Hello-Window.md

Hello Window

Scene3D is the QtQuick component to bridge QtQuick and Qt3D, Scene3D is a QQuickItem, its Component3D children can be rendered in the 3D scene.

There are several ways to create Qt3D scene (https://forum.qt.io/topic/68781/scene3d-vs-qt3dquickwindow-pictures-differ/2)

1. Qt3DQuickWindow + Component3D components for pure Qt3D app:

   Qt3DExtras::Quick::Qt3DQuickWindow view;
   view.setSource(QUrl("qrc:/main.qml"));
   view.show();

   Input is auto captured by default for Qt3DQuickWindow. Where main.qml starts with root entity:

   Entity {
       id: sceneRoot
       ...
   }

2. QQuickView with QtQuick default GL context + Scene3D:

   QQuickView view;
   view.setResizeMode(QQuickView::SizeRootObjectToView);
   view.setSource(QUrl("qrc:/main.qml"));
   view.show();

   Where main.qml starts with QQuickItem:

   Item {
       id: view
       ...
       Scene3D {
       id: scene
       }
   }

3. QQuickView with different GL context + Scene3D:

   QSurfaceFormat format;
   if (QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGL) {
       format.setVersion(3, 3);
       format.setProfile(QSurfaceFormat::CoreProfile);
   }
   format.setDepthBufferSize(24);
   format.setStencilBufferSize(8);
   format.setSamples(4);
   
   
   QQuickView view;
   view.setResizeMode(QQuickView::SizeRootObjectToView);
   view.setSource(QUrl("qrc:/main.qml"));
   view.show();

   Where main.qml starts with QQuickItem, advance GL context is available:

   Item {
       id: view
       ...
       Scene3D {
           id: scene
       ...
       /* GL33 Shaders*/
       ...
       }
   }

4. QQmlApplicationEngine with different GL context + Scene3D:

   QSurfaceFormat format;
   if (QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGL) {
       format.setVersion(4, 3);
       format.setProfile(QSurfaceFormat::CoreProfile);
   } else if (QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGLES) {
       format.setVersion(2, 0);
   }
   
   
   format.setAlphaBufferSize(0);
   format.setDepthBufferSize(0);
   format.setRenderableType(QSurfaceFormat::OpenGL);
   format.setSamples(4);
   format.setStencilBufferSize(0);
   format.setSwapBehavior(QSurfaceFormat::TripleBuffer);
   format.setSwapInterval(0);
   
   
   QSurfaceFormat::setDefaultFormat(format);
   
   
   QQmlApplicationEngine engine;
   engine.load(QUrl(QLatin1String("qrc:/main.qml")));

   Where main.qml starts with Window, advance GL context is available:

   ApplicationWindow {
       id: app
       ...
       Scene3D {
           id: scene
       ...
       /* GL33 Shaders*/
       ...
       }
   }

   That's how our application starts with.

Tips:

• To append QtQuick Item on Scene3D, use property children

hellowindow

1. Use QSurfaceFormat to set global GL context:

   

2. Set a Viewport to activeFrameGraph making render flow complete:

   

hellowindow2

1. Viewport is a FrameGraphNode, ClearBuffers is another one with clearbuffer setting, note buffers is usually set to ClearBuffers.ColorDepthBuffer even no depth order in your scene (see Hello-Triangle):