is already huge as-is...

OK - if you want to defer removing it, that's ok - it's not really
related to array textures.  Maybe just add a deprecated comment and get
back to it later.

Keith