         let y = cos(rotationOffset) * radius
         
         let sphereNode =  SCNNode(geometry: spereGeometry)
-        sphereNode.position = SCNVector3Make(Float(x), Float(y), 0.0)
+        sphereNode.position = SCNVector3Make(Float(x), Float(y), zplane / 3)
         
         return sphereNode
     }

        particleSceneView.scene = scene
    }

    func createParticlesceneNode (particleSet: ParticleSet) -> SCNNode {
//      create center Node
        let spereGeometry = SCNSphere(radius: 0.2)
        spereGeometry.firstMaterial!.diffuse.contents = UIColor.blackColor()

    func sceneSetup() {
        // 1
        let scene = SCNScene()

        var randomSets = Array<ParticleSet>()
        for i in 1...10 {
            let particleSet = randomParticleSet()
            randomSets.append(particleSet)
        }
        scene.rootNode.addChildNode(createPartcleSceneNodeFromSets(randomSets) )

        particleSceneView.autoenablesDefaultLighting = true
        particleSceneView.allowsCameraControl = true
