[Interest] Qt3D - Render to QImage

[Sean Harmer]

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
> > > > _______________________________________________
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> > > > 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