On 21 January 2011 22:49, Robert Bragg <[email protected]> wrote:
> Excerpts from James Moschou's message of Thu Jan 20 13:47:17 +0000 2011:
>> On 20 January 2011 03:38, Robert Bragg <[email protected]> wrote:
>> > Excerpts from James Moschou's message of Wed Jan 19 04:56:48 +0000 2011:
>> >> > There is a visual debugging aid available if you export
>> >> > CLUTTER_PAINT=redraws or CLUTTER_PAINT=paint-volumes before running you
>> >> > application which can show what parts of the stage are being redrawn.
>> >>
>> >> I'm having trouble with this. How exactly do they show what parts of
>> >> the stage are being drawn? Do they flash a rectangle over the stage,
>> >> or is it more like console output? I don't know what I'm supposed to
>> >> be looking for.
>> > For CLUTTER_PAINT=redraws you should see a clear red outline
>> > highlighting the sub-region that was last redrawn. For
>> > CLUTTER_PAINT=paint-volumes you should see a 3D wire, bounding box around
>> > all actors. If the actor isn't actually able to report a paint-volume
>> > then the box will be blue and will correspond to the actor's allocation
>> > box. If it does report a paint-volume then the wireframe will be green.
>> > All the boxes will also be labeled with the actor's type - though
>> > sometimes this can look very cluttered.
>> >
>> > Probably if you aren't seeing anything then you will need to re-build
>> > your clutter with --enable-debug=yes and --enable-cogl-debug=yes
>> >
>> > A common gotcha with the optimization to automatically queue
>> > clipped-redraws is that application code that g_signal_connects to the
>> > "paint" signal of an actor will effectively disable that actor from
>> > being able to report a paint-volume so it can't queue clipped redraws.
>> > The reason is that clutter has no idea what the application might be
>> > doing in that paint_handler so it has to assume that it is painting
>> > outside the reported paint-volume and so by disabling the paint-volume
>> > the actor's volume effectively becomes the size of the stage.
>> >
>> > At the moment there isn't a convenient way to determine if your
>> > application is doing that besides from manually checking your code or if
>> > you build clutter from source then look at the implementation of
>> > _clutter_actor_get_paint_volume_mutable and you will see that we
>> > test for this using g_signal_has_handler_pending and you can set a break
>> > point on the failure case and hopefully the backtrace will help you find
>> > the offending paint handler.
>> >
>> > Just to clarify a bit; the odd paint handler used for a few actors in
>> > your scene shouldn't completely disable the benefits of clipped-redraws
>> > it's just the actors queuing redraws for a sub-region of the stage that
>> > shouldn't have paint handlers. I.e. having some kind of icon actor in
>> > the corner if your window with a "paint" handler shouldn't stop
>> > automatic clipped redraws working for mousing over buttons in the middle
>> > if the screen.
>> >
>> > It might be worth verifying that you can get the debug options working
>> > with some of clutter's tests/interactive tests (e.g. I tested a lot with
>> > test-state for the when adding the automatic clipped-redraws support)
>> >
>> >>
>> >> I haven't really noticed a difference in performance. All I have done
>> >> is duplicate the implementation of get_paint_volume I found in
>> >> Clutter.Rectangle. Is this the idea, or does it need to be smarter in
>> >> some way? Do I need to mark actors as needing to be updated, or does
>> >> that happen automatically?
>> > In a lot of cases a get_paint_volume implementation like this should do:
>> >  static gboolean
>> >  my_actor_get_paint_volume (ClutterActor       *self,
>> >                            ClutterPaintVolume *volume)
>> >  {
>> >   return clutter_paint_volume_set_from_allocation (volume, self);
>> >  }
>> >
>> > What we do, in addition, for most actors provided by Clutter though is
>> > also explicitly check the GType of the actor so we don't make
>> > assumptions about the paint-volume of sub-classes. You might want to
>> > also do that if you are providing a toolkit and you don't know how some
>> > of your actors may have been sub-classed. For new actors though it may
>> > be best to avoid this though and simply require that sub-classes that
>> > escape the default paint-volume should also provide a new
>> > get_paint_volume implementation.
>> >
>> > The GType can be checked in your get_paint_volume implementation for
>> > example like:
>> >  if (G_OBJECT_TYPE (self) != CLUTTER_TYPE_TEXTURE)
>> >    return FALSE;
>> >
>> > I hope that helps,
>> > regards,
>> > - Robert
>> >>
>> >> Regards,
>> >> James
>> > --
>> > Robert Bragg, Intel Open Source Technology Center
>> >
>>
>> Thanks Robert,
>>
>> I hadn't compiled clutter with the debug options. The other half to my
>> problem was that I wasn't setting LD_LIBRARY_PATH.
>>
>> CLUTTER_PAINT=paint-volumes is working as expected: A whole mess of
>> green rectangles, although the stage one is blue.
>>
>> CLUTTER_PAINT=redraws is not working, I still see nothing. I am
>> definitely not connecting to any paint signals. I checked with gdb and
>> some printfs, and every actor is reporting its paint volume correctly.
>> Do you have any tips on how to find the cause of the problem? The
>> stage is inside a GtkClutter.Embed and libclutter-gtk is still version
>> 0.10.4 if that is significant.
>
> I assume you are using glx not egl? For glx; clipped redraws depend on
> you either having the GLX_MESA_copy_sub_buffer extension or
> GL_EXT_framebuffer_blit extension which you can check for via glxinfo.
>
> Also note that there is a short warm up period of ~5 frames when your
> app starts where clipped redraws aren't used.
>
> I guess your problem might be something more involved, but perhaps good
> to check these first.
>
> regards,
> - Robert
>
>>
>> Regards,
>> James
> --
> Robert Bragg, Intel Open Source Technology Center
>

I think I've identified the problem as
Clutter.PaintVolume.set_from_allocation is failing for all actors
whose "visible" property is set to false. But I'm not sure where to go
from here.

Cheers,
James
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