In the following code, mapTo3DScene() will fail with the error:

QML View3D: Cannot resolve scene position without a camera assigned!
qml: pos3D: QVector3D(0, 0, 0)

View3D {

    id: view
    OrthographicCamera{ 
        id: mainCamera 
        z: 200 
    }
    Node {
        .....
    }
    MouseArea { 
        anchors.fill: view  
        onMouseXChanged: { 
            var pos3D = view.mapTo3DScene(Qt.vector3d(mouseX, mouseY, 0))
            console.log("pos3D: "+pos3D) 
        }
}

Note that explicit setting the camera in View3D like this:

camera: OrthographicCamera{

            id: mainCamera

            z: 200

        }
 

will make mapTo3DScene() work properly, but then View3D content will fail to be displayed.

I notice that adding view.update() to onMouseXChanged will make View3D content to be display, but this is ugly since it will only show content on mouse move. I tried calling view.update() on Component.complet but this fails.

The attached example shows a red Sphere Model, be sure to compile commenting / uncommentig line 27 in main.qml, where the OrtographicCamera is explicitly set.

• camera explicit set: mapTo3DScene() works but View3D content display fails

• camera not explicit set: mapTo3DScene() fails, but View3D content display works