I want to be able to create a custom camera node in SceneKit and view my scene from it (instead of the default camera).
However, I've been encountering a very strange issue with SceneKit:
If I use SCNCamera, nothing shows up in my scene.
If I don't use SCNCamera, the objects in my scene render
correctly.
This is the code I am using (very simple code; from a tutorial):
import UIKit
import SceneKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let sceneView = SCNView()
sceneView.frame = self.view.frame
self.view.addSubview(sceneView)
let scene = SCNScene()
sceneView.autoenablesDefaultLighting = true
sceneView.allowsCameraControl = true
let cameraNode = SCNNode()
// If the below line of code is commented out (so no SCNCamera is added), everything shows up
cameraNode.camera = SCNCamera()
scene.rootNode.addChildNode(cameraNode)
let sphere = SCNSphere(radius: 5)
sphere.firstMaterial?.diffuse.contents = UIColor.red
let sphereNode = SCNNode(geometry: sphere)
cameraNode.addChildNode(sphereNode)
sceneView.backgroundColor = UIColor.green
sceneView.scene = scene
}
}
This seems pretty straightforward, yet I can't find any reason why this is happening on SO, etc.
Strangely, I also observe that if I try to access the camera node via sceneView.pointOfView, I get nil, even though sceneView.allowsCameraControl is set to true
Any help is appreciated!
The sphere is a child node of the camera, without any offset (its position is (0, 0, 0)) and so the camera is inside the sphere. And if the sphere's material isn't doubleSided then you won't see anything.
Related
I am creating an iOS ARKit app where I wanted to place a large object in Augmented Reality.
When I am trying to place the object at a particular position it always appears to be moving with the change in camera position and I am not able to view the object from all angles by changing the camera position.
But if I reduce it's scale value to 0.001 (Reducing the size of the object), I am able to view the object from all angles and the position of the placed object also does not change to that extent.
Bounding Box of the Object:-
Width = 3.66
Height = 1.83
Depth = 2.438
Model/Object Url:-
https://drive.google.com/open?id=1uDDlrTIu5iSRJ0cgp70WFo7Dz0hCUz9D
Source Code:-
import UIKit
import ARKit
import SceneKit
class ViewController: UIViewController {
#IBOutlet weak var sceneView: ARSCNView!
private let configuration = ARWorldTrackingConfiguration()
private var node: SCNNode!
//MARK: - Life cycle
override func viewDidLoad() {
super.viewDidLoad()
self.sceneView.showsStatistics = false
self.sceneView.debugOptions = [ARSCNDebugOptions.showFeaturePoints]
self.sceneView.automaticallyUpdatesLighting = false
self.sceneView.delegate = self
self.addTapGesture()
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
configuration.planeDetection = .horizontal
self.sceneView.session.run(configuration)
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
self.sceneView.session.pause()
}
//MARK: - Methods
func addObject(hitTestResult: ARHitTestResult) {
let scene = SCNScene(named: "art.scnassets/Cube.obj")!
let modelNode = scene.rootNode.childNodes.first
modelNode?.position = SCNVector3(hitTestResult.worldTransform.columns.3.x,
hitTestResult.worldTransform.columns.3.y,
hitTestResult.worldTransform.columns.3.z)
let scale = 1
modelNode?.scale = SCNVector3(scale, scale, scale)
self.node = modelNode
self.sceneView.scene.rootNode.addChildNode(modelNode!)
let lightNode = SCNNode()
lightNode.light = SCNLight()
lightNode.light?.type = .omni
lightNode.position = SCNVector3(x: 0, y: 10, z: 20)
self.sceneView.scene.rootNode.addChildNode(lightNode)
let ambientLightNode = SCNNode()
ambientLightNode.light = SCNLight()
ambientLightNode.light?.type = .ambient
ambientLightNode.light?.color = UIColor.darkGray
self.sceneView.scene.rootNode.addChildNode(ambientLightNode)
}
private func addTapGesture() {
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(didTap(_:)))
self.sceneView.addGestureRecognizer(tapGesture)
}
#objc func didTap(_ gesture: UIPanGestureRecognizer) {
let tapLocation = gesture.location(in: self.sceneView)
let results = self.sceneView.hitTest(tapLocation, types: .featurePoint)
guard let result = results.first else {
return
}
let translation = result.worldTransform.translation
guard let node = self.node else {
self.addObject(hitTestResult: result)
return
}
node.position = SCNVector3Make(translation.x, translation.y, translation.z)
self.sceneView.scene.rootNode.addChildNode(self.node)
}
}
extension float4x4 {
var translation: SIMD3<Float> {
let translation = self.columns.3
return SIMD3<Float>(translation.x, translation.y, translation.z)
}
}
GIF of the Problem:-
Video URL of the Problem:-
https://drive.google.com/open?id=1E4euZ0ArEtj2Ffto1pAOfVZocV08EYKN
Approaches Tried:-
Tried to place the object at the origin
modelNode?.position = SCNVector3(0, 0, 0)
Tried to place the object at some distance away from the device camera
modelNode?.position = SCNVector3(0, 0, -800)
Tried with the different combinations of worldTransform/localTransform columns
modelNode?.position = SCNVector3(hitTestResult.worldTransform.columns.3.x, hitTestResult.worldTransform.columns.3.y, hitTestResult.worldTransform.columns.3.z)
modelNode?.position = SCNVector3(hitTestResult.worldTransform.columns.2.x, hitTestResult.worldTransform.columns.2.y, hitTestResult.worldTransform.columns.2.z)
modelNode?.position = SCNVector3(hitTestResult.worldTransform.columns.1.x, hitTestResult.worldTransform.columns.1.y, hitTestResult.worldTransform.columns.1.z)
modelNode?.position = SCNVector3(hitTestResult.worldTransform.columns.1.x, hitTestResult.worldTransform.columns.2.y, hitTestResult.worldTransform.columns.3.z)
modelNode?.position = SCNVector3(hitTestResult.localTransform.columns.3.x, hitTestResult.localTransform.columns.3.y, hitTestResult.localTransform.columns.3.z)
But still of no luck. It still appears to be moving with the device camera and not stuck to a position where it has been placed.
Expected Result:-
Object should be of actual size (Scale should be of 1.0). Their should be no reduction in the scale value.
Once placed at a particular position it should not move with the movement of the device camera.
Object can be seen from all angles with the movement of the device camera without any change in object position.
Unlike stated in the accepted answer, the issue is probably not about the tracking quality or a bug in the model. It looks like the model is not correctly placed on top of the ground, probably due to a mispositioned pivot point, and some part of the model stays under ground. So when you move the camera, since the part under ground is not occluded by the floor, it looks like it is shifting. Have a look at this picture:
The pivot points of the models provided by Apple are positioned correctly so that when it is placed on top of a plane on the ground, its parts stay above ground.
If you correctly position the pivot point of the model, it should work correctly, independent of the model type.
I found out the root cause of the issue. The issue was related to the Model which I was using for AR. When, I replaced the model with the one provided in this link:- https://developer.apple.com/augmented-reality/quick-look/. I was not facing any issues. So, if anyone face such type of issues in future I would recommend to use any of the model provided by Apple to check if the issue persists with it or not.
I experienced the same issue.
Whenever I try to change anything in our Model of .usdz type (which is actually an Encrypted and compressed type) we cannot edit or change anything in it. If I edit or change a little position then it behaves same way as highlighted in the question.
To handle this issue, I just moved the old model .usdz to trash and and copied the original file (again) to XCode and then it worked.
I can't find a good explanation of what a SCNCamera is and it's purpose. This is Apple's definition:
A set of camera attributes that can be attached to a node to provide a
point of view for displaying the scene.
This definition isn't clear because I set up the scene and added a SCNNode without attaching a SCNCamera to it. The point of view from the device's camera shows the SCNNode at the location I positioned it at with no problem and the scene is displayed fine.
What is the difference between the device's camera and a SCNCamera?
What is the benefit of attaching a SCNCamera to a SCNNode vs not using one?
If I have multiple SCNNodes (all detached no hierarchy amongst each other) does each node need it's own SCNCamera?
If I have multiple SCNNodes in a hierarchy (parent node with child nodes) does each node need it's own SCNCamera or does just the parent node?
lazy var sceneView: ARSCNView = {
let sceneView = ARSCNView()
sceneView.translatesAutoresizingMaskIntoConstraints = false
sceneView.delegate = self
return sceneView
}()
let configuration = ARWorldTrackingConfiguration()
override func viewDidLoad() {
super.viewDidLoad()
// pin sceneView to the view
let material = SCNMaterial()
material.diffuse.contents = UIImage(named: "earth")
let plane = SCNPlane(width: 0.33, height: 0.33)
plane.materials = [material]
plane.firstMaterial?.isDoubleSided = true
let myNode = SCNNode(geometry: plane)
myNode.name = "earth"
myNode.position = SCNVector3(0.0, 0.6, -0.9)
sceneView.scene.rootNode.addChildNode(myNode)
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
sceneView.session.run(configuration, options: [])
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillAppear(animated)
sceneView.session.pause()
sceneView.session.run(configuration, options: [.resetTracking, .removeExistingAnchors])
}
In SceneKit, the SCNCamera represents the point of view from which the user sees a scene. Ray Wenderlich provides a good explanation:
Think back to the analogy of the movie set from Chapter 1: to shoot a
scene, you’d position a camera looking at the scene and the resulting
image of that scene would be from the camera’s perspective.
Scene Kit
works in a similar fashion; the position of the node that contains the
camera determines the point of view from which you view the scene.
You do not need to have a SCNCamera for each node. You should only need to have one camera for each angle that you want to show, or even just one. You can move one camera throughout the scene using its parent's position property.
It looks like you're working with ARKit, which behaves a little differently. When using an ARSCNView, as opposed to a non-AR SCNView, you get the following behvior:
The view automatically renders the live video feed from the device camera as the scene background.
The world coordinate system of the view's SceneKit scene directly responds to the AR world coordinate system established by the session
configuration.
The view automatically moves its SceneKit camera to match the real-world movement of the device.
You do not need to worry as much about the scene's camera in this case, as it is automatically being controlled by the system so that it matches the device's movement for AR.
For more detail, see Apple's documentation on SCNCamera: SCNCamera - SceneKit
I got the answer to my question from within this answer. Basically in ARKit using ARSCNView the camera comes from sceneView.pointOfView but in SceneKit you need to create a camera to get the camera pov (code below).
Getting the camera node
To get the camera node, it depends if you're using SCNKit, ARKit, or other framework. Below are examples for ARKit and SceneKit.
With ARKit, you have ARSCNView to render the 3D objects of an SCNScene overlapping the camera content. You can get the camera node from ARSCNView's pointOfView property:
let cameraNode = sceneView.pointOfView
For SceneKit, you have an SCNView that renders the 3D objects of an SCNScene. You can create camera nodes and position them wherever you want, so you'd do something like:
let scnScene = SCNScene()
// (Configure scnScene here if necessary)
scnView.scene = scnScene
let cameraNode = SCNNode()
cameraNode.camera = SCNCamera()
cameraNode.position = SCNVector3(0, 5, 10) // For example
scnScene.rootNode.addChildNode(cameraNode)
Once a camera node has been setup, you can access the current camera in the same way as ARKit:
let cameraNode = scnView.pointOfView
This question already has an answer here:
Applying simple Physics to a .scn object in SceneKit XCODE SWIFT
(1 answer)
Closed 6 years ago.
Hey I have a scene kit scene and my goal is just to get the guy/character on the scene to fall do to gravity and then hit the floor. Thats it. the "Guy" is simple a node .scn node. and the ground is a also a .scn scene as shown in the code below. Ive gotten as far as the skills I have to try and add simple physics to the scene. I know how to add physics perfectly in SPRITEKIT but the .scn nodes don't let me attach the same variable that would use give the character physics. There are no errors in this code But the character is not affect by gravity when ran Thanks
Code:
// Collision bit masks
let BitmaskCollision = 1 << 2
let BitmaskCollectable = 1 << 3
let BitmaskEnemy = 1 << 4
let BitmaskFriend = 1 << 5
let BitmaskOutofBounds = 1 << 6
class GameViewController: UIViewController, ADBannerViewDelegate, SKPhysicsContactDelegate, SKSceneDelegate, SCNSceneRendererDelegate, SCNPhysicsContactDelegate{
// The character
let character = Character()
// The Playing Fields
let FieldScene = SCNScene(named: "art.scnassets/TesingCampusField.dae")!
override func viewDidLoad() {
super.viewDidLoad()
let scnView = self.view as! SCNView
scnView.scene = FieldScene
scnView.playing = true
scnView.delegate = self
scnView.scene!.physicsWorld.contactDelegate = self
//-----Adding Gravity----------------------------------------------
scnView.scene!.physicsWorld.gravity = SCNVector3(x: 0, y: 0, z: -9.8)
//------Add-the-Character-to-Scene--------------------
scnView.scene!.rootNode.addChildNode(character.node)
}
End Of code for this Controller
The Character is simply being set up from a file called "Character"
class Character {
let node = SCNNode()
init() {
let GuyScene = SCNScene(named: "art.scnassets/Guy.scn")
let characterTopLevelNode: SCNNode = GuyScene!.rootNode.childNodeWithName("Guy", recursively: true)!
node.addChildNode(characterTopLevelNode)
characterTopLevelNode.physicsBody?.contactTestBitMask = BitmaskEnemy
characterTopLevelNode.physicsBody?.collisionBitMask = BitmaskCollision
characterTopLevelNode.physicsBody?.categoryBitMask = BitmaskCollectable
characterTopLevelNode.physicsBody?.affectedByGravity = true
characterTopLevelNode.physicsBody?.friction = 0
characterTopLevelNode.physicsBody?.restitution = 0
characterTopLevelNode.physicsBody?.angularDamping = 0
// Below is the Creation of the Physics body of the character
let (min, max) = node.boundingBox
let collisionCapsuleRadius = CGFloat(max.x - min.x) * 0.4
let collisionCapsuleHeight = CGFloat(max.y - min.y)
let characterCollisionNode = SCNNode()
characterCollisionNode.name = "collider"
// position light above the floor so you dont hit it and cause a contact
characterCollisionNode.position = SCNVector3(0.0, collisionCapsuleHeight * 0.51, 0.0)
characterCollisionNode.physicsBody = SCNPhysicsBody(type: .Dynamic, shape:SCNPhysicsShape(geometry: SCNCapsule(capRadius: collisionCapsuleRadius, height: collisionCapsuleHeight), options:nil))
// Adding the Pysics body of the character called "characterCollisionNode" to the actually character
node.addChildNode(characterCollisionNode)
}
}
This seems to be an earlier version of this question Applying simple Physics to a .scn object in SceneKit XCODE SWIFT
And the answer is probably similar, you don't appear to be adding the node as a child of the scene.
Hey I make a jumping man animation in blender and I imported it in scene kit.
It works fine but there is a problem as I want to make the man not jump until user touch but this character start jumping automatically when I run my code.
How can I control animation not jump automatically?
I have this code:
class GameViewController: UIViewController {
var messiArmtr = SCNNode()
var KickAnimation = CAAnimation()
var BoxingAnimation = CAAnimation()
override func viewDidLoad() {
super.viewDidLoad()
let scene = SCNScene(named: "art.scnassets/messi.dae")!
let cameraNode = SCNNode()
cameraNode.camera = SCNCamera()
scene.rootNode.addChildNode(cameraNode)
let messiamtr = scene.rootNode.childNodeWithName("amtr", recursively: true)!
KickAnimation = CAAnimation.animationWithSceneNamed("art.scnassets/move.dae")!
messiamtr.addAnimation(KickAnimation, forKey: "amtr")
it's not really automatic, you asked it to be played when you added it:
messiamtr.addAnimation(KickAnimation, forKey: "amtr")
I added one line of code (where it says //LINE CHANGED) to change the material to a blue color. However, when I load the game, the default ship stays as the normal texture. Any ideas as to why this is happening? I can change the material just fine on a cube I make but for some reason the ships material is not changing.
override func viewDidLoad() {
super.viewDidLoad()
// create a new scene
let scene = SCNScene(named: "art.scnassets/ship.dae")!
// 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: 0, y: 0, z: 15)
// create and add a light to the scene
let lightNode = SCNNode()
lightNode.light = SCNLight()
lightNode.light!.type = SCNLightTypeOmni
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 = SCNLightTypeAmbient
ambientLightNode.light!.color = UIColor.darkGrayColor()
scene.rootNode.addChildNode(ambientLightNode)
// retrieve the ship node
let ship = scene.rootNode.childNodeWithName("ship", recursively: true)!
//LINE CHANGED
ship.geometry?.firstMaterial?.diffuse.contents = UIColor.blueColor()
//LINE CHANGED
// animate the 3d object\
ship.runAction(SCNAction.repeatActionForever(SCNAction.rotateByX(0, y: 2, z: 0, duration: 1)))
// 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.blackColor()
// add a tap gesture recognizer
let tapGesture = UITapGestureRecognizer(target: self, action: "handleTap:")
let gestureRecognizers = NSMutableArray()
gestureRecognizers.addObject(tapGesture)
if let existingGestureRecognizers = scnView.gestureRecognizers {
gestureRecognizers.addObjectsFromArray(existingGestureRecognizers)
}
scnView.gestureRecognizers = gestureRecognizers
}
ship.geometry is nil. So the rest of the line will have no effect.
If you inspect the file "ship.dae" in xcode you will see that the node named "ship" has no geometry attached but it has a child node named "shipMesh" that owns the geometry.
Toyos already covered the answer pretty well, but I wanted to add some advice that's too long for a comment...
There's an inherent danger to optional chaining in Swift (or messaging things that can be nil in ObjC, for that matter) — if it fails, it'll do so silently. You might say that's less bad than a crash, but it's harder to debug.
Instead of writing a longChain?.of?.optionalCalls(), consider using optional binding (if let) for parts of it so you can see where the chain is breaking due to a nil value. It's more code, but it lets you check each step of the chain and handle failures in a way that makes the most sense to your app. This can even be a debugging strategy — if you have a line of optional-chained calls that seems to be doing nothing, replace it with an equivalent nesting of if let statements until you find the problem. (Then go back to optional chaining once you've fixed it, if you like.)
Lots of people harsh on implicitly unwrapped optionals, but there are times and places where they can be useful. I'd say this is one of them — the chain of optionals you need to get through is something you can assure at app build time (just not at source compile time), because it's the configuration of a DAE shipped in your app. (This is basically the same rationale as that behind IBOutlets typically being IUOs.) Writing ship.geometry!.firstMaterial!.contents would alert you to the mismatch between what your DAE has and what you think it has, because you'd crash dereferencing geometry.