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

[Roland Scheidegger]

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...

Roland