How can I dynamically track SCNNodes in a scene for removal? - ios

Question

Obligatory: first time writing an app, relevant code is below. My code runs mostly as I want it to, but does not achieve my goal of dynamic object tracking.
I'm using Swift and Scenekit to build a simple puzzle game, similar to a 3d-version of candy crush.
I have a class Cube that extends SCNNode. On initialization, this class will randomly draw a 5x5 cube of SCNBoxes with each box being red, green, or blue (all 6 sides of a box are 1 color).
The goal of the game is to get the highest score by removing "chains" of SCNBoxes of like-colors. When a chain is removed, cubes should recognize gravity and drop to fill in the voids created by the removed-chain. This is where I need to dynamically track position. As the cubes fall into the gaps, their neighbors change.
My approach: build a struct CubeDetails that has properties var color: String and var location: SCNVector3. Next, build a dictionary masterCubeDict = [SCNNode: CubeDetails] that has all of the cubes of 1 color (the color is provided by a hittestresult).
Every time a user taps a cube, grab its color, refresh the masterCubeDict, and then use math on the SCNVector3 position to determine which cubes are neighbors.
I think my algorithm for finding 'cube neighbors' using math on the scnvector3 is where I'm off. There must be a better way for scenekit nodes to identity/find each other, right?
Also -- I would like the physics of the cubes to let them fall and have no bounce/sliding at all. They should only move straight up/down. Collisions should never happen. I thought I implemented that properly through friction, restituion, and mass of the cubes but I'm not getting the outcome I want.
class Cube
import SceneKit
class Cube : SCNNode {
let cubeWidth:Float = 0.95
let spaceBetweenCubes:Float = 0.05
var cubecolor:UIColor = UIColor.black
var masterCubeDict: [SCNNode: CubeDetails] = [:]
struct CubeDetails {
var color:String
var position:SCNVector3
}
override init() {
super.init()
let cubeOffsetDistance = self.cubeOffsetDistance()
var cubeColorString: String = ""
var xPos:Float = -cubeOffsetDistance
var yPos:Float = -cubeOffsetDistance
var zPos:Float = -cubeOffsetDistance
let xFloor:Float = -1.5
let yFloor:Float = -1.5
let zFloor:Float = -1.5
let floorGeo = SCNBox(width: 20, height: 0, length: 20, chamferRadius: 0)
let floor = SCNNode(geometry: floorGeo)
floor.position = SCNVector3(x: xFloor, y: yFloor, z: zFloor)
floor.name = "floor"
floor.opacity = 0.0
floor.physicsBody = SCNPhysicsBody(type: .kinematic, shape: nil)
floor.physicsBody?.collisionBitMask = 1
floor.physicsBody?.friction = 1.0
self.addChildNode(floor)
for _ in 0..<5 {
for _ in 0..<5 {
for _ in 0..<5 {
let cubeGeometry = SCNBox(width: CGFloat(cubeWidth), height: CGFloat(cubeWidth), length: CGFloat(cubeWidth), chamferRadius: 0)
let material = SCNMaterial()
material.diffuse.contents = randomColor()
//unwrap material (type any) and cast to uicolor for switch
if let unwrapColor: UIColor = material.diffuse.contents as? UIColor {
switch unwrapColor {
case UIColor.red:
cubeColorString = "red"
case UIColor.green:
cubeColorString = "green"
case UIColor.blue:
cubeColorString = "blue"
default:
cubeColorString = "black"
}
} else { print("Error unwrapping color") }
cubeGeometry.materials = [material, material, material, material, material, material]
let cube = SCNNode(geometry: cubeGeometry)
cube.name = cubeColorString
cube.physicsBody = SCNPhysicsBody(type: .dynamic, shape: nil)
cube.physicsBody?.restitution = 0.0
cube.physicsBody?.isAffectedByGravity = true
cube.physicsBody?.mass = 25.0
cube.physicsBody?.friction = 1.0
cube.physicsBody?.collisionBitMask = 1
cube.position = SCNVector3(x: xPos, y: yPos, z: zPos)
let details = CubeDetails(color: cubeColorString, position: cube.position)
//add cube details to the master dict
masterCubeDict[cube] = details
//print(masterCubeDict)
xPos += cubeWidth + spaceBetweenCubes
self.addChildNode(cube)
}
xPos = -cubeOffsetDistance
yPos += cubeWidth + spaceBetweenCubes
}
xPos = -cubeOffsetDistance
yPos = -cubeOffsetDistance
zPos += cubeWidth + spaceBetweenCubes
}
}
private func cubeOffsetDistance()->Float {
return (cubeWidth + spaceBetweenCubes) / 2
}
private func randomColor() -> UIColor{
var tmpColor: UIColor
let num = Int.random(in:0...2)
switch num {
case 0:
tmpColor = UIColor.red
case 1:
tmpColor = UIColor.blue
case 2:
tmpColor = UIColor.green
default:
tmpColor = UIColor.black
}
return tmpColor
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
GameViewController
import UIKit
import QuartzCore
import SceneKit
var myMasterCubeDict: [SCNNode: Cube.CubeDetails] = [:]
class GameViewController: UIViewController {
let gameCube = Cube()
override func viewDidLoad() {
super.viewDidLoad()
// create a new scene
// let scene = SCNScene(named: "art.scnassets/ship.scn")!
let scene = SCNScene()
// create and add a camera to the scene
let cameraNode = SCNNode()
cameraNode.camera = SCNCamera()
scene.rootNode.addChildNode(cameraNode)
// place the camera
cameraNode.position = SCNVector3(x: 2, y: 0, z: 20)
// create and add a light to the scene
let lightNode = SCNNode()
lightNode.light = SCNLight()
lightNode.light!.type = .omni
lightNode.position = SCNVector3(x: 0, y: 10, z: 10)
scene.rootNode.addChildNode(lightNode)
// create and add an ambient light to the scene
let ambientLightNode = SCNNode()
ambientLightNode.light = SCNLight()
ambientLightNode.light!.type = .ambient
ambientLightNode.light!.color = UIColor.darkGray
scene.rootNode.addChildNode(ambientLightNode)
// init cube
myMasterCubeDict = gameCube.masterCubeDict
scene.rootNode.addChildNode(gameCube)
// retrieve the SCNView
let scnView = self.view as! SCNView
// set the scene to the view
scnView.scene = scene
// allows the user to manipulate the camera
scnView.allowsCameraControl = true
// show statistics such as fps and timing information
scnView.showsStatistics = true
// configure the view
scnView.backgroundColor = UIColor.black
// add a tap gesture recognizer
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(handleTap(_:)))
scnView.addGestureRecognizer(tapGesture)
}
#objc
func handleTap(_ gestureRecognize: UIGestureRecognizer) {
// retrieve the SCNView
let scnView = self.view as! SCNView
// check what nodes are tapped
let p = gestureRecognize.location(in: scnView)
let hitResults = scnView.hitTest(p, options: [:])
// check that we clicked on at least one object
if hitResults.count > 0 {
// retrieved the first clicked object
let result = hitResults[0]
//get dict of same-color node
var dictOfSameColor = findAndReturnChain(boi: result.node)
// print(dictOfSameColor)
var finalNodes: [SCNNode] = [result.node]
var resFlag = 1
repeat {
var xSame: Bool = false
var ySame: Bool = false
var zSame: Bool = false
resFlag = 0
for node in finalNodes {
// var nodeX = node.position.x
for (key, value) in dictOfSameColor {
if(abs(node.position.x - value.position.x) < 0.7) {
xSame = true
}
if(abs(node.position.y - value.position.y) < 0.7) {
ySame = true
}
if(abs(node.position.z - value.position.z) < 0.7) {
zSame = true
}
//print("X-val: \(xDif) \nY-val: \(yDif) \nZ-val: \(zDif) \nColor: \(key.name) \n\n\n\n")
if (xSame && ySame ) {
if !(zSame) {
if (abs((node.position.z-value.position.z)) < 2) {
finalNodes.append(key)
dictOfSameColor.removeValue(forKey: key)
resFlag = 1
}
}
}
if (xSame && zSame) {
if !(ySame) {
if (abs((node.position.y-value.position.y)) < 2) {
finalNodes.append(key)
dictOfSameColor.removeValue(forKey: key)
resFlag = 1
}
}
}
if (ySame && zSame) {
if !(xSame) {
if (abs((node.position.x-value.position.x)) < 2) {
finalNodes.append(key)
dictOfSameColor.removeValue(forKey: key)
resFlag = 1
}
}
}
xSame = false
ySame = false
zSame = false
}
}
//print(finalNodes)
} while resFlag == 1
//print(finalNodes)
for node in finalNodes {
if node.name != "floor" {
node.removeFromParentNode()
}
}
//IMPLEMENT: Reset dicts to current state of the cube
myMasterCubeDict = updateMasterCubeDict(cube: gameCube)
dictOfSameColor.removeAll()
}
}
func findAndReturnChain(boi: SCNNode) -> [SCNNode:Cube.CubeDetails] {
var ret: [SCNNode:Cube.CubeDetails] = [:]
//find cubes with the same color
for (key, value) in myMasterCubeDict {
if value.color == boi.name {
ret[key] = value
}
}
return ret
}
func updateMasterCubeDict(cube: Cube) -> [SCNNode:Cube.CubeDetails] {
myMasterCubeDict.removeAll()
var newNode: SCNNode = SCNNode()
var newDetails = Cube.CubeDetails(color: "", position: SCNVector3Zero)
cube.enumerateChildNodes { (cube, stop) in
newNode = cube
if let newName = cube.name {
newDetails.color = newName
}
newDetails.position = cube.position
myMasterCubeDict[newNode] = newDetails
}
return myMasterCubeDict
}
override var shouldAutorotate: Bool {
return true
}
override var prefersStatusBarHidden: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
if UIDevice.current.userInterfaceIdiom == .phone {
return .allButUpsideDown
} else {
return .all
}
}
}

Answer 1

I did a game somewhat like this. You could probably get the math to work, but the way I did it was to map out each node and have an array containing its adjacent nodes. Doing it this way, I'm sure that when I remove a node and loop through its adjacent[array] nodes, then I got the right ones.
I don't subclass SCNNodes - some do, but I create the class I want that contains info about my node - I add the node to Scenekit there, that's separates the actual node from other work I may want to do with the class. Some nodes have a lot of detail that I may want to manage separately (multiple particle systems, movements, etc). Then I just keep my classes of nodes in an array and each class has direct access to it's own node.
Sorry - I don't know about the bounce, there are a lot of choices with the physics engine.