Assigning category, collision and contact bit mask to reference nodes in code - swift

Question

I have a level based game, so I am using the Xcode Scene Editor for level creation, but am having troubles detecting collision between objects, that were created in separate scenes and dragged in game scenes as reference nodes.
It seems that if I try to create the physics body of an object, that is used as a reference node in that .scn file where I created it, that physics body is not being referenced to nodes in the game scene, but the properties that were created directly in Scene Editor are.
If I try and set the physics body of each node that is actually a reference node via code, it does set it (the physics body is not nil), but the collision is not detected.
This is the code, where I set the physics bodies:
// player (I want to be notified when player collides with any walls)
playerNode = level1Scene.rootNode.childNodeWithName("playerNode", recursively: true)!
playerNode.physicsBody = SCNPhysicsBody(type: .Dynamic, shape: nil)
playerNode.physicsBody?.affectedByGravity = false
playerNode.physicsBody?.categoryBitMask = PhysicsCategory.Player.rawValue
playerNode.physicsBody?.collisionBitMask = PhysicsCategory.Wall.rawValue
playerNode.physicsBody?.contactTestBitMask = PhysicsCategory.Wall.rawValue
//wall from separate .scn file
let wallScene = SCNScene(named: "wallObject.scn")
let wall = wallScene!.rootNode.childNodeWithName("wall", recursively: true)!
wall.physicsBody = SCNPhysicsBody(type: .Kinematic, shape: nil)
wall.physicsBody?.categoryBitMask = PhysicsCategory.Wall.rawValue
wall.physicsBody?.collisionBitMask = PhysicsCategory.Player.rawValue
wall.physicsBody?.contactTestBitMask = PhysicsCategory.Player.rawValue
// walls that are reference nodes of the wall and are located in game scene
let wall2 = level1Scene.rootNode.childNodeWithName("wallObject reference", recursively: true)!
wall2.physicsBody = SCNPhysicsBody(type: .Kinematic, shape: nil)
wall2.physicsBody?.categoryBitMask = PhysicsCategory.Wall.rawValue
wall2.physicsBody?.collisionBitMask = PhysicsCategory.Player.rawValue
wall2.physicsBody?.contactTestBitMask = PhysicsCategory.Player.rawValue
print(wall2.physicsBody!) // prints <SCNPhysicsBody: 0x7fe5f9dc75a0>
I am not contacted about any contacts, nor does the player physically collide with any wall on contact. I have conformed the class to the SCNPhysicsContactDelegate protocol:
extension GameViewController: SCNPhysicsContactDelegate {
func physicsWorld(world: SCNPhysicsWorld, didBeginContact contact: SCNPhysicsContact) {
playerNode.physicsBody?.velocity = SCNVector3Zero
print("player and wall collided")
}
}
and set the contact delegate to my game scene:
level1Scene.physicsWorld.contactDelegate = self
I have been trying to get this to work for two days now, with no success. When I was working with Sprite Kit, I could almost always find relevant posts about my problem and even when posting my question, I would get an answer. But Scene Kit is not as popular I guess and I can't find anything.
If you do know where I am wrong or how the collision could be detected in code, please tell me.

Answer 1

I cobbled together an example loosely based on the code you posted up, the only 'problem' is that it worked, in that the contact delegate is successfully called. The player geometry in this case is the SceneKit spaceship, and the wall2 is a SCNBox added into the other scene then dragged into the ship scene from Finder. I've included gravity, so the ship just falls onto the wall.
Do the objects bounce off each other, and it's just that your contact delegate isn't called? Or do the objects pass through each other. I'm also wondering how you move the player object to cause the contact?
import UIKit
import QuartzCore
import SceneKit
let colors = [UIColor.redColor(), UIColor.brownColor(), UIColor.cyanColor(), UIColor.greenColor(), UIColor.yellowColor(), UIColor.blueColor()]
enum PhysicsCategory:Int {
case Player = 2
case Wall = 4
}
extension GameViewController: SCNPhysicsContactDelegate {
func physicsWorld(world: SCNPhysicsWorld, didBeginContact contact: SCNPhysicsContact) {
playerNode.geometry?.firstMaterial?.diffuse.contents = colors[Int(arc4random_uniform(UInt32(colors.count)))]
print("player and wall collided")
}
}
class GameViewController: UIViewController {
var playerNode:SCNNode!
override func viewDidLoad() {
super.viewDidLoad()
// create a new scene
//let scene = SCNScene()
let scene = SCNScene(named: "art.scnassets/ship.scn")!
//playerNode = SCNNode(geometry: SCNBox(width: 1, height: 1, length: 1, chamferRadius: 0))
playerNode = scene.rootNode.childNodeWithName("ship", recursively: true)!
playerNode.geometry?.firstMaterial?.diffuse.contents = UIColor.redColor()
playerNode.physicsBody = SCNPhysicsBody(type: .Dynamic, shape: nil)
playerNode.physicsBody?.affectedByGravity = true
playerNode.physicsBody?.categoryBitMask = PhysicsCategory.Player.rawValue
playerNode.physicsBody?.collisionBitMask = PhysicsCategory.Wall.rawValue
playerNode.physicsBody?.contactTestBitMask = PhysicsCategory.Wall.rawValue
initPlayer()
//scene.rootNode.addChildNode(playerNode)
//let wall = SCNNode(geometry: SCNBox(width: 20, height: 0.25, length: 20, chamferRadius: 0))
let wallScene = SCNScene(named: "art.scnassets/wallObject.scn")
let wall = wallScene!.rootNode.childNodeWithName("wall", recursively: true)!
wall.physicsBody = SCNPhysicsBody(type: .Kinematic, shape: nil)
wall.physicsBody?.categoryBitMask = PhysicsCategory.Wall.rawValue
wall.physicsBody?.collisionBitMask = PhysicsCategory.Player.rawValue
wall.physicsBody?.contactTestBitMask = PhysicsCategory.Player.rawValue
//scene.rootNode.addChildNode(wall)
let wall2 = scene.rootNode.childNodeWithName("wallObject reference", recursively: true)!
wall2.physicsBody = SCNPhysicsBody(type: .Kinematic, shape: nil)
wall2.physicsBody?.categoryBitMask = PhysicsCategory.Wall.rawValue
wall2.physicsBody?.collisionBitMask = PhysicsCategory.Player.rawValue
wall2.physicsBody?.contactTestBitMask = PhysicsCategory.Player.rawValue
scene.physicsWorld.contactDelegate = self
// retrieve the SCNView
let scnView = self.view as! SCNView
scnView.playing = true
scnView.scene = scene
scnView.allowsCameraControl = true
scnView.autoenablesDefaultLighting = true
scnView.showsStatistics = true
scnView.backgroundColor = UIColor.lightGrayColor()
// add a tap gesture recognizer
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(_:)))
scnView.addGestureRecognizer(tapGesture)
}
func handleTap(gestureRecognize: UIGestureRecognizer) {
initPlayer()
}
func initPlayer() {
playerNode.position = SCNVector3Make(0, 12, 0)
playerNode.eulerAngles = SCNVector3Make(Float(drand48() * M_PI/2), Float(drand48() * M_PI/2), Float(drand48() * M_PI/2))
playerNode.physicsBody?.velocity = SCNVector3Zero
playerNode.physicsBody?.angularVelocity = SCNVector4Zero
}
}