ARKit & CoreLocation + POI + AR Scene

LocationTextAnnotationNode.swift

open class LocationTextAnnotationNode: LocationNode {
    
    // image and text that are displayed by the child nodes
    public let image: UIImage
    public let text: String
    
    // child nodes
    public let imageAnnotationNode: SCNNode
    public let textAnnotationNode: SCNNode
    
    public init(location: CLLocation?, image: UIImage, text: String) {
        self.text = text
        self.image = image
        
        // create the child node that holds the location's marker image
        let imagePlane = SCNPlane(width: image.size.width / 100, height: image.size.height / 100)
        imagePlane.firstMaterial!.diffuse.contents = image
        imagePlane.firstMaterial!.lightingModel = .constant
        
        imageAnnotationNode = SCNNode()
        imageAnnotationNode.geometry = imagePlane
        
        // create the child node that holds the location's name
        let textShape = SCNText(string: text, extrusionDepth: 1)
        textShape.firstMaterial!.diffuse.contents = UIColor.white
        textShape.firstMaterial!.specular.contents = UIColor.black
        textShape.firstMaterial!.lightingModel = .phong
        textShape.isWrapped = true
        textShape.alignmentMode = CATextLayerAlignmentMode.center.rawValue
        
        textAnnotationNode = SCNNode()
        textAnnotationNode.geometry = textShape
        
        // initializer ARCL's LocationNode
        super.init(location: location)
        scaleRelativeToDistance = true
        
        // apply a billboard constraint so the parent node, so it always faces the user
        let billboardConstraint = SCNBillboardConstraint()
        billboardConstraint.freeAxes = SCNBillboardAxis.Y
        constraints = [billboardConstraint]
        
        // add the child nodes
        addChildNode(imageAnnotationNode)
        addChildNode(textAnnotationNode)
        
        // center text correctly around (x) and below (y) origin (SCNText's origins in in the bottom left corner)
        let min = textAnnotationNode.boundingBox.min
        let max = textAnnotationNode.boundingBox.max
        textAnnotationNode.pivot = SCNMatrix4MakeTranslation((max.x - min.x) / 2, (max.y - min.y), 0);
    }
}