How do you load a .dae file into an SCNNode in iOS SceneKit?

Question

I am having trouble understanding how geometry from .dae files should be loaded into an iOS SceneKit scene graph.

I know that you can load .dae files directly into an SCNScene:

// create a new scene
let scene = SCNScene("test.scnassets/test.dae")

I also know that you can create an empty SCNScene and add built-in 3D objects into it as child nodes:

let scene = SCNScene()
var sphereNode = SCNNode()
sphereNode.geometry = SCNSphere(radius: 1.0)
scene.rootNode.addChildNode(sphereNode)

In the second case, can you load a .dae file into SCNNode instead of using built in objects? Or is it expected that all .dae files need to be loaded into the SCNScene first?

If the latter is true, how then do you place the SCNNode objects into the right place in the scene graph hierarchy under SCNScene?

EDIT #1:

This is working for me now, which is modified version of what @FlippinFun suggested.

let url = NSBundle.mainBundle().URLForResource("test.scnassets/test", withExtension: "dae")
let source = SCNSceneSource(URL: url, options: nil)
let block = source.entryWithIdentifier("ID10", withClass: SCNGeometry.self) as SCNGeometry
scene.rootNode.addChildNode(SCNNode(geometry: block))

But perhaps there's a better way? The above involves manually loading each identifier from the .dae tree. In my file, there's a node "SketchUp" with child identifiers "ID2" and "ID10". This method will not let you load the root "SketchUp". (I get a runtime error.)

Sylviasylviculture

I already post this. Here is a link. #25032274 – Martyr

Thanks. So your suggestion is to use SCNSceneSource. Unfortunately that's crashing for me at the moment. – Sylviasylviculture

There seems to be a bug in your code that retrives the geometry. The class should be SCNGeometry rather than SCNNode. Eg: let block = source.entryWithIdentifier("ID10", withClass: SCNGeometry.self) as SCNGeometry. With this fix, it's working for me. – Sylviasylviculture

Yes there is a bug. I will make an edit. Thanks! – Martyr

Re this 10 yr old question. The full answer these days (2023) is https://mcmap.net/q/245407/-how-to-get-a-ordinary-mixamo-character-animation-working-in-scenekit – Bucephalus

Answer 1

The usual pattern is to load your scene and retrieve the node you are interested in with its name using

[scene.rootNode childNodeWithName:aName recursively:YES];

Then you can reparent this node to your main scene.

Scad

But in that case, the node is already a direct child of the root node, correct? So if I need to it to be under some other node in the scene graph, I will need to reposition it, with this approach. That's why I was asking about loading the SCNNode geometry independent of the SCNScene. – Sylviasylviculture

In any case, this is a useful approach. Thanks. – Sylviasylviculture

you would typically create a new scene with your "other" dae file, retrieve the node you are interested in, and reparent it in your main scene – Parasiticide

How do you typically reparent a node? – Sylviasylviculture

you can take a look at the -[SCNNode asc_addChildNodeNamed:fromSceneNamed:withScale:] extension method in the WWDC 2014 sample code. Build the scene, get the node with -childNodeWithName:recursively: and then simply -addChildNode: to a node in your main scene. – Parasiticide

Why didn't add scene1.rootNode to scene2 ? My .scn file ONLY have animations on rootNode, how to deal with this. – Mulry

Answer 2

I had a similar problem where I had one .dae file and I wanted to load multiple nodes from that file into a node. This worked for me:

var node = SCNNode()
let scene = SCNScene(named: "helloScene.dae")
var nodeArray = scene.rootNode.childNodes

for childNode in nodeArray {
  node.addChildNode(childNode as SCNNode)
}

First, I set a node that will hold it all together so it looks like it does in the original file. Next we import the .dae file we want and copy all the nodes inside of it. Lastly, for each node in the array I added it to the node.

Indecorous

I replaced var nodeArray = scene.rootNode.childNodes with var nodeArray = scene!.rootNode.childNodes – Pigeon

Answer 3

Thanks for your help!

Here is a simple collada2Node class.

//collada2SCNNode
class func collada2SCNNode(filepath:String) -> SCNNode {
    var node = SCNNode()
    let scene = SCNScene(named: filepath)
    var nodeArray = scene!.rootNode.childNodes

    for childNode in nodeArray {
        node.addChildNode(childNode as SCNNode)
    }
    return node
}

Collettecolletti

Answer 4

func nodeWithFile(path: String) -> SCNNode {

    if let scene = SCNScene(named: path) {

        let node = scene.rootNode.childNodes[0] as SCNNode
        return node

    } else {
        println("Invalid path supplied")
        return SCNNode()
    }

}

Unconcerned

Answer 5

The following answers didn't work for me.

Here is what worked for me in Xcode 7.0 beta 5 , iOS 9.0 beta / Swift 2.0:

3D model type: Collada 3D model name: "model.dae"

1. Load the scene:

   let lampScene = SCNScene(named: "art.scnassets/model.dae")
   

2. Access the child SCNode which is in the SCNScene:

   let lampRootNode = lampScene?.rootNode.childNodes[0]
   

3. Add the lamp node from the loaded scene into the current loaded and viewed scene:

   self.scene.rootNode.addChildNode(lampRootNode!)
   

NOTE: The self.scene exists due to:

private var scene:SCNScene!

Prior of adding the object to the scene I have made some scene setup according to the scene kit example. If you need the code mention it in the comments.

Hope it helps.

Maitilde

Why didn't you use a SCNReferenceNode? Is there an advantage to this approach? – Venom

Answer 6

The only practical way we have found to so this: 2023.

(1) Very simply open the YourFileName.dae file, using a normal real text editor such as VSCode.

Notice that the file contains things like materials, effects, etc.

Simply scroll to the library_geometries and you'll immediately see the id,

In this case "geometry316".

(Note that almost always the library_geometries is simply the final long line of the file, easy to find.)

Very simply, the id (example, "geometry316") is NOT SHOWN IN XCODE, it's just an Xcode bug they will likely fix soon.

(2) Then to get and show the node it's just:

var kingDragon: SCNNode!
...


let p = Bundle.main.url(forResource: "Badass Dragon", withExtension: "dae")!
let source = SCNSceneSource(url: p, options: nil)!
let g = source.entryWithIdentifier("geometry316",
              withClass: SCNGeometry.self)! as SCNGeometry
kingDragon = SCNNode(geometry: g)
castleWall.addChildNode(kingDragon)

That's it.

Note!

If you further wish to load and use character animations, the total solution is outlined here: https://mcmap.net/q/245407/-how-to-get-a-ordinary-mixamo-character-animation-working-in-scenekit

Bucephalus

Answer 7

guard let shipScene = SCNScene(named: "ship.dae") else { return }
let shipNode = SCNNode()
let shipSceneChildNodes = shipScene.rootNode.childNodes
for childNode in shipSceneChildNodes {
    shipNode.addChildNode(childNode)
}

Matheny