Scenekit shape between 4 points - swift

Question

Given that the route I was taking in a previous question:
ARKit - place a SCNPlane between 2 vector points on a plane in Swift 3
...seems to be flawed, I'm looking at other options. I can draw a line between 2 nodes, I can then create nodes above those, effectively in a square but even if I draw lines between them all, I can't make that into a shape. Is it possible in Scenekit to draw a shape (square) where each of the 4 corners joins to a node.
I can create a plane, position it on a node, transform the pivot and then rotate but it doesn't always work but SCNGeometry lines do.
Thanks

Answer 1

So the answer, at least my solution is to use SCNGeometry triangles. I wanted a square (rather than a cube) to act as a wall in Augmented Reality so I simply built 2 triangles using the 4 nodes that mapped the 4 corners of a wall.
The class to build the triangle:
extension SCNGeometry {
class func triangleFrom(vector1: SCNVector3, vector2: SCNVector3, vector3: SCNVector3) -> SCNGeometry {
let indices: [Int32] = [0, 1, 2]
let source = SCNGeometrySource(vertices: [vector1, vector2, vector3])
let element = SCNGeometryElement(indices: indices, primitiveType: .triangles)
return SCNGeometry(sources: [source], elements: [element])
}
}
The points for the 2 triangles are [p1, p2, p4] and [p1, p3, p4] called using the following:
let thirdPoint = firstPoint.clone()
thirdPoint.position = SCNVector3Make(thirdPoint.position.x,
thirdPoint.position.y + Float(1.5), thirdPoint.position.z)
sceneView.scene.rootNode.addChildNode(thirdPoint)
let fourthPoint = secondPoint.clone()
fourthPoint.position = SCNVector3Make(fourthPoint.position.x,
fourthPoint.position.y + Float(1.5), fourthPoint.position.z)
sceneView.scene.rootNode.addChildNode(fourthPoint)
let triangle = SCNGeometry.triangleFrom(vector1: firstPoint.position, vector2: secondPoint.position, vector3: fourthPoint.position)
let triangleNode = SCNNode(geometry: triangle)
triangleNode.geometry?.firstMaterial?.diffuse.contents = UIColor.blue
triangleNode.geometry?.firstMaterial?.isDoubleSided = true
sceneView.scene.rootNode.addChildNode(triangleNode)
let triangle2 = SCNGeometry.triangleFrom(vector1: firstPoint.position, vector2: thirdPoint.position, vector3: fourthPoint.position)
let triangle2Node = SCNNode(geometry: triangle2)
triangle2Node.geometry?.firstMaterial?.diffuse.contents = UIColor.blue
triangle2Node.geometry?.firstMaterial?.isDoubleSided = true
sceneView.scene.rootNode.addChildNode(triangle2Node)
This is all based on creating 2 initial nodes by selecting the bottom 2 points of a wall in ARKit.
Hope that makes sense to anybody else searching for a similar answer.
EDIT: Adding a Material
Here's a slightly different extension and the code to add a material to it, the end result of a wall remains the same:
extension SCNGeometry {
class func Quad() -> SCNGeometry {
let verticesPosition = [
SCNVector3(x: -0.242548823, y: -0.188490361, z: -0.0887458622),
SCNVector3(x: -0.129298389, y: -0.188490361, z: -0.0820985138),
SCNVector3(x: -0.129298389, y: 0.2, z: -0.0820985138),
SCNVector3(x: -0.242548823, y: 0.2, z: -0.0887458622)
]
let textureCord = [
CGPoint(x: 1, y: 1),
CGPoint(x: 0, y: 1),
CGPoint(x: 0, y: 0),
CGPoint(x: 1, y: 0),
]
let indices: [CInt] = [
0, 2, 3,
0, 1, 2
]
let vertexSource = SCNGeometrySource(vertices: verticesPosition)
let srcTex = SCNGeometrySource(textureCoordinates: textureCord)
let date = NSData(bytes: indices, length: MemoryLayout<CInt>.size * indices.count)
let scngeometry = SCNGeometryElement(data: date as Data,
primitiveType: SCNGeometryPrimitiveType.triangles, primitiveCount: 2,
bytesPerIndex: MemoryLayout<CInt>.size)
let geometry = SCNGeometry(sources: [vertexSource,srcTex],
elements: [scngeometry])
return geometry
}
}
Then simply call it in viewDidLoad() and apply a material
let scene = SCNScene()
let quad = SCNGeometry.Quad()
let (min, max) = quad.boundingBox
let width = CGFloat(max.x - min.x)
let height = CGFloat(max.y - min.y)
quad.firstMaterial?.diffuse.contents = UIImage(named: "wallpaper.jpg")
quad.firstMaterial?.diffuse.contentsTransform = SCNMatrix4MakeScale(Float(width), Float(height), 1)
quad.firstMaterial?.diffuse.wrapS = SCNWrapMode.repeat
quad.firstMaterial?.diffuse.wrapT = SCNWrapMode.repeat
let node = SCNNode()
node.geometry = quad
scene.rootNode.addChildNode(node)
sceneView.scene = scene