ARkit Scene Kit Animations - arkit

Question

I'm building an app with ARkit and I'd like the user to have the ability to start and stop animations in the scene with the use of a button in the viewcontroller. However, I am having trouble finding an example of this code. Any pointers would be appreciated. For reference, my code is as follows for animating the dae file. I had a version working where I could stop the animation, but could not get it to restart. Thanks in advance.
func loadModels(atom: String) {
// Create a new scene
let scene = SCNScene(named: "art.scnassets/" + atom + ".scn")!
// Set the scene to the view
sceneViewAr?.scene = scene
let mainnode = scene.rootNode.childNode(withName: "mainnode", recursively: true)
mainnode?.runAction(SCNAction.rotateBy(x: 10, y: 0, z: 0, duration: 0))
let orbit = scene.rootNode.childNode(withName: "orbit", recursively: true)
orbit?.runAction(SCNAction.rotateBy(x: 0, y: 2 * 50, z: 0, duration: 100))
if let orbittwo = scene.rootNode.childNode(withName: "orbit2", recursively: true) {
orbittwo.runAction(SCNAction.rotateBy(x: 0, y: -2 * 50, z: 0, duration: 100))
}
if let orbitthree = scene.rootNode.childNode(withName: "orbit3", recursively: true) {
orbitthree.runAction(SCNAction.rotateBy(x: 0, y: 2 * 50, z: 0, duration: 100))
}
}

Answer 1

I dont think there is a way to pause and stop in the way that you want per se.
Having said this you can make use of the following SCNAction functions:
func action(forKey key: String) -> SCNAction?
func removeAction(forKey key: String)
Essentially you are going to have to stop and then recreate the actions again.
As such you could do something like so:
Create a variable under your class declaration for your SCNActions so you dont have to rewrite them every time e.g:
let rotateXAction = SCNAction.rotateBy(x: 10, y: 0, z: 0, duration: 10)
Then Create 2 functions one to add and the other to remove the actions e.g:
/// Adds An SCNAction To A Specified Node With A Key
///
/// - Parameters:
/// - action: SCNAction
/// - node: SCNNode
/// - key: String
func addAction(_ action: SCNAction, toNode node: SCNNode, forKey key: String){
node.runAction(action, forKey: key)
}
/// Removes An SCNAction For A Specified Node With A Key
///
/// - Parameters:
/// - action: SCNAction
/// - node: SCNNode,
/// - key: String
func removeActionFromNode(_ node: SCNNode, forKey key: String){
node.removeAction(forKey: key)
}
Which you could then test like so:
/// Tests Whether The `SCNActions` Can Be Stated & Stopped
func testActions(){
//1. Create An Array Of Colours
let colours: [UIColor] = [.red, .green, .blue, .orange, .purple, .black]
//2. Create An Array Of Face Materials
var faceArray = [SCNMaterial]()
//3. Create An SCNNode With An SCNBox Geometry
let firstNode = SCNNode(geometry: SCNBox(width: 0.1, height: 0.1, length: 0.1, chamferRadius: 0))
for faceIndex in 0..<colours.count{
let material = SCNMaterial()
material.diffuse.contents = colours[faceIndex]
faceArray.append(material)
}
firstNode.geometry?.materials = faceArray
//4. Add It To The Scene
self.augmentedRealityView.scene.rootNode.addChildNode(firstNode)
firstNode.position = SCNVector3(0 , 0, -1)
//5. Run The Action
addAction(rotateXAction, toNode: firstNode, forKey: "rotateX")
//6. Stop It After 4 Seconds
DispatchQueue.main.asyncAfter(deadline: .now() + 4) {
self.removeActionFromNode(firstNode, forKey: "rotateX")
}
//7. Start It Again After 8
DispatchQueue.main.asyncAfter(deadline: .now() + 8) {
self.addAction(self.rotateXAction, toNode: firstNode, forKey: "rotateX")
}
}
In your context you can easily tweak these functions to apply for a specific IBAction etc.
This is just a starter and in no way a refactored or refined example, however it should point you in the right direction...