[Interest] Qt3D - Render to QImage
Juan Jose Casafranca
jjcasmar at gmail.com
Tue Dec 20 01:18:15 CET 2016
Hi,
I've began to look a the QRenderCapture code to implement the
QBufferCapture node and I've found that the problem that Philip described
may happen because of the render target format used.
The debugger says that the render target is a RGB8_UNorm which is not
considered in the big switch case statement in
graphicshelpers/graphicscontext.cpp file (line 1624).
I will file a jira with this info
2016-12-12 15:43 GMT+01:00 Philip Schuchardt <vpicaver at gmail.com>:
> I'm using Scene3D in my QML application. Qt Quick is in charge. The
> default format returns -1, -1, -1, and -1 for alpha, red, green, and blue.
> I'm on macOS 10.12.1 with an AMD Radeon HD 6770M 1024 MB.
>
> On Fri, Dec 9, 2016 at 3:26 AM Sean Harmer <sean.harmer at kdab.com> wrote:
>
>>
>>
>> On 09/12/2016 00:28, Philip Schuchardt wrote:
>> > I figured out why it wasn't working for me. After using the qt3d debug
>> > build, I noticed that Qt3D was asserting:
>> >
>> > ASSERT failure in Q_UNREACHABLE(): "Q_UNREACHABLE was reached", file
>> > graphicshelpers/graphicscontext.cpp, line 1684
>> >
>> >
>> > Basically, it was telling me that it had an invalid framebuffer type. I
>> > had multisampling enabled which would prevent direct reads from a
>> > framebuffer. Multisampled framebuffers need to be copied to a texture
>> > before reading to main memory. After disabling multisampling, it still
>> > wasn't working. Then I forced a new default format with QSurfaceFormat:
>>
>> Right. We could handle this multisample resolving internally so please
>> do file a bug report for this. I also want to add a framebuffer blit
>> framegraph node for 5.9 too as this has other uses outside of
>> RenderCapture.
>>
>> >
>> >
>> > QSurfaceFormatformat=QSurfaceFormat::defaultFormat();
>> >
>> > format.setAlphaBufferSize(8);
>> >
>> > format.setRedBufferSize(8);
>> >
>> > format.setGreenBufferSize(8);
>> >
>> > format.setBlueBufferSize(8);
>> >
>> > QSurfaceFormat::setDefaultFormat(format);
>> >
>> >
>> > Then it worked! I tried re-enabling multisampling which caused it not to
>> > work agian.
>> >
>> >
>> > I think there's currently two bugs for RenderCapture:
>> >
>> > 1. The default QSurfaceFormat doesn't work with RenderCapture (on macOS
>> > 10.12.1)
>>
>> What setup are you using? Qt QUick in charge + a Scene3D or pure QT 3D
>> application? What is the default format you get in this case?
>>
>> >
>> > 2. The multisampling (using Scene3D) doesn't work with RenderCapture
>> >
>> >
>> > Sean, should I make a bug report?
>>
>> Yes please :)
>>
>> Thanks for investigating!
>>
>> Sean
>>
>> >
>> >
>> > Thanks,
>> >
>> > Phi|ip
>> >
>> >
>> > On Sat, Dec 3, 2016 at 4:16 PM Philip Schuchardt <vpicaver at gmail.com
>> > <mailto:vpicaver at gmail.com>> wrote:
>> >
>> > I prototyped a framegraph using 5.8-beta and RenderCapture, but was
>> > unable to get anything to save to disk. It creates a
>> > RenderCaptureReply. The reply gets completed but the image is null
>> > and nothing is saved. I'm currently saving to "~/testShot.png". Any
>> > ideas why it's not working? I probably set up the framegraph wrong
>> > or something. I would be really helpful if there was an example in
>> > the documentation.
>> >
>> > Here's my test example. You can run through Qt Creators -> Tools ->
>> > External -> Qt Quickt - > qmlscene
>> > https://dl.dropboxusercontent.com/u/13470469/Renderer3D.qml
>> >
>> > On Mon, Nov 28, 2016 at 11:33 AM Philip Schuchardt
>> > <vpicaver at gmail.com <mailto:vpicaver at gmail.com>> wrote:
>> >
>> > Cool! I didn't see RenderCapture class in 5.7. I glad it was
>> > added in 5.8. I'll try to prototype something with custom
>> > framegraph in 5.8.
>> >
>> > Phi|ip
>> >
>> > On Mon, Nov 28, 2016 at 6:48 AM Juan Jose Casafranca
>> > <jjcasmar at gmail.com <mailto:jjcasmar at gmail.com>> wrote:
>> >
>> > I will have a better look to how the aspect translates the
>> > framegraph node to opengl commands.
>> >
>> > Thanks!
>> >
>> > 2016-11-28 12:42 GMT+01:00 Sean Harmer <
>> sean.harmer at kdab.com
>> > <mailto:sean.harmer at kdab.com>>:
>> >
>> > On Monday 28 November 2016 12:34:01 Juan Jose Casafranca
>> > wrote:
>> > > How does QRenderCapture works? When a capture is
>> requested it sets a flags
>> > > and when generating the view, it creates a job that
>> will render the image?
>> > > I imagine the QRenderCapture in the framegraph is
>> important. If you put it
>> > > right after the ClearBuffers, it will render an empty
>> image, wont it?
>> >
>> > I suspect the issue here is not being clear on the frame
>> > graph. Each leaf node
>> > of the frame graph results in a phase of rendering. The
>> > RenderCapture node
>> > essentially gets translated into a glReadPixels call for
>> > that rendering phase.
>> > If the sub-tree containing the ClearBuffers and
>> > RenderCapture also does some
>> > drawing (i.e. doesn't have a NoDraw node) the
>> > glReadPixels will happen after
>> > the draw calls so should read back the framebuffer that
>> > has just been drawn
>> > to.
>> >
>> > Hope this helps,
>> >
>> > Sean
>> >
>> > >
>> > > 2016-11-28 12:11 GMT+01:00 Sean Harmer
>> > <sean.harmer at kdab.com <mailto:sean.harmer at kdab.com>>:
>> > > > On Monday 28 November 2016 11:48:14 Harald Vistnes
>> > wrote:
>> > > > > 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 meant for reading back from a buffer. :)
>> > > >
>> > > > > 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.
>> > > >
>> > > > I'll see if someone can take a look. I may have some
>> > time next week if
>> > > > nobody
>> > > > else can.
>> > > >
>> > > > Cheers,
>> > > >
>> > > > Sean
>> > > >
>> > > > > Thanks,
>> > > > > Harald
>> > > > >
>> > > > > 2016-11-28 11:41 GMT+01:00 Sean Harmer
>> > <sean.harmer at kdab.com <mailto: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 <mailto: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 <mailto: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
>> > <mailto:sean.harmer at kdab.com> | Managing Director UK
>> > > > > > > > > > KDAB (UK) Ltd, a KDAB Group company
>> > > > > > > > > > Tel. +44 (0)1625 809908
>> <+44%201625%20809908>
>> > <tel:%2B44%20%280%291625%20809908>; Sweden (HQ)
>> > +46-563-540090 <+46%20563%2054%2000%2090>
>> <tel:%2B46-563-540090>
>> > > > > > > > > > Mobile: +44 (0)7545 140604
>> <+44%207545%20140604>
>> > <tel:%2B44%20%280%297545%20140604>
>> > > > > > > > > > KDAB - Qt Experts
>> > > > > > > > > >
>> > _______________________________________________
>> > > > > > > > > > Interest mailing list
>> > > > > > > > > > Interest at qt-project.org
>> > <mailto:Interest at qt-project.org>
>> > > > > > > > > >
>> > http://lists.qt-project.org/mailman/listinfo/interest
>> > > > > > > >
>> > > > > > > > --
>> > > > > > > > Dr Sean Harmer | sean.harmer at kdab.com
>> > <mailto:sean.harmer at kdab.com> | Managing Director UK
>> > > > > > > > KDAB (UK) Ltd, a KDAB Group company
>> > > > > > > > Tel. +44 (0)1625 809908
>> <+44%201625%20809908>
>> > <tel:%2B44%20%280%291625%20809908>; Sweden (HQ)
>> > +46-563-540090 <+46%20563%2054%2000%2090>
>> <tel:%2B46-563-540090>
>> > > > > > > > Mobile: +44 (0)7545 140604
>> <+44%207545%20140604>
>> > <tel:%2B44%20%280%297545%20140604>
>> > > > > > > > KDAB - Qt Experts
>> > > > > >
>> > > > > > --
>> > > > > > Dr Sean Harmer | sean.harmer at kdab.com
>> > <mailto:sean.harmer at kdab.com> | Managing Director UK
>> > > > > > KDAB (UK) Ltd, a KDAB Group company
>> > > > > > Tel. +44 (0)1625 809908 <+44%201625%20809908>
>> > <tel:%2B44%20%280%291625%20809908>; Sweden (HQ)
>> > +46-563-540090 <+46%20563%2054%2000%2090>
>> <tel:%2B46-563-540090>
>> > > > > > Mobile: +44 (0)7545 140604
>> <+44%207545%20140604>
>> > <tel:%2B44%20%280%297545%20140604>
>> > > > > > KDAB - Qt Experts
>> > > > > > _______________________________________________
>> > > > > > Interest mailing list
>> > > > > > Interest at qt-project.org
>> > <mailto:Interest at qt-project.org>
>> > > > > >
>> > http://lists.qt-project.org/mailman/listinfo/interest
>> > > >
>> > > > --
>> > > > Dr Sean Harmer | sean.harmer at kdab.com
>> > <mailto:sean.harmer at kdab.com> | Managing Director UK
>> > > > KDAB (UK) Ltd, a KDAB Group company
>> > > > Tel. +44 (0)1625 809908 <+44%201625%20809908>
>> > <tel:%2B44%20%280%291625%20809908>; Sweden (HQ)
>> > +46-563-540090 <+46%20563%2054%2000%2090>
>> <tel:%2B46-563-540090>
>> > > > Mobile: +44 (0)7545 140604 <+44%207545%20140604>
>> > <tel:%2B44%20%280%297545%20140604>
>> > > > KDAB - Qt Experts
>> > > > _______________________________________________
>> > > > Interest mailing list
>> > > > Interest at qt-project.org <mailto:
>> Interest at qt-project.org>
>> > > > http://lists.qt-project.org/
>> mailman/listinfo/interest
>> >
>> > --
>> > Dr Sean Harmer | sean.harmer at kdab.com
>> > <mailto:sean.harmer at kdab.com> | Managing Director UK
>> > KDAB (UK) Ltd, a KDAB Group company
>> > Tel. +44 (0)1625 809908 <+44%201625%20809908>
>> <tel:+44%201625%20809908>;
>> > Sweden (HQ) +46-563-540090 <+46%20563%2054%2000%2090>
>> <tel:+46%20563%2054%2000%2090>
>> > Mobile: +44 (0)7545 140604 <+44%207545%20140604>
>> <tel:+44%207545%20140604>
>> > KDAB - Qt Experts
>> >
>> >
>> > _______________________________________________
>> > Interest mailing list
>> > Interest at qt-project.org <mailto:Interest at qt-project.org>
>> > http://lists.qt-project.org/mailman/listinfo/interest
>> >
>> > --
>> > Phi|ip
>> >
>> > --
>> > Phi|ip
>> >
>> > --
>> > Phi|ip
>> >
>> >
>> > _______________________________________________
>> > 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 <+44%201625%20809908>; Sweden (HQ) +46-563-540090
>> <+46%20563%2054%2000%2090>
>> Mobile: +44 (0)7545 140604 <+44%207545%20140604>
>> KDAB - Qt Experts
>> _______________________________________________
>> Interest mailing list
>> Interest at qt-project.org
>> http://lists.qt-project.org/mailman/listinfo/interest
>>
> --
> Phi|ip
>
> _______________________________________________
> Interest mailing list
> Interest at qt-project.org
> http://lists.qt-project.org/mailman/listinfo/interest
>
>
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