关于 iOS 的技术解读有很多,但是却鲜有设备可视化同步的介绍文章。本文一起了解下这个酷炫的 iOS 黑科技。
我们的任务很简单——如上图所示,实时获取设备的当前方向。
UIDevice.current.orientation
首先,需要调用
beginGeneratingDeviceOrientationNotifications()
但仅仅这样还不行。因为如果设备上的旋转被锁定了,那么就不会产生以上通知。我的相机应用程序从头到尾都需要知道方向——所以我意识到我需要直接根据设备的加速度计算方向。
好了,现在有了这些值,我们该做些什么呢?这是一个较难的部分。如果将所有内容都输出到控制台,那么我们很快就会被大量数据淹没。我认为还是在屏幕上显示这些值比较好。
但是,等等,如果将数值显示在图表上,会怎么样?别想图表了,我们可以来用开源的 Blender 试试,它可以实现这些值的可视化,并且很容易扩展。
然而 Blender 并不是很好的代码编辑器,所以我们还是使用钟爱的外部编辑器吧。为了调用外部文件,我们可以将 print("hi") 替换成以下代码:
import bpy import os filename = os.path.join(os.path.dirname(bpy.data.filepath), "server.py") exec(compile(open(filename).read(), filename, 'exec'))
下一步,我们需要在与 .blend 文件相同的文件夹中创建新的 server.py 文件,我们真正的代码就要保存在这里。现在我们可以用任何编辑器打开它,你可以选择 Atom、Sublime,甚至 Word 2007 都行。
找到该 Cube 对象,点击右键并选择重命名,重命名为 iPhone。现在让我们再来看一看 server.py。
import socket import select import json import threading import traceback class ServerThread(threading.Thread): def __init__(self): threading.Thread.__init__(self) self.running = True def stopServer(self): self.running = False self.server.running = False def run(self): try: self.server = Server() while self.running: self.server.receive() except: pass class Server: def __init__(self): self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) self.socket.setblocking(False) self.socket.bind((str(socket.INADDR_ANY), 9845)) self.socket.listen(2) self.running = True def __exit__(self, exc_type, exc_value, traceback): self.socket.close() def receive(self): pairs = [] timeout = 1 while self.running: sockets = list(map(lambda x: x[0], pairs)) if len(pairs) > 0: read_sockets, write_sockets, error_sockets = select.select(sockets, [], [], timeout) for sock in read_sockets: data = sock.recv(4096) if not data : print('Client disconnected') pairs = [] else : self.connectionReceivedData(connection, data.decode()) try: try: connection,address = self.socket.accept() print("new connection: ", connection) pairs.append((connection, address)) except: pass except: pass for pair in pairs: (connection, address) = pair connection.close() def connectionReceivedData(self, connection, data): try: motionData = json.loads(data) except json.decoder.JSONDecodeError: print("Invalid JSON: ", data) return None receivedMotionData(motionData) # This is a global so when we run the script again, we can keep the server alive # but change how it works import bpy def receivedMotionData(motionData): phone = bpy.context.scene.objects["iPhone"] phone.rotation_quaternion.x = float(motionData['x']) phone.rotation_quaternion.y = 0 - float(motionData['z']) phone.rotation_quaternion.z = float(motionData['y']) phone.rotation_quaternion.w = float(motionData['w']) pass try: if serverThread.running == False: serverThread = ServerThread() serverThread.start() print("Starting server") else: print("Server already running, using new motion handler.") except: serverThread = ServerThread() serverThread.start() print("Starting server")
检查 Blender,你应该看到 iPhone 根本没有改变。这是因为上面的脚本使用四元组设置了 iPhone 的旋转角度,并且它使用了欧拉角进行旋转。需要做一些修改。将 Python 控制台面切换到 “Properties”,然后单击该面板顶部的橙色立方体图标。中部 Transform 的下面,点击 XYZ Euler 并选择 Quaternion。现在尝试再次运行 client.py。
你应该看到 iPhone 立即翻转过来了。不要惊慌,这就是我们想要的。现在,我们需要让这个模型跟着实际的 iPhone 旋转。
我们需要将运动数据从 iPhone 发送到运行 Blender 的计算机。感谢上苍我们不需要深入到 Swift 中的原始 C 套接字级别,因为 Foundation 具有抽象。
我们可以将以下代码放入新的 iOS 项目中,以替换默认的 ViewController。请确保使用计算机的本地 IP 地址替换 host 变量。
import UIKit import CoreMotion class CoreMotionViewController: UIViewController, StreamDelegate { let motionManager = CMMotionManager() let queue = OperationQueue() let host = "192.168.1.2" override func viewDidLoad() { super.viewDidLoad() setUpStreams(host: host) motionManager.startDeviceMotionUpdates(to: queue) { (data: CMDeviceMotion?, error: Error?) in guard let data = data else { print("Error: \(error!)") return } let attitude: CMAttitude = data.attitude let quaternion = attitude.quaternion var motionData = MotionData() motionData.x = quaternion.x motionData.y = quaternion.y motionData.z = quaternion.z motionData.w = quaternion.w let encoder = JSONEncoder() do { let json = try encoder.encode(motionData) self.send(data: json) } catch let error { print("Couldn't send data, error: \(error)") } } } // MARK: - Streams var inputStream: InputStream? var outputStream: OutputStream? func setUpStreams(host: String) { var readStream: Unmanaged<CFReadStream>? var writeStream: Unmanaged<CFWriteStream>? CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, host as CFString, 9845, &readStream, &writeStream) inputStream = readStream!.takeRetainedValue() outputStream = writeStream!.takeRetainedValue() guard let inputStream = inputStream, let outputStream = outputStream else { print("Failed to create streams") return } inputStream.delegate = self outputStream.delegate = self inputStream.schedule(in: .current, forMode: .commonModes) outputStream.schedule(in: .current, forMode: .commonModes) inputStream.open() outputStream.open() } func send(data: Data) { guard let outputStream = outputStream else { return } _ = data.withUnsafeBytes { outputStream.write($0, maxLength: data.count) } } func stream(_ aStream: Stream, handle eventCode: Stream.Event) { if eventCode == .errorOccurred { inputStream = nil outputStream = nil print("Error: Stream error") } else if eventCode == .endEncountered { inputStream = nil outputStream = nil print("Error: Encountered end of stream") } let maxReadLength = 4096 if eventCode == .hasBytesAvailable { guard let inputStream = inputStream else { return } while inputStream.hasBytesAvailable { let buffer = UnsafeMutablePointer<UInt8>.allocate(capacity: maxReadLength) inputStream.read(buffer, maxLength: maxReadLength) buffer.deallocate() } } } } // MARK: - Data Model private struct MotionData: Codable { var x: Double = 0 var y: Double = 0 var z: Double = 0 var w: Double = 0 }
那么最终我是如何从移动管理器获取方向信息的?
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