Last updated
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
// 確保可以取得當前session的frame
guard let currentFrame = sceneView.session.currentFrame else { return }
// 影像的處理是非常耗CPU，千萬不要放在main thread中
DispatchQueue.global(qos: .background).async {
do {
// VNDetectRectanglesRequest只有一個參數，那就是一個closure
// 這個closure負責當影像分析完畢的callback
// VNDetectRectanglesRequest最多只會回傳一個result, 因為他的一個屬性maximumObservations的預設值是1
let request = VNDetectRectanglesRequest { (request, error) in
// 利用compactMap將[Any]轉成[VNRectangleObservation]
guard let results = request.results?.compactMap({ $0 as? VNRectangleObservation }),
let result = results.first else {
// 沒有找到任何Rectangles形狀
print("[Vision] VNRequest produced no result ")
return
}
// 透過Vison只能取得2D image的特征
// 利用VNRectangleObservation的4個property(2D特徵), 透過ARKit中提供的hitTest轉化成3Ｄ空間的座標
let coordinates: [matrix_float4x4] = [
result.topLeft,
result.topRight,
result.bottomRight,
result.bottomLeft
].compactMap {
// currentFrame.hitTest(_:types:) projects a point to a 3D object
guard let hitFeature = currentFrame.hitTest($0, types: .featurePoint).first else { return nil }
return hitFeature.worldTransform
}
guard coordinates.count == 4 else { return }
DispatchQueue.main.async {
// 如果有先前的Billboard存在，那先移除掉
self.removeBillboard()
let (topLeft, topRight, bottomRight, bottomLeft) =
(coordinates[0], coordinates[1], coordinates[2], coordinates[3])
self.createBillboard(topLeft: topLeft, topRight: topRight,
bottomRight: bottomRight, bottomLeft: bottomLeft)
}
}
// 執行request
let handler = VNImageRequestHandler(cvPixelBuffer: currentFrame.capturedImage)
try handler.perform([request])
} catch(let error) {
print("An error occurred during rectangle detection: \(error)")
}
}
} func createBillboard(topLeft: matrix_float4x4, topRight: matrix_float4x4, bottomRight: matrix_float4x4, bottomLeft: matrix_float4x4) {
// 利用matrix產生RectangularPlane
let plane = RectangularPlane(topLeft: topLeft, topRight: topRight, bottomLeft: bottomLeft, bottomRight: bottomRight)
let anchor = ARAnchor(transform: plane.center)
billboard = BillboardContainer(billboardAnchor: anchor, plane: plane)
sceneView.session.add(anchor: anchor)
print("New billboard created")
}
func removeBillboard() {
if let anchor = billboard?.billboardAnchor {
sceneView.session.remove(anchor: anchor)
billboard?.billboardNode?.removeFromParentNode()
billboard = nil
}
} // Debug, 顯示偵測到平面的四個方塊角落
for coordinate in coordinates {
let box = SCNBox(width: 0.01, height: 0.01, length: 0.01, chamferRadius: 0)
let node = SCNNode(geometry: box)
node.transform = SCNMatrix4(coordinate)
self.sceneView.scene.rootNode.addChildNode(node)
}extension AdViewController: ARSCNViewDelegate {
// 將ARKit的anchor轉成SceneKit node
func renderer(_ renderer: SCNSceneRenderer, nodeFor anchor: ARAnchor) -> SCNNode? {
guard let billboard = billboard else { return nil }
var node: SCNNode? = nil
DispatchQueue.main.async {
switch anchor {
case billboard.billboardAnchor:
let billboardNode = self.addBillboardNode()
node = billboardNode
default:
break
}
}
return node
}
}
func addBillboardNode() -> SCNNode? {
guard let billboard = billboard else { return nil }
let rectangle = SCNPlane(width: billboard.plane.width, height: billboard.plane.height)
let rectangleNode = SCNNode(geometry: rectangle)
self.billboard?.billboardNode = rectangleNode
return rectangleNode
}