CODEWITHSUNDEEP
iosswiftarkit
Villainsoft
Villainsoft

Reputation: 147

ARKit - Center SCNode on camera

With ARKit/Scenekit, I am looking to add a 2D image mapped onto a plane node into a scene, but I want this node to continually center on the user/camera.

Here is my function for adding the node at the initial 0,0,0 location.

let plane = SCNPlane(width: 20, height: 20)
let material = SCNMaterial()
material.isDoubleSided = true
material.diffuse.contents = UIImage(named: "CompassRose.png")
plane.materials = [material]

NodeCompass  = SCNNode(geometry: plane)
NodeCompass.position = SCNVector3Make(0,0,0) 

skScene.rootNode.addChildNode(NodeCompass)

The trick is to modify the position of this node when the users location changes. How is this done?

Upvotes: 2

Views: 1516

Answers (1)

Willjay
Willjay

Reputation: 6459

To keep your node always in the center of view, you have to calculate the center position of world position.

extension ARSCNView {
    // create real world position of the point
    func realWorldPosition(for point: CGPoint) -> SCNVector3? {
        let result = self.hitTest(point, types: [.featurePoint])
        guard let hitResult = result.last else { return nil }
        let hitTransform = SCNMatrix4(hitResult.worldTransform)

        // m4x -> position ;; 1: x, 2: y, 3: z
        let hitVector = SCNVector3Make(hitTransform.m41, hitTransform.m42, hitTransform.m43)

        return hitVector
    }
}

// MARK: - ARSCNViewDelegate
func renderer(_ renderer: SCNSceneRenderer, updateAtTime time: TimeInterval) {
    DispatchQueue.main.async {
        let center = self.view.center
        guard let realWorldPosition = self.sceneView.realWorldPosition(for: center) else { return }
        self.NodeCompass.position = realWorldPosition
    }
}

Upvotes: 4

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