Qt3D how to insert entities instancied in cpp to a QML Framegraph?

[IanMoone]

I have no issue to insert an Entity instancied in cpp containing everythings (models and framegraph) into a qml Scene3D, but I am trying to split it in a way to be able to declare the framegraph in qml and instancing models in cpp.

Here is my QML file :

import QtQuick 2.5
import Qt3D.Core 2.0
import Qt3D.Render 2.0
import QtQuick.Scene3D 2.0

Scene3D {
	anchors.fill: parent
//    entity: scene3DRootEntity

    Entity {
        id: emptyEntity
    }

    Entity {
        Camera {
            id: camera
            projectionType: CameraLens.PerspectiveProjection
            fieldOfView: 60
            aspectRatio: 4.0 / 3.0
            nearPlane : 0.1
            farPlane : 1000.0
            position: Qt.vector3d(60.0, 40.0, 100.0)
            upVector: Qt.vector3d(0.0, 1.0, 0.0)
            viewCenter: Qt.vector3d(0.0, 0.0, 0.0)
        }

        Configuration  {
            controlledCamera: camera
        }

        Viewport {
              id: viewport
              rect: Qt.rect(0.0, 0.0, 1.0, 1.0)
              clearColor: Qt.rgba(64 / 255, 128 / 255, 128 / 255, 255 / 255)

              CameraSelector {
                  id : cameraSelector
                  camera: camera
                  ClearBuffer {
                      buffers : ClearBuffer.ColorDepthBuffer
                  }
              }
          }

          components: [
              FrameGraph {
                  id: framgraph
                  activeFrameGraph: viewport
              }
          ]

/*        Scene3D {      // No error, but the model isn't visible
            entity: {
                if (typeof (elements) != 'undefined')
                    return elements
                return emptyEntity
            }
        }*/
        Entity {
            childNodes: {    // Isn't exposed to qml, is it a bug? Because we can't instanciate a Node too. I have also tried with components, but I am not sure that it is valid to add an entity as component
                if (typeof (elements) != 'undefined')
                    return [elements]
                return [emptyEntity]
            }
        }
    }
}

And here is the cpp part :

	void    Scene::initialize()
	{
		mRootEntity = new QEntity();
		mElementsEntity = new QEntity(/*mRootEntity*/);

		qmlContext->setContextProperty("scene3DRootEntity", mRootEntity);
		qmlContext->setContextProperty("elements", mElementsEntity);

		mRootEntity->setObjectName(QStringLiteral("rootEntity"));

		QEntity*	objectEntity = new QEntity(mElementsEntity);

		loadModel(QString::fromUtf8(core::ResourceManager::singleton()->getResource("/3D/Model/abri_jardin.mod").c_str()), objectEntity);
//		loadModel(QString::fromUtf8(core::ResourceManager::singleton()->getResource("/3D/Model/abreuvoir_oiseaux.mod").c_str()), objectEntity);

		// Object Transform
		Qt3DCore::QTransform *objectTransforms = new Qt3DCore::QTransform();

		objectTransforms->setTranslation(QVector3D(0.0f, 0.0f, 0.0f));
		objectTransforms->setScale(20.0f);
		objectEntity->addComponent(objectTransforms);

		// Camera
		Qt3DCore::QCamera *cameraEntity = new Qt3DCore::QCamera(mRootEntity);
		cameraEntity->setObjectName(QStringLiteral("cameraEntity"));

		cameraEntity->lens()->setPerspectiveProjection(60.0f, 4.0f / 3.0f, 0.1f, 1000.0f);
		cameraEntity->setPosition(QVector3D(60, 40, 100.0f));
		cameraEntity->setViewCenter(QVector3D(0, 0, 0));
		cameraEntity->setUpVector(QVector3D(0, 1, 0));
//            input->setCamera(cameraEntity);

		QFrameGraph*		frameGraph = new QFrameGraph();
		QTechniqueFilter*	techniqueFilter = new QTechniqueFilter();
		QViewport*			viewport = new QViewport(techniqueFilter);
		QClearBuffer*		clearBuffer = new QClearBuffer(viewport);
		QCameraSelector*	cameraSelector = new QCameraSelector(clearBuffer);
		QCullFace*			cullFace = new QCullFace(cameraSelector);
		QRenderPassFilter*	renderPassFilter = new QRenderPassFilter(cullFace);

		// TechiqueFilter and renderPassFilter are not implement yet
		viewport->setRect(QRectF(0, 0, 1, 1));
		viewport->setClearColor(QColor(64, 128, 128));
		clearBuffer->setBuffers(QClearBuffer::ColorDepthBuffer);
		cameraSelector->setCamera(cameraEntity);
		frameGraph->setActiveFrameGraph(techniqueFilter);
		cullFace->setEnabled(false);

		// Setting the FrameGraph
		mRootEntity->addComponent(frameGraph);
	}

Does someone do something similar?