Adding child nodes to terraine nodes on ARSCNView

[paulsUsername]

I have tried a good few different combinations but once I'm on ARSCNView I can't seem to add any child nodes. Even If I don't use terrainNode.convertPosition and just try to add a child to the root node, nothing shows.

The child is being added as if I check the count of arView?.scene.rootNode.childNodes it is increasing every time I add a child node but visually I see nothing.

I am adding them like this with a button once everything loaded:

`
let endSphere = SCNNode(geometry: SCNSphere(radius: 100.0))
endSphere.geometry?.firstMaterial?.diffuse.contents = UIColor.red
endSphere.position = (arView?.scene.rootNode.position)!

    arView?.scene.rootNode.addChildNode(endSphere)
    
    print(arView?.scene.rootNode.childNodes.count)`

[natalia-osa]

Can you please try this:

let node = SCNNode(geometry: SCNSphere(radius: 100.0))
node.geometry?.firstMaterial?.diffuse.contents = .red
let position = positionForLocation(CLLocationValue)
node.position = convertPosition(position, to: self.terrainNode)
terrainNode.addChildNode(firstNode)

Or you can simply use my PR to do it easily (#24) by using terrainNode.projectedSphere method.