Two ways to load qml 3d scene

//main.cpp

#include <Qt3DQuickExtras/qt3dquickwindow.h>
#include <QGuiApplication>
#include <QQuickView>

int main(int argc, char* argv[])
{
    QGuiApplication app(argc, argv);

   // Qt3DExtras::Quick::Qt3DQuickWindow view;  //3D视图场景，用此场景不需要Scene3D控件

    QQuickView view; //普通2D视图
    view.setSource(QUrl("../main.qml"));
    view.show();

    return app.exec();
}

//main.qml

import QtQuick 2.0
import QtQuick.Scene3D 2.0
import Qt3D.Core 2.0
import Qt3D.Render 2.0
import Qt3D.Input 2.0
import Qt3D.Extras 2.0

Item {
    width: 800
    height: 600

    Scene3D{
        anchors.fill: parent

        Entity {
            id: sceneRoot

            Camera {
                id: camera
                projectionType: CameraLens.PerspectiveProjection
                fieldOfView: 45
                aspectRatio: 16/9
                nearPlane : 0.1
                farPlane : 1000.0
                position: Qt.vector3d( 0.0, 0.0, -40.0 )
                upVector: Qt.vector3d( 0.0, 1.0, 0.0 )
                viewCenter: Qt.vector3d( 0.0, 0.0, 0.0 )
            }

            OrbitCameraController {
                camera: camera
            }

            components: [
                RenderSettings {
                    activeFrameGraph: ForwardRenderer {
                        clearColor: Qt.rgba(0, 0.5, 1, 1)
                        camera: camera
                    }
                },
                // Event Source will be set by the Qt3DQuickWindow
                InputSettings { }
            ]

            PhongMaterial {
                id: material
            }

            TorusMesh {
                id: torusMesh
                radius: 5
                minorRadius: 1
                rings: 100
                slices: 20
            }

            TorusMesh {
                id: torusMesh2
                radius: 10
                minorRadius: 2
                rings: 100
                slices: 20
            }

            Transform {
                id: torusTransform
                scale3D: Qt.vector3d(1.5, 1, 0.5)
                rotation: fromAxisAndAngle(Qt.vector3d(1, 0, 0), 45)
            }

            Entity {
                id: torusEntity
                components: [ torusMesh, material, torusTransform ]
            }

            SphereMesh {
                id: sphereMesh
                radius: 3
            }

            Transform {
                id: sphereTransform
                property real userAngle: 0.0
                matrix: {
                    var m = Qt.matrix4x4();
                    m.rotate(userAngle, Qt.vector3d(0, 1, 0));
                    m.translate(Qt.vector3d(20, 0, 0));
                    return m;
                }
            }

           NumberAnimation {
                target: sphereTransform
                property: "userAngle"
                duration: 10000
                from: 0
                to: 360

                loops: Animation.Infinite
                running: true
            }

            Entity {
                id: sphereEntity
                components: [ sphereMesh, material, sphereTransform ]
            }
        }

    }



}