Hey, thanks for your quick answer!
I actually had the version you described first running. I obtained the rendered image using QRenderCapture and then displayed it on the quad. I also already had the second idea that you described but thought it should be possible to obtain the texture from Qt3D and use it in OpenGL that's why I hadn't investigated this any further. Unfortunately, it's pretty difficult to run the aspect engine manually. I tried to place a processFrame() call in paintGL() - and even placed a doRender() call to the AbstractRenderer of the QRenderAspectPrivate after it like this: d->m_aspectEngine->processFrame(); glClearColor(1.0, 1.0, 1.0, 1.0); glDisable(GL_BLEND); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); Qt3DRender::QRenderAspectPrivate *dRenderAspect = static_cast<decltype(dRenderAspect)> (Qt3DRender::QRenderAspectPrivate::get(d->m_renderAspect)); Qt3DRender::Render::AbstractRenderer *renderer = dRenderAspect->m_renderer; renderer->doRender(true); Without the doRender() call it gets stuck the second time processFrame() is called - in Qt3DRender::Render::VSyncFrameAdvanceService::waitForNextFrame() where it tries to acquire a semaphore (which apparently doesn't have any more work ready). With the doRender() call it gets stuck in a similar place - but in the first call to paintGL in Qt3DRender::Render::Renderer::isReadyToSubmit() where it again tries to acquire a semaphore. I also don't understand whether it's enough that QOpenGLWidget binds a framebuffer before calling paintGL, it looks like in Scene3DRenderer this is enough to make Qt3D draw to that framebuffer. As you can see there are a lot of open questions which are difficult to answer. Do you have any suggestions where/how to look for answers? Obviously in the code itself, which is also difficult. Any help is appreciated, Florian On 01.09.20 18:28, Mike Krus wrote: > Hi > > Qt 3D source code has an example of how to use render capture in the manual > tests. > > However this is probably not the right way to do it as 1/ it would require > another FBO on top of the one QOpenGLWidget uses already; 2/ it transfers the > image to the CPU which is not needed here. > > Think the way to do it is to do something similar to what is done for Scene3D: > - setup Qt 3D engine to be in manual mode (rather than using the simulation > loop) > by calling QAspectEngine::setRunMode(QAspectEngine::Manual) > - use QOpenGLWidget and in the paintGL method call > QAspectEngine::processFrame() > to have Qt 3D draw > > There’s of course lots of other stuff to setup. Might need a dummy offscreen > surface to handle sizing, handling of the context, and a fair amount more. > > Mike > >> On 1 Sep 2020, at 16:51, Florian Blume <florian.bl...@tu-berlin.de> wrote: >> >> Hi, >> >> I'm trying to implement a Qt3D widget since createWindowContainer is not >> suitable for me (always draws the Qt3DWindow on top of everything). >> I've already asked a Stackverflow question >> (https://stackoverflow.com/questions/63686309/use-qt3d-offscreen-rendered-texture-in-opengl) >> because I ran into >> several issues trying to display an offscreen texture that I render to >> with Qt3D in a QOpenGLWidget (it simply doesn't display anything). >> >> Has anyone some other solution regarding a Qt3D widget? >> >> Best regards, >> Florian >> _______________________________________________ >> Interest mailing list >> Interest@qt-project.org >> https://lists.qt-project.org/listinfo/interest > — > Mike Krus | mike.k...@kdab.com | Senior Software Engineer > KDAB (UK) Ltd., a KDAB Group company > Tel: UK Office +44 1625 809908 Mobile +44 7833 491941 > KDAB - The Qt Experts, C++, OpenGL Experts > > _______________________________________________ Interest mailing list Interest@qt-project.org https://lists.qt-project.org/listinfo/interest
