How to change orientation of a SCNNode to the Camera with ARKit

Question

The code below places a SCNPlane onto the point touched, but the plane is oriented (rotated) to the position that the phone was in when the app started. I would ideally like to orient the Node to a physical wall or to the current orientation of the camera. How is this done with ARKit?

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touch = touches.first else {return}
    let result = sceneView.hitTest(touch.location(in: sceneView), types: [ARHitTestResult.ResultType.featurePoint])
    guard let hitResult = result.last else {return}
    let hitTransform = SCNMatrix4.init(hitResult.worldTransform)

    let hitVector = SCNVector3Make(hitTransform.m41, hitTransform.m42, hitTransform.m43)
    createPlane(position: hitVector)
}

func createPlane(position: SCNVector3) {

    let background = SCNNode()
    background.geometry = SCNPlane.init(width: 0.12, height: 0.10) // better set its size
    background.geometry?.firstMaterial?.diffuse.contents = "odinBW2.jpeg"
    background.position = position

    sceneView.scene.rootNode.addChildNode(background)

}

In the end I decided to prepare the user with instructions to face the phone in the proper direction before starting the arkit view. — Rob Schlackman, Nov 22 '17 at 10:58

score 11 · Answer 1 · answered Mar 03 '18 at 11:12

11

If you want to align your node to the camera's orientation, just use SCNBillboardConstraint.

let yourNode = SCNNode()

let billboardConstraint = SCNBillboardConstraint()
billboardConstraint.freeAxes = [.X, .Y, .Z]
yourNode.constraints = [billboardConstraint]

answered Mar 03 '18 at 11:12

Jun Tanaka

111
1
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This is pretty awesome. Thanks! – Cesare Dec 16 '18 at 21:27
`billboardConstraint.freeAxes = [.X, .Y, .Z]` is redundant, that's the default (`SCNBillboardAxis.all`). Can just do `yourNode.constraints = [SCNBillboardConstraint()]` – bauerMusic Sep 13 '21 at 06:56

score 7 · Answer 2 · answered Nov 16 '17 at 19:15

7

1 - This is how you get the rotation of the camera first:

Pitch - rotation around the X axis

let pitch = sceneView.session.currentFrame?.camera.eulerAngles.x

Yawn - rotation around the Y axis

let yawn = sceneView.session.currentFrame?.camera.eulerAngles.y

Roll - rotation around the Z axis

let roll = sceneView.session.currentFrame?.camera.eulerAngles.z

2 - And then you can create the SCNVector3 that matches the rotations you want to keep (0 if you don't want any rotation on an axis) :

let newRotation = SCNVector3Make(pitch, yawn, roll)

3 - And then you attribute this eulerAngles to your node:

whateverNode.eulerAngles = newRotation

answered Nov 16 '17 at 19:15

Oscar Falmer

1,771
1
24
38

This works great when the phone is in landscape mode, but not portrait. – Alan Scarpa Mar 28 '18 at 19:22
@Alan_s This works for landscape and portrait, I think you locked your AR to landscape that's why. – Oscar Falmer Mar 29 '18 at 09:01
Is this a setting on ARSceneView or something similar? – Alan Scarpa Mar 29 '18 at 18:05
not work for me in portrait. What you mean by " locked your AR to landscape" – Yair hadad Oct 29 '18 at 12:54

How to change orientation of a SCNNode to the Camera with ARKit

2 Answers2