                         object.addChild(obj)
                     }
                     
-                    // set parent??
+                // set parent??
                 case .Camera:
                     if let ref = objRef {
                         let cam = container.resolve(MDLCamera.self, name: ref)!

            vertexDesc = MDLVertexDescriptor(vertexDescriptor: parentDesc)
        }
        
        let attributeSelector = SpectraXMLNodeType.VertexAttribute.rawValue
        for (idx, el) in elem.css(attributeSelector).enumerate() {
            if let ref = el.attributes["ref"] {
                let vertexAttr = container.resolve(MDLVertexAttribute.self, name: ref)!

public class SpectraXMLVertexDescriptorNode: SpectraXMLNode {
    public typealias NodeType = MDLVertexDescriptor
    
    public func parse(container: Container, elem: XMLElement, options: [String : Any] = [:]) -> NodeType {
        var vertexDesc = MDLVertexDescriptor()
        
        // if user specified a parent descriptor, find it and copy it
