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A weird bug? Why is there no spatial depth in my 3D scene?

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qt3dqt 5.7
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  • F Finn

    @kshegunov My OS is ubuntu 16.04 LTS and I got Qt 5.7 via the qt-unified-x64-2.03-1-online.run executable. In the terminal, I went into my Qt directory
    /home/<username>/Qt/5.7/Src where I just entered

    ./configure
    make
    sudo make install
    

    When wanted to compile a Qt3D example, I got some linking errors saying something about missing Qt3D libraries (which I cannot recall anymore). I could solve this by entering the following which I found in some forum:

    sudo apt-get install libfontconfig1-dev libfreetype6-dev libx11-dev libxext-dev libxfixes-dev libxi-dev libxrender-dev libxcb1-dev libx11-xcb-dev libxcb-glx0-dev libxcb-keysyms1-dev libxcb-image0-dev libxcb-shm0-dev libxcb-icccm4-dev libxcb-sync0-dev libxcb-xfixes0-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-render-util0-dev libxcb-xinerama0-de
    

    Maybe this is the origin of my problems?
    Should I consider reinstalling Qt completely and what would be the cleanest way to do it? Thanks a lot for your help.

    kshegunovK Offline
    kshegunovK Offline
    kshegunov
    Moderators
    wrote on last edited by
    #13

    @Finn said in A weird bug? Why is there no spatial depth in my 3D scene?:

    Maybe this is the origin of my problems?

    It's certainly possble.

    sudo make install
    

    Why do that? Your distro already provides a Qt release so my suspicion is there are some files (partially) overwritten. What I suggest is to reinstall you distro's Qt (by means of the package manager), then to configure the Qt you downloaded with a prefix (don't forget to make clean before doing the configure, or even to delete the whole folder and recreate it through the Qt installer), e.g.:

    ./configure -prefix /opt/Qt-5.7
    

    make and then it's safe to make install, because the files will go to /opt/Qt-5.7.
    Then you can configure a kit in creator (assuming this is what you use) that will use this version of Qt (in /opt/Qt-5.7).

    Read and abide by the Qt Code of Conduct

    F 1 Reply Last reply
    1
    • kshegunovK kshegunov

      @Finn said in A weird bug? Why is there no spatial depth in my 3D scene?:

      Maybe this is the origin of my problems?

      It's certainly possble.

      sudo make install
      

      Why do that? Your distro already provides a Qt release so my suspicion is there are some files (partially) overwritten. What I suggest is to reinstall you distro's Qt (by means of the package manager), then to configure the Qt you downloaded with a prefix (don't forget to make clean before doing the configure, or even to delete the whole folder and recreate it through the Qt installer), e.g.:

      ./configure -prefix /opt/Qt-5.7
      

      make and then it's safe to make install, because the files will go to /opt/Qt-5.7.
      Then you can configure a kit in creator (assuming this is what you use) that will use this version of Qt (in /opt/Qt-5.7).

      F Offline
      F Offline
      Finn
      wrote on last edited by
      #14

      @kshegunov No, I completely reinstalled everything to the folder /opt/Qt-5.7 by following your instructions and those in the tutorial (https://wiki.qt.io/Install_Qt_5_on_Ubuntu). Before, I deleted everything but the result is the same. So far I used CLion2016 and now I also tried the QtCreator - still the same outcome.

      I also added some axes (x=red, y=green, z=blue), which are instantiated after the spheres.

      view 1
      view 2

      Other ideas?

      main.cpp

      #include <QGuiApplication>
      #include <Qt3DCore>
      #include <Qt3DRender>
      #include <Qt3DExtras>
      
      Qt3DCore::QEntity* createTestScene() {
      
        Qt3DCore::QEntity* root = new Qt3DCore::QEntity;
        Qt3DCore::QEntity* smallGreenSphere = new Qt3DCore::QEntity(root);
        Qt3DCore::QEntity* bigRedSphere = new Qt3DCore::QEntity(root);
      
      
        Qt3DExtras::QSphereMesh* bigMesh = new Qt3DExtras::QSphereMesh;
        bigMesh->setRadius(5);
        bigMesh->setRings(100);
        bigMesh->setSlices(20);
      
        Qt3DExtras::QSphereMesh* smallMesh = new Qt3DExtras::QSphereMesh;
        smallMesh->setRadius(2);
        smallMesh->setRings(100);
        smallMesh->setSlices(20);
      
        Qt3DExtras::QPhongMaterial* redMaterial = new Qt3DExtras::QPhongMaterial;
        redMaterial->setSpecular(Qt::white);
        redMaterial->setShininess(10);
        redMaterial->setAmbient(Qt::red);
      
        Qt3DExtras::QPhongMaterial* greenMaterial = new Qt3DExtras::QPhongMaterial;
        greenMaterial->setSpecular(Qt::white);
        greenMaterial->setShininess(10);
        greenMaterial->setAmbient(Qt::green);
      
      
        Qt3DCore::QTransform* transform =  new Qt3DCore::QTransform;
        transform->setTranslation(QVector3D(0,0,10));
      
        bigRedSphere->addComponent(redMaterial);
        bigRedSphere->addComponent(bigMesh);
      
        smallGreenSphere->addComponent(greenMaterial);
        smallGreenSphere->addComponent(smallMesh);
        smallGreenSphere->addComponent(transform);
      
        Qt3DCore::QEntity* xaxis = new Qt3DCore::QEntity(root);
        Qt3DCore::QEntity* yaxis = new Qt3DCore::QEntity(root);
        Qt3DCore::QEntity* zaxis = new Qt3DCore::QEntity(root);
      
        Qt3DExtras::QCylinderMesh* cylinderMesh = new Qt3DExtras::QCylinderMesh;
        cylinderMesh->setRadius(0.2);
        cylinderMesh->setLength(20);
        cylinderMesh->setRings(100);
        cylinderMesh->setSlices(20);
      
        Qt3DExtras::QPhongMaterial* blueMaterial = new Qt3DExtras::QPhongMaterial;
        blueMaterial->setSpecular(Qt::white);
        blueMaterial->setShininess(10);
        blueMaterial->setAmbient(Qt::blue);
      
        double pi = 3.14159265359;
        Qt3DCore::QTransform* xTransform = new Qt3DCore::QTransform();
        xTransform->setTranslation(QVector3D(10,0,0));
        xTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(0,0,1),90));
        Qt3DCore::QTransform* yTransform = new Qt3DCore::QTransform();
        yTransform->setTranslation(QVector3D(0,10,0));
        Qt3DCore::QTransform* zTransform = new Qt3DCore::QTransform();
        zTransform->setTranslation(QVector3D(0,0,10));
        zTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1,0,0),90));
      
      
        xaxis->addComponent(cylinderMesh);
        xaxis->addComponent(redMaterial);
        xaxis->addComponent(xTransform);
        yaxis->addComponent(cylinderMesh);
        yaxis->addComponent(greenMaterial);
        yaxis->addComponent(yTransform);
        zaxis->addComponent(cylinderMesh);
        zaxis->addComponent(blueMaterial);
        zaxis->addComponent(zTransform);
      
        return root;
      }
      
      
      int main(int argc, char* argv[]) {
      
        QGuiApplication app(argc, argv);
        Qt3DExtras::Qt3DWindow view;
        Qt3DCore::QEntity* scene = createTestScene();
      
        // camera
        Qt3DRender::QCamera *camera = view.camera();
        camera->lens()->setPerspectiveProjection(45, 16./9., 0.1,1000.);
        camera->setPosition(QVector3D(45,15,45));
        camera->setViewCenter(QVector3D(0, 0, 0));
      
        // manipulator
        Qt3DExtras::QOrbitCameraController* manipulator = new Qt3DExtras::QOrbitCameraController(scene);
        manipulator->setLinearSpeed(50);
        manipulator->setLookSpeed(180);
        manipulator->setCamera(camera);
      
        view.setRootEntity(scene);
      
        view.show();
      
        return app.exec();
      }
      
      

      CMakeLists.txt

      cmake_minimum_required(VERSION 3.2)
      
      project(QtCreatorTest)
      
      find_package(Qt5 REQUIRED COMPONENTS
              Core
              Gui
              Widgets
              3DCore
              3DExtras
              3DRender
              3DInput
              )
      
      add_executable("${PROJECT_NAME}_main" main.cpp)
      
      target_link_libraries("${PROJECT_NAME}_main"
              Qt5::Core
              Qt5::Gui
              Qt5::Widgets
              Qt5::3DCore
              Qt5::3DExtras
              Qt5::3DRender
              Qt5::3DInput
              )
      
      
      kshegunovK 1 Reply Last reply
      1
      • F Finn

        @kshegunov No, I completely reinstalled everything to the folder /opt/Qt-5.7 by following your instructions and those in the tutorial (https://wiki.qt.io/Install_Qt_5_on_Ubuntu). Before, I deleted everything but the result is the same. So far I used CLion2016 and now I also tried the QtCreator - still the same outcome.

        I also added some axes (x=red, y=green, z=blue), which are instantiated after the spheres.

        view 1
        view 2

        Other ideas?

        main.cpp

        #include <QGuiApplication>
        #include <Qt3DCore>
        #include <Qt3DRender>
        #include <Qt3DExtras>
        
        Qt3DCore::QEntity* createTestScene() {
        
          Qt3DCore::QEntity* root = new Qt3DCore::QEntity;
          Qt3DCore::QEntity* smallGreenSphere = new Qt3DCore::QEntity(root);
          Qt3DCore::QEntity* bigRedSphere = new Qt3DCore::QEntity(root);
        
        
          Qt3DExtras::QSphereMesh* bigMesh = new Qt3DExtras::QSphereMesh;
          bigMesh->setRadius(5);
          bigMesh->setRings(100);
          bigMesh->setSlices(20);
        
          Qt3DExtras::QSphereMesh* smallMesh = new Qt3DExtras::QSphereMesh;
          smallMesh->setRadius(2);
          smallMesh->setRings(100);
          smallMesh->setSlices(20);
        
          Qt3DExtras::QPhongMaterial* redMaterial = new Qt3DExtras::QPhongMaterial;
          redMaterial->setSpecular(Qt::white);
          redMaterial->setShininess(10);
          redMaterial->setAmbient(Qt::red);
        
          Qt3DExtras::QPhongMaterial* greenMaterial = new Qt3DExtras::QPhongMaterial;
          greenMaterial->setSpecular(Qt::white);
          greenMaterial->setShininess(10);
          greenMaterial->setAmbient(Qt::green);
        
        
          Qt3DCore::QTransform* transform =  new Qt3DCore::QTransform;
          transform->setTranslation(QVector3D(0,0,10));
        
          bigRedSphere->addComponent(redMaterial);
          bigRedSphere->addComponent(bigMesh);
        
          smallGreenSphere->addComponent(greenMaterial);
          smallGreenSphere->addComponent(smallMesh);
          smallGreenSphere->addComponent(transform);
        
          Qt3DCore::QEntity* xaxis = new Qt3DCore::QEntity(root);
          Qt3DCore::QEntity* yaxis = new Qt3DCore::QEntity(root);
          Qt3DCore::QEntity* zaxis = new Qt3DCore::QEntity(root);
        
          Qt3DExtras::QCylinderMesh* cylinderMesh = new Qt3DExtras::QCylinderMesh;
          cylinderMesh->setRadius(0.2);
          cylinderMesh->setLength(20);
          cylinderMesh->setRings(100);
          cylinderMesh->setSlices(20);
        
          Qt3DExtras::QPhongMaterial* blueMaterial = new Qt3DExtras::QPhongMaterial;
          blueMaterial->setSpecular(Qt::white);
          blueMaterial->setShininess(10);
          blueMaterial->setAmbient(Qt::blue);
        
          double pi = 3.14159265359;
          Qt3DCore::QTransform* xTransform = new Qt3DCore::QTransform();
          xTransform->setTranslation(QVector3D(10,0,0));
          xTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(0,0,1),90));
          Qt3DCore::QTransform* yTransform = new Qt3DCore::QTransform();
          yTransform->setTranslation(QVector3D(0,10,0));
          Qt3DCore::QTransform* zTransform = new Qt3DCore::QTransform();
          zTransform->setTranslation(QVector3D(0,0,10));
          zTransform->setRotation(QQuaternion::fromAxisAndAngle(QVector3D(1,0,0),90));
        
        
          xaxis->addComponent(cylinderMesh);
          xaxis->addComponent(redMaterial);
          xaxis->addComponent(xTransform);
          yaxis->addComponent(cylinderMesh);
          yaxis->addComponent(greenMaterial);
          yaxis->addComponent(yTransform);
          zaxis->addComponent(cylinderMesh);
          zaxis->addComponent(blueMaterial);
          zaxis->addComponent(zTransform);
        
          return root;
        }
        
        
        int main(int argc, char* argv[]) {
        
          QGuiApplication app(argc, argv);
          Qt3DExtras::Qt3DWindow view;
          Qt3DCore::QEntity* scene = createTestScene();
        
          // camera
          Qt3DRender::QCamera *camera = view.camera();
          camera->lens()->setPerspectiveProjection(45, 16./9., 0.1,1000.);
          camera->setPosition(QVector3D(45,15,45));
          camera->setViewCenter(QVector3D(0, 0, 0));
        
          // manipulator
          Qt3DExtras::QOrbitCameraController* manipulator = new Qt3DExtras::QOrbitCameraController(scene);
          manipulator->setLinearSpeed(50);
          manipulator->setLookSpeed(180);
          manipulator->setCamera(camera);
        
          view.setRootEntity(scene);
        
          view.show();
        
          return app.exec();
        }
        
        

        CMakeLists.txt

        cmake_minimum_required(VERSION 3.2)
        
        project(QtCreatorTest)
        
        find_package(Qt5 REQUIRED COMPONENTS
                Core
                Gui
                Widgets
                3DCore
                3DExtras
                3DRender
                3DInput
                )
        
        add_executable("${PROJECT_NAME}_main" main.cpp)
        
        target_link_libraries("${PROJECT_NAME}_main"
                Qt5::Core
                Qt5::Gui
                Qt5::Widgets
                Qt5::3DCore
                Qt5::3DExtras
                Qt5::3DRender
                Qt5::3DInput
                )
        
        
        kshegunovK Offline
        kshegunovK Offline
        kshegunov
        Moderators
        wrote on last edited by kshegunov
        #15

        @Finn
        This is really strange. I ran your code and it works perfectly fine for me (I use qmake with a kit for Qt 5.7 though). Here's what I see:

        And my project file is absolutely standard:

        QT       += core gui 3dcore 3drender 3dextras
        
        TARGET = balls-test
        TEMPLATE = app
        
        SOURCES += main.cpp
        

        [Edit: Fixed broken link]

        Read and abide by the Qt Code of Conduct

        F 1 Reply Last reply
        1
        • kshegunovK kshegunov

          @Finn
          This is really strange. I ran your code and it works perfectly fine for me (I use qmake with a kit for Qt 5.7 though). Here's what I see:

          And my project file is absolutely standard:

          QT       += core gui 3dcore 3drender 3dextras
          
          TARGET = balls-test
          TEMPLATE = app
          
          SOURCES += main.cpp
          

          [Edit: Fixed broken link]

          F Offline
          F Offline
          Finn
          wrote on last edited by
          #16

          @kshegunov I tried using qmake for building but again the same outcome.

          kshegunovK 1 Reply Last reply
          0
          • F Finn

            @kshegunov I tried using qmake for building but again the same outcome.

            kshegunovK Offline
            kshegunovK Offline
            kshegunov
            Moderators
            wrote on last edited by
            #17

            Honestly, I'd be surprised if there was a difference between using cmake and qmake. And to be completely frank I don't know what might be the cause of the problem. My current best advice is to either bring the question to the mailing list, where hopefully one of the developers of Qt3D will pick it up (but after you check there's no open bugs on this), or try and wait for some other suggestion from other of our members here.

            Kind regards.

            Read and abide by the Qt Code of Conduct

            F 1 Reply Last reply
            1
            • kshegunovK kshegunov

              Honestly, I'd be surprised if there was a difference between using cmake and qmake. And to be completely frank I don't know what might be the cause of the problem. My current best advice is to either bring the question to the mailing list, where hopefully one of the developers of Qt3D will pick it up (but after you check there's no open bugs on this), or try and wait for some other suggestion from other of our members here.

              Kind regards.

              F Offline
              F Offline
              Finn
              wrote on last edited by Finn
              #18

              I tried it on my private MacBook Pro with MacOS Sierra 10.12.1 and installed Qt5 via brew install qt5. The result is still the same. What on earth can be the reason that it is working for you guys and not for me? Do I need some other libraries or build options?

              1 Reply Last reply
              0
              • ? Offline
                ? Offline
                A Former User
                wrote on last edited by
                #19

                Sorry, as a noobie, I can't offer any insight, but I ran the code, and I'm getting the same as Finn. I'm on Qt 5.7 on Win 10.

                alt text

                Could it be CPU or GPU related? I'm on a 6coreAMD machine.

                F 1 Reply Last reply
                1
                • ? A Former User

                  Sorry, as a noobie, I can't offer any insight, but I ran the code, and I'm getting the same as Finn. I'm on Qt 5.7 on Win 10.

                  alt text

                  Could it be CPU or GPU related? I'm on a 6coreAMD machine.

                  F Offline
                  F Offline
                  Finn
                  wrote on last edited by
                  #20

                  @Ian-Bray Thank you for your reply, this was very helpful! I would suggest that someone more experienced than me should report this as a bug.

                  kshegunovK 1 Reply Last reply
                  0
                  • F Finn

                    @Ian-Bray Thank you for your reply, this was very helpful! I would suggest that someone more experienced than me should report this as a bug.

                    kshegunovK Offline
                    kshegunovK Offline
                    kshegunov
                    Moderators
                    wrote on last edited by kshegunov
                    #21

                    @Finn said in A weird bug? Why is there no spatial depth in my 3D scene?:

                    this was very helpfu

                    Indeed, it was.

                    I would suggest that someone more experienced than me should report this as a bug.

                    There's nothing to it, you just describe the problem and attach the screenshots and the code from upstairs as a minimal reproducible example (preferably with a simple project file). As for the problem itself it may be helpful if we can squeeze some more information out. I may be running a newer (or older) version of Qt compared to you. Can you both state the full version (with patch number). I'm running Qt 5.7.2 built from git some time ago on a Linux 4.8.11 kernel.

                    Read and abide by the Qt Code of Conduct

                    ? 1 Reply Last reply
                    0
                    • kshegunovK kshegunov

                      @Finn said in A weird bug? Why is there no spatial depth in my 3D scene?:

                      this was very helpfu

                      Indeed, it was.

                      I would suggest that someone more experienced than me should report this as a bug.

                      There's nothing to it, you just describe the problem and attach the screenshots and the code from upstairs as a minimal reproducible example (preferably with a simple project file). As for the problem itself it may be helpful if we can squeeze some more information out. I may be running a newer (or older) version of Qt compared to you. Can you both state the full version (with patch number). I'm running Qt 5.7.2 built from git some time ago on a Linux 4.8.11 kernel.

                      ? Offline
                      ? Offline
                      A Former User
                      wrote on last edited by
                      #22

                      @kshegunov

                      I'm using qt-opensource-windows-x86-mingw530-5.7.0 on Win 10, if I get a chance I'll try it on Linux later.

                      1 Reply Last reply
                      1
                      • ? Offline
                        ? Offline
                        A Former User
                        wrote on last edited by
                        #23

                        Sorry, this isn't going to be helpful. Just to report that both slabs of code crashed on Qt 5.7.1 GCC 64 on latest Mint.
                        Possibly due to lack of RAM. Not sure.

                        F 1 Reply Last reply
                        0
                        • ? A Former User

                          Sorry, this isn't going to be helpful. Just to report that both slabs of code crashed on Qt 5.7.1 GCC 64 on latest Mint.
                          Possibly due to lack of RAM. Not sure.

                          F Offline
                          F Offline
                          Finn
                          wrote on last edited by
                          #24

                          @Ian-Bray With Qt 5.7.1 the example works now perfectly fine for me.

                          kshegunovK ? 2 Replies Last reply
                          0
                          • F Finn

                            @Ian-Bray With Qt 5.7.1 the example works now perfectly fine for me.

                            kshegunovK Offline
                            kshegunovK Offline
                            kshegunov
                            Moderators
                            wrote on last edited by
                            #25

                            Then probably it's a bug that was fixed with the patch version in the meantime. Cheers!

                            Read and abide by the Qt Code of Conduct

                            ? 1 Reply Last reply
                            0
                            • F Finn

                              @Ian-Bray With Qt 5.7.1 the example works now perfectly fine for me.

                              ? Offline
                              ? Offline
                              A Former User
                              wrote on last edited by
                              #26

                              @Finn Thanks Finn. I'll update later!

                              1 Reply Last reply
                              0
                              • kshegunovK kshegunov

                                Then probably it's a bug that was fixed with the patch version in the meantime. Cheers!

                                ? Offline
                                ? Offline
                                A Former User
                                wrote on last edited by
                                #27

                                @kshegunov Must have been quite a big one. I ran the 3d Materials Example on 5.7.0 two days ago - it was horrible. I updated to 5.7.1 yesterday and ran it again - works perfect now.

                                kshegunovK 1 Reply Last reply
                                0
                                • ? A Former User

                                  @kshegunov Must have been quite a big one. I ran the 3d Materials Example on 5.7.0 two days ago - it was horrible. I updated to 5.7.1 yesterday and ran it again - works perfect now.

                                  kshegunovK Offline
                                  kshegunovK Offline
                                  kshegunov
                                  Moderators
                                  wrote on last edited by
                                  #28

                                  Well, 5.7.0 was Qt3D's first official release, and the code hasn't matured as much as the other modules, so some bumps along the road are expected. My biggest beef with Qt3D actually is its very thin documentation, but I'm sure that'll improve with time.:)

                                  Read and abide by the Qt Code of Conduct

                                  1 Reply Last reply
                                  1
                                  • F Finn

                                    I want to use Qt3D within Qt5.7 to plot a 3D scene (a chemical molecule) which I want to rotate.
                                    The problem is that my 3D objects are not displayed according to their spatial positioning. The last created QEntity is always in the foreground, regardless of how I rotate the camera.
                                    In the minimum working example below, the QEntity smallGreenSphere is always in the foreground even though it is spatially positioned behind bigRedSphere in the default view specified in the camera settings.
                                    To rephrase the problem: My 3D scene has no depth.

                                    Please note that smallGreenSphere is instantiated after bigRedSphere in the main.cpp file shown below:

                                    #include <QGuiApplication>
                                    #include <Qt3DCore>
                                    #include <Qt3DRender>
                                    #include <Qt3DExtras>
                                    
                                    Qt3DCore::QEntity* createTestScene() {
                                    
                                      Qt3DCore::QEntity* root = new Qt3DCore::QEntity;
                                      Qt3DCore::QEntity* bigRedSphere = new Qt3DCore::QEntity(root);
                                      Qt3DCore::QEntity* smallGreenSphere = new Qt3DCore::QEntity(root);
                                    
                                      Qt3DExtras::QSphereMesh* bigMesh = new Qt3DExtras::QSphereMesh;
                                      bigMesh->setRadius(5);
                                      bigMesh->setRings(100);
                                      bigMesh->setSlices(20);
                                    
                                      Qt3DExtras::QSphereMesh* smallMesh = new Qt3DExtras::QSphereMesh;
                                      smallMesh->setRadius(2);
                                      smallMesh->setRings(100);
                                      smallMesh->setSlices(20);
                                    
                                      Qt3DExtras::QPhongMaterial* redMaterial = new Qt3DExtras::QPhongMaterial;
                                      redMaterial->setSpecular(Qt::white);
                                      redMaterial->setShininess(10);
                                      redMaterial->setAmbient(Qt::red);
                                    
                                      Qt3DExtras::QPhongMaterial* greenMaterial = new Qt3DExtras::QPhongMaterial;
                                      greenMaterial->setSpecular(Qt::white);
                                      greenMaterial->setShininess(10);
                                      greenMaterial->setAmbient(Qt::green);
                                    
                                      Qt3DCore::QTransform* transform =  new Qt3DCore::QTransform;
                                      transform->setTranslation(QVector3D(0,0,10));
                                    
                                      bigRedSphere->addComponent(redMaterial);
                                      bigRedSphere->addComponent(bigMesh);
                                    
                                      smallGreenSphere->addComponent(greenMaterial);
                                      smallGreenSphere->addComponent(smallMesh);
                                      smallGreenSphere->addComponent(transform);
                                    
                                      return root;
                                    }
                                    
                                    
                                    int main(int argc, char* argv[]) {
                                      
                                      QGuiApplication app(argc, argv);
                                      Qt3DExtras::Qt3DWindow view;
                                      Qt3DCore::QEntity* scene = createTestScene();
                                    
                                      // camera
                                      Qt3DRender::QCamera *camera = view.camera();
                                      camera->lens()->setPerspectiveProjection(45, 16./9., 0.1,1000.);
                                      camera->setPosition(QVector3D(30., 0, 60.));
                                      camera->setViewCenter(QVector3D(0, 0, 0));
                                    
                                      // manipulator
                                      Qt3DExtras::QOrbitCameraController* manipulator = new Qt3DExtras::QOrbitCameraController(scene);
                                      manipulator->setLinearSpeed(50);
                                      manipulator->setLookSpeed(180);
                                      manipulator->setCamera(camera);
                                    
                                    view.setRootEntity(scene);
                                    
                                    view.show();
                                    
                                    return app.exec();
                                    }
                                    

                                    This results in the following scene: Image of the result
                                    Please note that I did not rotate anything manually and that this is the output of the code above.

                                    If I now swap the order of instantiation in createTestScene() by

                                    Qt3DCore::QEntity* smallGreenSphere = new Qt3DCore::QEntity(root);
                                    Qt3DCore::QEntity* bigRedSphere = new Qt3DCore::QEntity(root);
                                    

                                    so that bigRedSphere is now instantiated after smallGreenSphere, the bigRedSphere is always in the foreground and the resulting scene (again without manual rotation) looks like this: Image of the result

                                    This proves that the order of instantiation determines what sphere is displayed in the foreground.

                                    How can I obtain the correct 3D view regardless of the order of instantiation? Do I have to use some different rendering technique?
                                    Thanks in advance for your help and please consider that I am new to Qt, Qt3D, and rendering in your answer.

                                    Pablo J. RoginaP Offline
                                    Pablo J. RoginaP Offline
                                    Pablo J. Rogina
                                    wrote on last edited by
                                    #29

                                    For further reference this issue seems solved as described in this post.

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