基于Unity3D的相机功能的实现（一）——VR相机

Unity自带陀螺仪功能，今天就利用陀螺仪实现一个VR相机功能。步骤如下：

1. 打开Unity，创建一个新的C#脚本GyroController.cs,并挂在MainCamera游戏对象上，代码如下：

   using UnityEngine;
   using System.Collections;
   
   public class GyroController : MonoBehaviour
   {
       // Fields
       private readonly Quaternion baseIdentity = Quaternion.Euler(90f, 0f, 0f);
       private Quaternion baseOrientation = Quaternion.Euler(90f, 0f, 0f);
       private Quaternion baseOrientationRotationFix = Quaternion.identity;
       private Quaternion calibration = Quaternion.identity;
       private Quaternion cameraBase = Quaternion.identity;
       private bool debug = true;
       public static bool gyroAvaiable;
       private bool gyroEnabled = true;
       private Quaternion gyroInitialRotation;
       public static bool gyroOff;
       private Quaternion initialRotation;
       private readonly Quaternion landscapeLeft = Quaternion.Euler(0f, 0f, -90f);
       private readonly Quaternion landscapeRight = Quaternion.Euler(0f, 0f, 90f);
       private const float lowPassFilterFactor = 0.1f;
       private Quaternion offsetRotation;
       private Quaternion referanceRotation = Quaternion.identity;
       private readonly Quaternion upsideDown = Quaternion.Euler(0f, 0f, 180f);
   
       // Methods
       private void AttachGyro()
       {
           this.gyroEnabled = true;
           this.ResetBaseOrientation();
           this.UpdateCalibration(true);
           this.UpdateCameraBaseRotation(true);
           this.RecalculateReferenceRotation();
       }
   
       private void Awake()
       {
           gyroAvaiable = SystemInfo.supportsGyroscope;
       }
   
       private static Quaternion ConvertRotation(Quaternion q)
       {
           return new Quaternion(q.x, q.y, -q.z, -q.w);
       }
   
       private void DetachGyro()
       {
           this.gyroEnabled = false;
       }
   
       private Quaternion GetRotFix()
       {
           return Quaternion.identity;
       }
   
       private void RecalculateReferenceRotation()
       {
           this.referanceRotation = Quaternion.Inverse(this.baseOrientation) * Quaternion.Inverse(this.calibration);
       }
   
       private void ResetBaseOrientation()
       {
           this.baseOrientationRotationFix = this.GetRotFix();
           this.baseOrientation = this.baseOrientationRotationFix * this.baseIdentity;
       }
   
       protected void Start()
       {
   
               Input.gyro.enabled = true;
               base.enabled = true;
           this.AttachGyro();
           this.initialRotation = base.transform.localRotation;
           this.gyroInitialRotation = Input.gyro.attitude;
       }
   
       private void Update()
       {
           gyroOff = PlayerPrefs.GetInt("gyro-off") == 1;
           if (this.gyroEnabled )
           {
               base.transform.localRotation = Quaternion.Slerp(base.transform.localRotation, this.cameraBase * (ConvertRotation(this.referanceRotation * Input.gyro.attitude) * this.GetRotFix()), 0.5f);//0.1f
           }
       }
   
       private void UpdateCalibration(bool onlyHorizontal)
       {
           if (onlyHorizontal)
           {
               Vector3 toDirection = (Vector3) (Input.gyro.attitude * -Vector3.forward);
               toDirection.z = 0f;
               if (toDirection == Vector3.zero)
               {
                   this.calibration = Quaternion.identity;
               }
               else
               {
                   this.calibration = Quaternion.FromToRotation((Vector3) (this.baseOrientationRotationFix * Vector3.up), toDirection);
               }
           }
           else
           {
               this.calibration = Input.gyro.attitude;
           }
       }
   
       private void UpdateCameraBaseRotation(bool onlyHorizontal)
       {
           if (onlyHorizontal)
           {
               Vector3 forward = base.transform.forward;
               forward.y = 0f;
               if (forward == Vector3.zero)
               {
                   this.cameraBase = Quaternion.identity;
               }
               else
               {
                   this.cameraBase = Quaternion.FromToRotation(Vector3.forward, forward);
               }
           }
           else
           {
               this.cameraBase = base.transform.rotation;
           }
       }
   }

2. 在相机MainCamera下创建一个新的Camera相机，并改变两个相机的Viewport Rect属性，以将屏幕均分，如图：
3. 在场景中创建一个Cube，效果如图：
4. 保存场景，打包成apk，安装到手机即可。