I have been working on a game in SceneKit which involves a plane that the user can control using the arrow keys. The plane can fly, but the arrow keys have no effect on the plane. When I run a test to see if the arrow key function is working I can see that the arrow keys are effectively changing the speed of the plane, but the plane does not increase or decrease speed. Here is the code:
import SceneKit
import QuartzCore
class GameViewController: NSViewController {
var height = 0
var speed = 0 //I should be able to change this value by pressing the up arrow key during the simulation
override func keyDown(with theEvent: NSEvent) {
if(theEvent.keyCode == 123){//left
}
if(theEvent.keyCode == 124){//right
}
if(theEvent.keyCode == 125){//down
}
if(theEvent.keyCode == 126){//up
speed+=1
print(speed)
}
}
override func viewDidLoad(){
super.viewDidLoad()
let scene = SCNScene(named: "art.scnassets/Plane.scn")!
let cameraNode = scene.rootNode.childNode(withName: "camera", recursively: true)!
let plane = scene.rootNode.childNode(withName: "plane", recursively: true)!
plane.runAction(SCNAction.repeatForever(SCNAction.moveBy(x: 0, y: CGFloat(height), z: CGFloat(speed), duration: 1)))
cameraNode.runAction(SCNAction.repeatForever(SCNAction.moveBy(x:0, y:CGFloat(height), z: CGFloat(speed), duration:1)))
let scnView = self.view as! SCNView
}
}
Once you have a created a SCNAction object with parameters that depend on the speed variable, any change to speed won't update the action.
This is because speed is a value type (Int) and there's no connection between the SCNAction instance and your view controller's speed instance variable. This is not an issue specific to SceneKit, any API that takes an Int as a parameter would behave the same way.
Related
Here is my previous question about in general apply force for a certain point of an AR object which had a perfect answer.
I have managed to apply force to a given point with a little bit of tinkering to have a perfect effect for me. Let me show also some code.
I get the AR object from Experience like:
if let skateAnchor = try? Experience.loadSkateboard(),
let skateEntity = skateAnchor.skateboard {
guard let entity = skateEntity as? HasPhysicsBody else { return }
skateAnchor.generateCollisionShapes(recursive: true)
entity.collision?.filter.mask = [.sceneUnderstanding]
skateboard = entity
}
Afterwards I set up the plane and the LiDAR scanner and add some gestures to it like:
let arViewTap = UITapGestureRecognizer(target: self,
action: #selector(tapped(sender:)))
arView.addGestureRecognizer(arViewTap)
let arViewLongPress = UILongPressGestureRecognizer(target: self,
action: #selector(longPressed(sender:)))
arView.addGestureRecognizer(arViewLongPress)
So far so good, on tap gesture I apply the logic from the previously linked answer and apply force impulse like:
if let sk8 = skateboard as? HasPhysics {
sk8.applyImpulse(direction, at: position, relativeTo: nil)
}
My issue comes with my "catching" logic, where I do want to use the long press, and apply downward force to my skateboard AR object like this:
#objc func longPressed(sender: UILongPressGestureRecognizer) {
if sender.state == .began || sender.state == .changed {
let location = sender.location(in:arView)
if arView.entity(at: location) is HasPhysics {
if let ray = arView.ray(through: location) {
let results = arView.scene.raycast(origin: ray.origin,
direction: ray.direction,
length: 100.0,
query: .nearest,
mask: .all,
relativeTo: nil)
if let _ = results.first,
let position = results.first?.position,
let normal = results.first?.normal {
// test different kind of forces
let direction = SIMD3<Float>(0, -20, 0)
if let sk8 = skateboard as? HasPhysics {
sk8.addForce(direction, at: position, relativeTo: nil)
}
}
}
}
}
}
Right now I know that I am ignoring the raycast results, but this is in pure development state, my issue is that when I apply positive/negative x/z the object responds well, it either slides back and forth or left or right, the positive y is also working by draging the board in the air, the only error prone force direction is the one I am striving to achieve is the downward facing negative y. The object just sits there with no effect at all.
Let also share how my object is defined inside the Reality Composer:
Ollie trick
In real life, if you shift your entire body's weight to the nose of the skateboard's deck (like doing the Ollie Maneuver), the skateboard's center of mass shifts from the middle towards the point where the force is being applied. In RealityKit, if you need to tear the rear (front) wheels of the skateboard off the floor, move the model's center of mass towards the slope.
The repositioning of the center of mass occurs in a local coordinate system.
import SwiftUI
import RealityKit
struct ContentView : View {
var body: some View {
ARViewContainer().ignoresSafeArea()
}
}
struct ARViewContainer: UIViewRepresentable {
func makeUIView(context: Context) -> ARView {
let arView = ARView(frame: .zero)
arView.debugOptions = .showPhysics // shape visualization
let scene = try! Experience.loadScene()
let name = "skateboard_01_base_stylized_lod0"
typealias ModelPack = ModelEntity & HasPhysicsBody & HasCollision
let model = scene.findEntity(named: name) as! ModelPack
model.physicsBody = .init()
model.generateCollisionShapes(recursive: true)
model.physicsBody?.massProperties.centerOfMass.position = [0, 0,-27]
arView.scene.anchors.append(scene)
return arView
}
func updateUIView(_ uiView: ARView, context: Context) { }
}
Physics shape
The second problem that you need to solve is to replace the model's box shape of the physical body (RealityKit and Reality Composer generate this type of shape by default). Its shape cannot be in the form of a monolithic box, it's quite obvious, because the box-shaped form does not allow the force to be applied appropriately. You need a shape similar to the outline of the model.
So, you can use the following code to create a custom shape:
(four spheres for wheels and box for deck)
let shapes: [ShapeResource] = [
.generateBox(size: [ 20, 4, 78])
.offsetBy(translation: [ 0.0, 11, 0.0]),
.generateSphere(radius: 3.1)
.offsetBy(translation: [ 7.5, 3, 21.4]),
.generateSphere(radius: 3.1)
.offsetBy(translation: [ 7.5, 3,-21.4]),
.generateSphere(radius: 3.1)
.offsetBy(translation: [-7.5, 3, 21.4]),
.generateSphere(radius: 3.1)
.offsetBy(translation: [-7.5, 3,-21.4])
]
// model.physicsBody = PhysicsBodyComponent(shapes: shapes, mass: 4.5)
model.collision = CollisionComponent(shapes: shapes)
P.S.
Reality Composer model's settings (I used Xcode 14.0 RC 1).
I'm working with ARKit / SceneKit and I'm trying to have an arrow point to an arbitrary position I set in the world, but I'm having a bit of trouble. In my sceneView I have a scene set up to load in my arrow.
override func viewDidLoad() {
super.viewDidLoad()
// Set the view's delegate
sceneView.delegate = self
guard let arrowScene = SCNScene(named: "art.scnassets/arrowScene.scn") else {
fatalError("Scene arrow.scn not found")
}
let worldAnchor = ARAnchor(name: "World Anchor", transform: simd_float4x4(1))
sceneView.session.add(anchor: worldAnchor)
sceneView.scene = (arrowScene)
}
I wish to then use SCNNode.look(at:) to point my arrow at the specified anchor, however, I am unsure how to get this to occur every frame. I know that I have access to special delegates provided by ARSCNView such as renderer(willUpdate node:), but I am unsure how to use these when the anchor is not changing positions whereas the arrow is.
Thanks for the help!
You could do so by using the updateAtTime delegate function, but I strongly recommend you to use a SCNConstraint.
let lookAtConstraint = SCNLookAtConstraint(target: myLookAtNode)
lookAtConstraint.isGimbalLockEnabled = true // useful for cameras, probably also for your arrow.
// in addition you can use a position constraint
let positionConstraint = SCNReplicatorConstraint(target: myLookAtNode)
positionConstraint.positionOffset = yourOffsetSCNVector3
positionConstraint.replicatesOrientation = false
positionConstraint.replicatesScale = false
positionConstraint.replicatesPosition = true
// then add the constraints to your arrow node
arrowNode.constraints = [lookAtConstraint, positionConstraint ]
This will automatically adjust your node for each rendered frame.
I am using sceneKit in my project, and would like to add a red sphere (as a marker)on the location that the user taps on a 3d model of a human body (see picture below). With the code I have currently, the sphere is added in the correct position - however, it not added on top of the human body, but rather extremely close to the camera (the z value is off). How can change the z value of the red sphere so that it is added on top of the human body rather than in front of the camera? Thank you so much :)
import UIKit
import QuartzCore
import SceneKit
class GameViewController: UIViewController {
var selectedNode: SCNNode!
var markerSphereNode: SCNNode!
var bodyNode: SCNNode!
#IBOutlet weak var sceneView: SCNView!
override func viewDidLoad() {
super.viewDidLoad()
let scene = SCNScene(named: "art.scnassets/femaleBodySceneKit Scene.scn")
markerSphereNode = scene?.rootNode.childNode(withName: "markerSphere", recursively: true)
bodyNode = scene?.rootNode.childNode(withName: "Body_M_GeoRndr", recursively: true)
sceneView.scene = scene
sceneView.allowsCameraControl = true
_ = sceneView.pointOfView
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
let touch = touches.first!
let touchPoint = touch.location(in: sceneView)
if sceneView.hitTest(touch.location(in: sceneView), options: nil).first != nil {
markerSphereNode.position = sceneView.unprojectPoint(
SCNVector3(x: Float(touchPoint.x),
y: Float(touchPoint.y),
z: 0.56182814))
}
}
}
how the red sphere appears when you tap on a location in the body
how far it is from the body when you rotate the camera (it is in the background if you look closely
how the red dot SHOULD appear
SCNHitTestResult provides you with localCoordinates and worldCoordinates already. There's a need to use the unprojectPoint method.
I am not able to figure out how to make the "ball" entity a physics entity/body and apply a force to it.
// I'm using UIKit for the user interface and RealityKit +
// the models made in Reality Composer for the Augmented reality and Code
import RealityKit
import ARKit
class ViewController: UIViewController {
var ball: (Entity & HasPhysics)? {
try? Entity.load(named: "golfball") as? Entity & HasPhysics
}
#IBOutlet var arView: ARView!
// referencing the play now button on the home screen
#IBAction func playNow(_ sender: Any) { }
// referencing the slider in the AR View - this slider will be used to
// control the power of the swing. The slider values range from 10% to
// 100% of swing power with a default value of 55%. The user will have
// to gain experience in the game to know how much power to use.
#IBAction func slider(_ sender: Any) { }
//The following code will fire when the view loads
override func viewDidLoad() {
super.viewDidLoad()
// defining the Anchor - it looks for a flat surface .3 by .3
// meters so about a foot by a foot - on this surface, it anchors
// the golf course and ball when you tap
let anchor = AnchorEntity(plane: .horizontal, minimumBounds: [0.3, 0.3])
// placing the anchor in the scene
arView.scene.addAnchor(anchor)
// defining my golf course entity - using modelentity so it
// participates in the physics of the scene
let entity = try? ModelEntity.load(named: "golfarnew")
// defining the ball entity - again using modelentity so it
// participates in the physics of the scene
let ball = try? ModelEntity.load(named: "golfball")
// loading my golf course entity
anchor.addChild(entity!)
// loading the golf ball
anchor.addChild(ball!)
// applying a force to the ball at the balls position and the
// force is relative to the ball
ball.physicsBody(SIMD3(1.0, 1.0, 1.0), at: ball.position, relativeTo: ball)
// sounds, add physics body to ball, iPad for shot direction,
// connect slider to impulse force
}
}
Use the following code to find out how to implement a RealityKit's physics.
Pay particular attention: Participates in Physics is ON in Reality Composer.
import ARKit
import RealityKit
class ViewController: UIViewController {
#IBOutlet var arView: ARView!
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
let boxScene = try! Experience.loadBox()
let secondBoxAnchor = try! Experience.loadBox()
let boxEntity = boxScene.steelBox as! (Entity & HasPhysics)
let kinematics: PhysicsBodyComponent = .init(massProperties: .default,
material: nil,
mode: .kinematic)
let motion: PhysicsMotionComponent = .init(linearVelocity: [0.1 ,0, 0],
angularVelocity: [3, 3, 3])
boxEntity.components.set(kinematics)
boxEntity.components.set(motion)
let anchor = AnchorEntity()
anchor.addChild(boxEntity)
arView.scene.addAnchor(anchor)
arView.scene.addAnchor(secondBoxAnchor)
print(boxEntity.isActive) // Entity must be active!
}
}
Also, look at THIS POST to find out how to implement RealityKit's physics with a custom class.
I would like to create two 3D objects on the AR scene according to the value of the string provided. The default value of the string is "1" and after that, I will jump to another ViewController and change the string value to "2" and then back to the ARViewController.
I would like to ask how can I keep the existing node and world origin of the AR scene remain unchanged when I move to another ViewController and then come back to ARViewController? It seems that every time when I come back to the AR scene, it will do the world tracking again and remove my existing node and world origin.I can only display the latest 3D object by string value "2". The 3D object created by string "1" is being removed.
Here is the code for the AR ViewController:
class ARViewController: UIViewController {
public var object = Connector()
#IBOutlet weak var ARScene: ARSCNView!
public let configuration = ARWorldTrackingConfiguration()
override func viewDidLoad() {
super.viewDidLoad()
self.ARScene.session.run(configuration)
}
override func viewDidAppear(_ animated: Bool) {
if object.stringbeingpassed == "1"{
self.addNode(newposition: SCNVector3(0,0,0))
}else{
self.addNode(newposition: SCNVector3(0.1,0.1,0.1))
}
}
func addNode(newposition:SCNVector3){
let ball = SCNNode()
ball.geometry = SCNSphere(radius: 0.02)
ball.position = newposition
self.ARScene.scene.rootNode.addChildNode(ball)
let action = SCNAction.rotateBy(x: 0, y:CGFloat(360.degreesToRadians), z: 0, duration: 4)
let forever = SCNAction.repeatForever(action)
ball.runAction(forever)
}