ARKit(SpriteKit) 臉部角度追蹤

1. 建立😘 。由於前鏡頭左右相反，所以X軸要反向。

   let labelNode = SKLabelNode(text: "😘")

   labelNode.horizontalAlignmentMode = .center

   labelNode.verticalAlignmentMode = .center

   labelNode.xScale = -1

2. 須將😘放入SKTransformNode，做後續的3D轉換。
   

   let face = SKTransformNode()

   face.addChild(labelNode)

   self.face = face

3. 更新時，SKTransformNode再依據ARFaceAnchor旋轉
   

   let rotate = faceAnchor.transform.rotate

   face?.setRotationMatrix(rotate)

4. 最後，記得將node轉回來，否則貼圖會是反的

完整程式

extension matrix_float4x4 {

    var rotate: matrix_float3x3 {

        let (a,b,c,_) = columns

        return float3x3(a.xyz, b.xyz, c.xyz)

    }

}

extension SIMD4 {

    var xyz: SIMD3<Scalar> {

        return SIMD3(x, y, z)

    }

}

var face: SKTransformNode?

func view(_ view: ARSKView, nodeFor anchor: ARAnchor) -> SKNode? {

    // Create and configure a node for the anchor added to the view's session.

    if anchor is ARFaceAnchor {

        let labelNode = SKLabelNode(text: "😘")

        labelNode.horizontalAlignmentMode = .center

        labelNode.verticalAlignmentMode = .center

        labelNode.xScale = -3

        labelNode.yScale = 3

        

        let face = SKTransformNode()

        face.addChild(labelNode)

        self.face = face

        

        let node = SKNode()

        node.addChild(face)

        return node

    }

    return nil

}

func view(_ view: ARSKView, didUpdate node: SKNode, for anchor: ARAnchor){

    if let faceAnchor = anchor as? ARFaceAnchor  {

        let rotate = faceAnchor.transform.rotate

        face?.setRotationMatrix(rotate)

        node.xScale *= -1

    }

}