Cannot change color of SCNCone - Scenekit - swift

Question

I have an 'attach node' that has 2 child nodes that are Blender models. I have added a third node to this attach node that is a SCNCone. For some reason, I can't change the color of the cone node, only the transparency. I can't seem to see anything wrong with the code, but during runtime the cone is always a black color no matter what color I set it to.
let coneGeo = SCNCone(topRadius: 0.1, bottomRadius: 0.7, height: 4)
let coneMaterial = SCNMaterial()
coneMaterial.diffuse.contents = UIColor(red: 255.0/255.0, green: 108.0/255.0, blue: 91.0/255.0, alpha: 0.2)
coneGeo.materials = [coneMaterial]
let coneNode = SCNNode(geometry: coneGeo)
coneNode.position = SCNVector3(0, -1.5, 0)
coneNode.name = "coneNode"
AttachNode.addChildNode(coneNode)

Answer 1

Replace coneMaterial.diffuse.contents = UIColor(red: 255.0/255.0, green: 108.0/255.0, blue: 91.0/255.0, alpha: 0.2) with coneGeo.geometry?.firstMaterial?.diffuse.contents.diffuse.contents = UIColor(red: 255.0/255.0, green: 108.0/255.0, blue: 91.0/255.0, alpha: 0.2). Instead of changing the cone's material color without geometry, you have to access it's material color through it's geometry parameter.

Answer 2

coneGeo.materials = [coneMaterial]
This will also work. I tested your code by adding the cone node to an empty scene.
I just get a black screen.
But if I change the alpha value to say 0.5, this is what I get.
The code.
override func viewDidLoad()
{
super.viewDidLoad()
// create a new scene
let scene = SCNScene()
let coneGeo = SCNCone(topRadius: 0.1, bottomRadius: 0.7, height: 4)
let coneMaterial = SCNMaterial()
coneMaterial.diffuse.contents = UIColor(red: 255.0 / 255.0,
green: 108.0 / 255.0,
blue: 91.0 / 255.0, alpha: 0.5)
coneGeo.materials = [coneMaterial]
let coneNode = SCNNode(geometry
: coneGeo)
coneNode.position = SCNVector3(0, -1.5, 0)
coneNode.name = "coneNode"
scene.rootNode.addChildNode(coneNode)
// 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
}
So I would say, check your alpha value in UIColor(red: 255.0/255.0, green: 108.0/255.0, blue: 91.0/255.0, alpha: 0.2)