Emil, In situations such as your TEXTURE_TARGET example, the functionality is not exposed to non-DSA functions. I've been making the backend functions take a bool dsa that instructs them how to behave depending on whether or not glTexParameter or glTextureParameter is called. Now this is arguably more cumbersome than ctx->Extensions.ARB_direct_state_access, but it works to prevent the user from seeing DSA functionality that would confuse them.
Laura On Fri, Jan 23, 2015 at 2:20 PM, Emil Velikov <emil.l.veli...@gmail.com> wrote: > On 23/01/15 21:53, Jason Ekstrand wrote: > > > > > > On Fri, Jan 23, 2015 at 1:46 PM, Emil Velikov <emil.l.veli...@gmail.com > > <mailto:emil.l.veli...@gmail.com>> wrote: > > > > On 23/01/15 20:51, Jason Ekstrand wrote: > > > > > > > > > On Thu, Jan 22, 2015 at 9:27 AM, Emil Velikov < > emil.l.veli...@gmail.com <mailto:emil.l.veli...@gmail.com> > > > <mailto:emil.l.veli...@gmail.com > > <mailto:emil.l.veli...@gmail.com>>> wrote: > > > > > > On 05/01/15 17:45, Laura Ekstrand wrote: > > > > This comment is vague. Do you have a specific > > recommendation for the > > > > code here? > > > > > > > Seems like I'm way too subtle - yes I have a few. > > > > > > > > > 1. Add ARB_direct_state_access to struct gl_extension > > > --- a/src/mesa/main/mtypes.h > > > +++ b/src/mesa/main/mtypes.h > > > @@ -3731,6 +3731,7 @@ struct gl_extensions > > > GLboolean ARB_depth_clamp; > > > GLboolean ARB_depth_texture; > > > GLboolean ARB_derivative_control; > > > + GLboolean ARB_direct_state_access > > > GLboolean ARB_draw_buffers_blend; > > > GLboolean ARB_draw_elements_base_vertex; > > > > > > > > > 2. Use it in the extensions table. > > > --- a/src/mesa/main/extensions.c > > > +++ b/src/mesa/main/extensions.c > > > @@ -103,6 +103,7 @@ static const struct extension > > extension_table[] = { > > > { "GL_ARB_depth_clamp", > > o(ARB_depth_clamp), > > > GL, 2003 }, > > > { "GL_ARB_depth_texture", > > > o(ARB_depth_texture), GLL, > > 2001 }, > > > { "GL_ARB_derivative_control", > > > o(ARB_derivative_control), GL, > > 2014 }, > > > + { "GL_ARB_direct_state_access", > > > o(ARB_direct_state_access), GL, > > 2014 }, > > > > > > > > > 3. Make use of if when the spec amends existing behaviour - > > most of the > > > spec text as of section "New Tokens" onwards. Clearly with > > this series > > > you're adding the new entry points(functions) so it does not > apply > > > here :) > > > > > > > > > if (foo->Extensions.ARB_direct_state_access) { > > > .... > > > } > > > > > > > > > Pretty much every extension that was added to mesa follows > > this approach > > > so keeping up with traditions is always nice. > > > > > > > > > Yes, and no... We have the table of booleans in gl_extensions so > that > > > we can expose different extensions/behavior on different drivers. > > > However, ARB_direct_state_access doesn't actually add new > > functionality, > > > just new ways of getting at old functionality. We *should* be > able to > > > implement it in a driver-agnostic way entirely within core mesa. > > > Therefore, there's no reason to be able to shut it off on a > per-driver > > > basis and no reason for the flag in gl_extensions. If we find > > that, for > > > some reason, we only want to support it in core contexts or that > > it adds > > > something some drivers can't handle it, then we'll need the flag. > > True, yet the usual approach so far had been: > > 1. add the flag > > 2. enable when/where possible > > 3. evaluate if things can be enabled for everyone > > 4. drop it (replace with dummy_true). > > Why bother ? See below. > > > > > > The "usual approach" is for extensions that add functionality and > > require per-driver implementation. This extension is kind of unique in > > that *nothing* it adds is per-driver (as far as I know). > > > There has been other similar cases, yet I cannot pick one from the top > of my head. And yes I did understand that is has *nothing* driver > specific about it :) > > > > > There will be a point where the extension will still be dummy_false, > yet > > the amendments to the spec will be applied. > > > > > > What "ammendments to the spec"? Once it gets implemented, we'll turn it > on. > > > See note 3, that I've mentioned above. Here is a rough example: > > As you handle the following > " > Accepted by the <pname> parameter of GetTextureParameter{if}v and > GetTextureParameterI{i ui}v: > > TEXTURE_TARGET 0x1006 > " > > you will allow the pname, in a scenario when one should not. > I.e. the extension will not be advertised, yet the parameter will be > accepted and no error will be thrown. > > This is a silly example, yet I hope it illustrates the point. > > > > > At that point there will be a "few" reports from your QA team and > other > > people, that piglit (other) has regressed. Going the usual route will > > save you that, at the cost of having one extra commit worth > > (presumingly) ~50loc. > > > > Hope with ^^ things make (a bit more) sense :) > > > > > > Not really. Right now it's not even 100% implemented, so it needs to be > > off for everyone. > True, I'm not against that. > > > As far as anyone can tell, it will go directly from > > dummy_false to dummy_true. If we do find something in the way of > > implementing it that can't be done on some drivers, we can add the flag > > and then turn it on per-driver instead of turning it on for everyone. > > I'm really not seeing how a per-driver flag will do any good. > The idea behind the flag is to control/distinguish if the extension is > advertised _and_ if its functionality is enabled. > > Presently you're gradually enabling the functionality without > advertising the extension. As such there are going to be cases, where > you allow/forbid X or Y (as per the spec text), yet the user will be > confused, as mesa does not advertise support for arb_dsa. > > Does this shed more light on what I'm thinking ? > > -Emil >
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