[Interest] Qt3D - Render to QImage

[Harald Vistnes]

Hi,

yes, this would be a most welcome feature.

Concerning Jira, it has already been requested multiple times
https://bugreports.qt.io/browse/QTBUG-52074
https://bugreports.qt.io/browse/QTBUG-52136

I tried to render into a FBO and read back the results, but had some
problems. I attached some test code in the Jira
https://bugreports.qt.io/secure/attachment/57353/offscreenrenderer.zip but
never got any feedback. If someone will look into this it would be great.

Thanks,
Harald




2016-11-28 11:41 GMT+01:00 Sean Harmer <sean.harmer at kdab.com>:

> On Monday 28 November 2016 11:40:10 Juan Jose Casafranca wrote:
> > Oh thanks!
> >
> > Yes, in fact my first thought was to use it for a compute shader. It
> would
> > make Qt3D a great tool not only for rendering but also for GPGPU.
> > I will try to have a look on it during the Christmas vacations :-)
>
> Awesome! Drop by #qt-3d on irc if you need anything.
>
> Cheers,
>
> Sean
>
> >
> > 2016-11-28 11:31 GMT+01:00 Sean Harmer <sean.harmer at kdab.com>:
> > > Hi,
> > >
> > > On Monday 28 November 2016 11:22:30 Juan Jose Casafranca wrote:
> > > > Hi Sean,
> > > >
> > > > is there any example on how to do that? I tried to use a
> QRenderCapture
> > >
> > > but
> > >
> > > > I failed two weeks ago.
> > >
> > > http://code.qt.io/cgit/qt/qt3d.git/tree/tests/manual/rendercapture-qml
> > > http://code.qt.io/cgit/qt/qt3d.git/tree/tests/manual/rendercapture-cpp
> > >
> > > > Is there any way to access the buffers content data using a similar
> > > > approach to the QRenderCapture method?
> > > > For example, in an animation system, use a graphics pipeline to
> compute
> > >
> > > the
> > >
> > > > deformed mesh and then get the new vertex positions for export.
> > >
> > > Right, that is missing at the moment. It would be very useful to be
> able
> > > to do
> > > this to read back the results of a compute shader too for e.g.. If you
> > > wish to
> > > have a go at adding such a feature analogous the the RenderCapture node
> > > then
> > > that would be awesome. If not, we can try to do it for 5.9 but the
> feature
> > > freeze is approaching. In either case could you file a JIRA for it
> please?
> > >
> > > Thanks!
> > >
> > > Sean
> > >
> > > > Cheers
> > > > Juan José
> > > >
> > > > 2016-11-28 11:13 GMT+01:00 Sean Harmer <sean.harmer at kdab.com>:
> > > > > On Monday 28 November 2016 02:23:59 Philip Schuchardt wrote:
> > > > > > I'm trying to port my OpenGL code (https://github.com/Cavewhere/
> > > > >
> > > > > cavewhere/)
> > > > >
> > > > > > to use Qt3D. I think Qt3D will allow me to quickly improve and
> > >
> > > modify my
> > >
> > > > > > rendering pipeline. The one requirement I need is to be able to
> > >
> > > render
> > >
> > > > > to a
> > > > >
> > > > > > QImage and save it to disk. Currently, have a method that renders
> > > > > > high-resolution images from OpenGL. I do this by tiling a
> projection
> > > > >
> > > > > matrix
> > > > >
> > > > > > and rendering the scene one tile at a time and combining them
> into
> > > > > > on
> > > > >
> > > > > huge
> > > > >
> > > > > > PNG. The problem is I'm not sure how to render Qt3D pipeline to a
> > > > > > texture
> > > > > > and then download if from the GPU into memory in Qt3D. Is there
> an
> > >
> > > easy
> > >
> > > > > way
> > > > >
> > > > > > to do that? Do I need to create my own Aspect?
> > > > >
> > > > > Hi, you can use a custom frame graph that includes a QRenderCapture
> > >
> > > node
> > >
> > > > > (coming in Qt 5.8). If you combine this with a camera and some
> logic
> > >
> > > for
> > >
> > > > > tiling the frustum (NodeInstantiator) you should be able to
> replicate
> > >
> > > your
> > >
> > > > > existing logic. I'd like to get something like this wrapped up
> along
> > >
> > > with
> > >
> > > > > Qt
> > > > > 5.9.
> > > > >
> > > > > > Also, many parts of the documentation seem to be missing, very
> > > > > > light,
> > > > > > and
> > > > > > not up to the same standard as the rest of Qt's documentation.
> > > > >
> > > > > Yes this is something I really want to have a push on in the near
> > >
> > > future.
> > >
> > > > > Cheers,
> > > > >
> > > > > Sean
> > > > >
> > > > > > Perhaps,
> > > > > > I'm just missing something from the undocumented documentation.
> > > > > >
> > > > > > Thanks,
> > > > > > Phi|ip
> > > > >
> > > > > --
> > > > > Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
> > > > > KDAB (UK) Ltd, a KDAB Group company
> > > > > Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
> > > > > Mobile: +44 (0)7545 140604
> > > > > KDAB - Qt Experts
> > > > > _______________________________________________
> > > > > Interest mailing list
> > > > > Interest at qt-project.org
> > > > > http://lists.qt-project.org/mailman/listinfo/interest
> > >
> > > --
> > > Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
> > > KDAB (UK) Ltd, a KDAB Group company
> > > Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
> > > Mobile: +44 (0)7545 140604
> > > KDAB - Qt Experts
>
> --
> Dr Sean Harmer | sean.harmer at kdab.com | Managing Director UK
> KDAB (UK) Ltd, a KDAB Group company
> Tel. +44 (0)1625 809908; Sweden (HQ) +46-563-540090
> Mobile: +44 (0)7545 140604
> KDAB - Qt Experts
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest
>
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