How to make new instances of a SCNNode with different texture - ios

Question

I load meshes from COLLADA files into SceneKit. Let's say I have a cube with a material that has a certain texture. Then in code, I want to make new copies of this SCNNode - I have used clone so far - and then I need to set a new texture. This is where it gets problematic because if I get the named material of one of the cloned cubes and update its texture (thematerialofmycube.diffuse.contents = #"somefile.png"), will set the same texture to all instances of the cube. clone obviously does not deep copy things like geometry, materials and textures. So what I have tried is making a copy of the geometry itself, and also tried making a new material, setting a new texture to the new material, and adding that material to the materials array of the new geometry, while also removing the old material. There seems to be no straightforward way of doing it this way (the materials are named, but exist in an array so several materials could theoretically have the same name - which leads to some bulky adding/removing of objects from the array), and when I do it, the new textures show up, but they show up upside down, and also the order of materials seem incorrect as I get "backside" textures in place of frontside textures and vice versa. I hope I don't have to draw all this stuff in my 3d editor, there must be a good way of making new instances with arbitrarily specified textures in code.
What I'm specifically doing is I drew a trump card in my 3d editor, and exported it to COLLADA. Now I have 52 pngs of trump card faces - I need to replace the faces of new instances of trump cards obviously.

Answer 1

It seems that the order of the materials in that array is (very) important. If I insert the new material with the updated texture in the same array index as the one I remove, essentially doing a replace, then textures show up on the correct face and aren't upside down - ie they show up in the same way as with the source SCNNode. I have yet to run this for a longer time to see if this works consistently.

Answer 2

[SCNNode clone] do this way for efficiency reasons.Try this code (If you want make a SCNNode Category:
//********************************************************
//<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
// SCNNode duplicate
//********************************************************
//<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
- (SCNNode *)duplicateNode:(SCNNode *)node
{
SCNNode *newNode = [node clone];
newNode.geometry = [node.geometry copy];
newNode.geometry.firstMaterial = [node.geometry.firstMaterial copy];
return newNode;
}

Answer 3

Swift answer:
fileprivate func deepCopyNode(node: SCNNode) -> SCNNode {
let clone = node.clone()
clone.geometry = node.geometry?.copy() as? SCNGeometry
if let g = node.geometry {
clone.geometry?.materials = g.materials.map{ $0.copy() as! SCNMaterial }
}
return clone
}

Answer 4

Been a long time since this was asked. But thought I'd offer a helper function I have:
func deepCopyNode(_ node: SCNNode) -> SCNNode {
// internal function for recurrsive calls
func deepCopyInternals(_ node: SCNNode) {
node.geometry = node.geometry?.copy() as? SCNGeometry
if let g = node.geometry {
node.geometry?.materials = g.materials.map { $0.copy() as! SCNMaterial }
}
for child in node.childNodes {
deepCopyInternals(child)
}
}
// CLONE main node (and all kids)
// issue here is that both geometry and materials are linked
// still. In our deepCopyNode we want new copies of everything
let clone = node.clone()
// we use this internal function to update both
// geometry and materials, as well as process all children
// this is the *deep* part of "deepCopy"
deepCopyInternals(clone)
return clone
}