unity3D实现摄像机抖动特效

public class CameraShake : MonoBehaviour
 {
 /// 
 /// The cameras to shake.
 /// 
 public List cameras   = new List();
 /// 
 /// The maximum number of shakes to perform.
 /// 
 public int numberOfShakes   = 2;
 /// 
 /// The amount to shake in each direction.
 /// 
 public Vector3 shakeAmount   = Vector3.one;
 /// 
 /// The amount to rotate in each direction.
 /// 
 public Vector3 rotationAmount   = Vector3.one;
 /// 
 /// The initial distance for the first shake.
 /// 
 public float distance   = 00.10f;
 /// 
 /// The speed multiplier for the shake.
 /// 
 public float speed   = 50.00f;
 /// 
 /// The decay speed (between 0 and 1). Higher values will stop shaking sooner.
 /// 
 public float decay   = 00.20f;
 /// 
 /// The modifier applied to speed in order to shake the GUI.
 /// 
 public float guiShakeModifier   = 01.00f;
 /// 
 /// If true, multiplies the final shake speed by the time scale.
 /// 
 public bool multiplyByTimeScale   = true;
 
 // Shake rect (for GUI)
 private Rect shakeRect;
 
 // States
 private bool shaking   = false;
 private bool cancelling   = false;
 
 internal class ShakeState
 {
 internal readonly Vector3 startPosition;
 internal readonly Quaternion startRotation;
 internal readonly Vector2 guiStartPosition;
 internal Vector3 shakePosition;
 internal Quaternion shakeRotation;
 internal Vector2 guiShakePosition;
 
 internal ShakeState(Vector3 position, Quaternion rotation, Vector2 guiPosition)
 {
 startPosition = position;
 startRotation = rotation;
 guiStartPosition = guiPosition;
 shakePosition = position;
 shakeRotation = rotation;
 guiShakePosition = guiPosition;
 }
 }
 private Dictionary> states = new Dictionary>();
 private Dictionary shakeCount  = new Dictionary();
 
 // Minimum shake values
 private const bool checkForMinimumValues  = true;
 private const float minShakeValue  = 0.001f;
 private const float minRotationValue  = 0.001f;
 
 #region Singleton
 /// 
 /// The Camera Shake singleton instance.
 /// 
 public static CameraShake instance; 
 private void OnEnable()
 {
 if (cameras.Count < 1)
 {
 if (camera)
  cameras.Add(camera);
 }
 
 if (cameras.Count < 1)
 {
 if (Camera.main)
  cameras.Add(Camera.main);
 }
 
 if (cameras.Count < 1)
 {
 Debug.LogError("Camera Shake: No cameras assigned in the inspector!");
 }
 instance = this;
 }
 #endregion
 
 #region Static properties
 public static bool isShaking
 {
 get
 {
 return instance.IsShaking();
 }
 }
 public static bool isCancelling
 {
 get
 {
 return instance.IsCancelling();
 }
 }
 #endregion
 
 #region Static methods
 public static void Shake()
 {
 instance.DoShake();
 } 
 public static void Shake(int numberOfShakes, Vector3 shakeAmount, Vector3 rotationAmount, float distance, float speed, float decay, float guiShakeModifier, bool multiplyByTimeScale)
 {
 instance.DoShake(numberOfShakes, shakeAmount, rotationAmount, distance, speed, decay, guiShakeModifier, multiplyByTimeScale);
 }
 public static void Shake(System.Action callback)
 {
 instance.DoShake(callback);
 } 
 public static void Shake(int numberOfShakes, Vector3 shakeAmount, Vector3 rotationAmount, float distance, float speed, float decay, float guiShakeModifier, bool multiplyByTimeScale, System.Action callback)
 {
 instance.DoShake(numberOfShakes, shakeAmount, rotationAmount, distance, speed, decay, guiShakeModifier, multiplyByTimeScale, callback);
 }
 public static void CancelShake()
 {
 instance.DoCancelShake();
 }
 public static void CancelShake(float time)
 {
 instance.DoCancelShake(time);
 }
 
 public static void BeginShakeGUI()
 {
 instance.DoBeginShakeGUI();
 }
 public static void EndShakeGUI()
 {
 instance.DoEndShakeGUI();
 } 
 public static void BeginShakeGUILayout()
 {
 instance.DoBeginShakeGUILayout();
 } 
 public static void EndShakeGUILayout()
 {
 instance.DoEndShakeGUILayout();
 }
 #endregion
 
 #region Events
 /// 
 /// Occurs when a camera starts shaking.
 /// 
 public event System.Action cameraShakeStarted; 
 /// 
 /// Occurs when a camera has completely stopped shaking and has been reset to its original position.
 /// 
 public event System.Action allCameraShakesCompleted;
 #endregion
 
 #region Public methods
 public bool IsShaking()
 { 
 return shaking;
 }
 public bool IsCancelling()
 {
 return cancelling;
 }
 public void DoShake()
 {
 Vector3 seed = Random.insideUnitSphere;
 
 foreach(Camera cam in cameras)
 {
 StartCoroutine(DoShake_Internal(cam, seed, this.numberOfShakes, this.shakeAmount, this.rotationAmount, this.distance, this.speed, this.decay, this.guiShakeModifier, this.multiplyByTimeScale, null));
 }
 }
 public void DoShake(int numberOfShakes, Vector3 shakeAmount, Vector3 rotationAmount, float distance, float speed, float decay, float guiShakeModifier, bool multiplyByTimeScale)
 {
 Vector3 seed = Random.insideUnitSphere;
 
 foreach(Camera cam in cameras)
 {
 StartCoroutine(DoShake_Internal(cam, seed, numberOfShakes, shakeAmount, rotationAmount, distance, speed, decay, guiShakeModifier, multiplyByTimeScale, null));
 }
 }
 public void DoShake(System.Action callback)
 {
 Vector3 seed = Random.insideUnitSphere;
 
 foreach(Camera cam in cameras)
 {
 StartCoroutine(DoShake_Internal(cam, seed, this.numberOfShakes, this.shakeAmount, this.rotationAmount, this.distance, this.speed, this.decay, this.guiShakeModifier, this.multiplyByTimeScale, callback));
 }
 }
 public void DoShake(int numberOfShakes, Vector3 shakeAmount, Vector3 rotationAmount, float distance, float speed, float decay, float guiShakeModifier, bool multiplyByTimeScale, System.Action callback)
 {
 Vector3 seed = Random.insideUnitSphere;
 
 foreach(Camera cam in cameras)
 {
 StartCoroutine(DoShake_Internal(cam, seed, numberOfShakes, shakeAmount, rotationAmount, distance, speed, decay, guiShakeModifier, multiplyByTimeScale, callback));
 }
 }
 public void DoCancelShake()
 {
 if (shaking && !cancelling)
 {
 shaking = false;
 this.StopAllCoroutines();
 foreach(Camera cam in cameras)
 {
  if (shakeCount.ContainsKey(cam))
  {
  shakeCount[cam] = 0;
  }
  ResetState(cam.transform, cam);
 }
 }
 }
 public void DoCancelShake(float time)
 {
 if (shaking && !cancelling)
 {
 this.StopAllCoroutines();
 this.StartCoroutine(DoResetState(cameras, shakeCount, time));
 }
 }
 public void DoBeginShakeGUI()
 {
 CheckShakeRect();
 GUI.BeginGroup(shakeRect);
 }
 public void DoEndShakeGUI()
 {
 GUI.EndGroup();
 } 
 public void DoBeginShakeGUILayout()
 {
 CheckShakeRect();
 GUILayout.BeginArea(shakeRect);
 } 
 public void DoEndShakeGUILayout()
 {
 GUILayout.EndArea();
 }
 #endregion
 
 #region Private methods
 private void OnDrawGizmosSelected()
 { 
 foreach(Camera cam in cameras)
 {
 if (!cam)
  continue;
 
 if (IsShaking())
 {
  Vector3 offset = cam.worldToCameraMatrix.GetColumn(3);
  offset.z *= -1;
  offset = cam.transform.position + cam.transform.TransformPoint(offset);
  Quaternion rot = QuaternionFromMatrix(cam.worldToCameraMatrix.inverse * Matrix4x4.TRS(Vector3.zero, Quaternion.identity, new Vector3(1,1,-1)));
  Matrix4x4 matrix = Matrix4x4.TRS(offset, rot, cam.transform.lossyScale);
  Gizmos.matrix = matrix; 
 }
 else
 {
  Matrix4x4 matrix = Matrix4x4.TRS(cam.transform.position, cam.transform.rotation, cam.transform.lossyScale);
  Gizmos.matrix = matrix;
 }
 
 Gizmos.DrawWireCube(Vector3.zero, shakeAmount);
 
 Gizmos.color = Color.cyan;
 
 if (cam.isOrthoGraphic)
 {
  Vector3 pos = new Vector3(0, 0, (cam.near + cam.far) / 2f);
  Vector3 size = new Vector3(cam.orthographicSize / cam.aspect, cam.orthographicSize * 2f, cam.far - cam.near);
  Gizmos.DrawWireCube(pos, size);
 }
 else
 {
  Gizmos.DrawFrustum(Vector3.zero, cam.fov, cam.far, cam.near, (.7f / cam.aspect));
 }
 }
 }
 
 private IEnumerator DoShake_Internal(Camera cam, Vector3 seed, int numberOfShakes, Vector3 shakeAmount, Vector3 rotationAmount, float distance, float speed, float decay, float guiShakeModifier, bool multiplyByTimeScale, System.Action callback)
 {
 // Wait for async cancel operations to complete
 if (cancelling)
 yield return null;
 
 // Set random values
 var mod1 = seed.x > .5f ? 1 : -1;
 var mod2 = seed.y > .5f ? 1 : -1;
 var mod3 = seed.z > .5f ? 1 : -1;
 
 // First shake
 if (!shaking)
 {
 shaking = true;
 
 if (cameraShakeStarted != null)
  cameraShakeStarted();
 }
 
 if (shakeCount.ContainsKey(cam))
 shakeCount[cam]++;
 else
 shakeCount.Add(cam, 1);
 
 // Pixel width is always based on the first camera
 float pixelWidth = GetPixelWidth(cameras[0].transform, cameras[0]);
 
 // Set other values
 Transform cachedTransform = cam.transform;
 Vector3 camOffset = Vector3.zero;
 Quaternion camRot = Quaternion.identity;
 
 int currentShakes = numberOfShakes;
 float shakeDistance = distance;
 float rotationStrength = 1;
 
 float startTime = Time.time;
 float scale = multiplyByTimeScale ? Time.timeScale : 1;
 float pixelScale = pixelWidth * guiShakeModifier * scale;
 Vector3 start1 = Vector2.zero;
 Quaternion startR = Quaternion.identity;
 Vector2 start2 = Vector2.zero;
 
 ShakeState state = new ShakeState(cachedTransform.position, cachedTransform.rotation, new Vector2(shakeRect.x, shakeRect.y));
 List stateList;
 
 if (states.TryGetValue(cam, out stateList))
 {
 stateList.Add(state);
 }
 else
 {
 stateList = new List();
 stateList.Add(state);
 states.Add(cam, stateList);
 }
 
 // Main loop
 while (currentShakes > 0)
 { 
 if (checkForMinimumValues)
 {
  // Early break when rotation is less than the minimum value.
  if (rotationAmount.sqrMagnitude != 0 && rotationStrength <= minRotationValue)
  break;
  
  // Early break when shake amount is less than the minimum value.
  if (shakeAmount.sqrMagnitude != 0 && distance != 0 && shakeDistance <= minShakeValue)
  break;
 }
 
 var timer = (Time.time - startTime) * speed;
 
 state.shakePosition = start1 + new Vector3(
  mod1 * Mathf.Sin(timer) * (shakeAmount.x * shakeDistance * scale), 
  mod2 * Mathf.Cos(timer) * (shakeAmount.y * shakeDistance * scale), 
  mod3 * Mathf.Sin(timer) * (shakeAmount.z * shakeDistance * scale));
 
 state.shakeRotation = startR * Quaternion.Euler(
  mod1 * Mathf.Cos(timer) * (rotationAmount.x * rotationStrength * scale), 
  mod2 * Mathf.Sin(timer) * (rotationAmount.y * rotationStrength * scale), 
  mod3 * Mathf.Cos(timer) * (rotationAmount.z * rotationStrength * scale));
 
 state.guiShakePosition = new Vector2(
  start2.x - (mod1 * Mathf.Sin(timer) * (shakeAmount.x * shakeDistance * pixelScale)),
  start2.y - (mod2 * Mathf.Cos(timer) * (shakeAmount.y * shakeDistance * pixelScale)));
 
 camOffset = GetGeometricAvg(stateList, true);
 camRot = GetAvgRotation(stateList); 
 NormalizeQuaternion(ref camRot);
 
 Matrix4x4 m = Matrix4x4.TRS(camOffset, camRot, new Vector3(1, 1, -1));
   
 cam.worldToCameraMatrix = m * cachedTransform.worldToLocalMatrix;
 
 var avg = GetGeometricAvg(stateList, false);
 
 shakeRect.x = avg.x;
 shakeRect.y = avg.y;
 
 if (timer > Mathf.PI * 2)
 {
  startTime = Time.time;
  shakeDistance *= (1 - Mathf.Clamp01(decay));
  rotationStrength *= (1 - Mathf.Clamp01(decay));
  currentShakes--;
 }
 yield return null;
 }
 
 // End conditions
 
 shakeCount[cam]--;
 
 // Last shake
 if (shakeCount[cam] == 0)
 {
 shaking = false;
 ResetState(cam.transform, cam);
 
 if (allCameraShakesCompleted != null)
 {
  allCameraShakesCompleted();
 }
 }
 else
 {
 stateList.Remove(state);
 }
 
 if (callback != null)
 callback();
 }
 private Vector3 GetGeometricAvg(List states, bool position)
 { 
 float x = 0, y = 0, z = 0, l = states.Count;
 
 foreach(ShakeState state in states)
 {
 if (position)
 {
  x -= state.shakePosition.x;
  y -= state.shakePosition.y;
  z -= state.shakePosition.z;
 }
 else
 {
  x += state.guiShakePosition.x;
  y += state.guiShakePosition.y;
 }
 }
 
 return new Vector3(x / l, y / l, z / l);
 } 
 private Quaternion GetAvgRotation(List states)
 {
 Quaternion avg = new Quaternion(0,0,0,0);
 
 foreach(ShakeState state in states)
 {
 if (Quaternion.Dot (state.shakeRotation, avg) > 0)
 {
  avg.x += state.shakeRotation.x;
  avg.y += state.shakeRotation.y;
  avg.z += state.shakeRotation.z;
  avg.w += state.shakeRotation.w;
 }
 else
 {
  avg.x += -state.shakeRotation.x;
  avg.y += -state.shakeRotation.y;
  avg.z += -state.shakeRotation.z;
  avg.w += -state.shakeRotation.w;
 }
 }
 
 var mag = Mathf.Sqrt(avg.x* avg.x + avg.y* avg.y + avg.z * avg.z + avg.w * avg.w);
 
 if (mag > 0.0001f)
 {
 avg.x /= mag;
 avg.y /= mag;
 avg.z /= mag;
 avg.w /= mag;
 }
 else
 {
 avg = states[0].shakeRotation;
 }
 
 return avg;
 }
 private void CheckShakeRect()
 {
 if (Screen.width != shakeRect.width || Screen.height != shakeRect.height)
 {
 
 shakeRect.width = Screen.width;
 shakeRect.height = Screen.height;
 }
 }
 private float GetPixelWidth(Transform cachedTransform, Camera cachedCamera)
 {
 var position = cachedTransform.position;
 var screenPos = cachedCamera.WorldToScreenPoint(position - cachedTransform.forward * .01f);
 var offset = Vector3.zero;
 
 if (screenPos.x > 0)
 offset = screenPos - Vector3.right;
 else
 offset = screenPos + Vector3.right;
 
 if (screenPos.y > 0)
 offset = screenPos - Vector3.up;
 else
 offset = screenPos + Vector3.up;
 
 offset = cachedCamera.ScreenToWorldPoint(offset);
 
 return 1f / (cachedTransform.InverseTransformPoint(position) - cachedTransform.InverseTransformPoint(offset)).magnitude;
 }
 private void ResetState(Transform cachedTransform, Camera cam)
 {
 cam.ResetWorldToCameraMatrix();
 
 shakeRect.x = 0;
 shakeRect.y = 0;
 
 states[cam].Clear();
 }
 private List offsetCache = new List(10);
 private List rotationCache = new List(10);
 private IEnumerator DoResetState(List cameras, Dictionary shakeCount, float time)
 {
 offsetCache.Clear();
 rotationCache.Clear();
 
 foreach(Camera cam in cameras)
 {
 offsetCache.Add((Vector3)((cam.worldToCameraMatrix * cam.transform.worldToLocalMatrix.inverse).GetColumn(3)));
 rotationCache.Add(QuaternionFromMatrix((cam.worldToCameraMatrix * cam.transform.worldToLocalMatrix.inverse).inverse * Matrix4x4.TRS(Vector3.zero, Quaternion.identity, new Vector3(1,1,-1))));
 
 if (shakeCount.ContainsKey(cam))
 {
  shakeCount[cam] = 0;
 }
 states[cam].Clear();
 }
 
 float t = 0;
 float x = shakeRect.x, y = shakeRect.y;
 cancelling = true;
 while (t < time)
 {
 int i = 0;
 foreach(Camera cam in cameras)
 {
  Transform cachedTransform = cam.transform;
 
  shakeRect.x = Mathf.Lerp(x, 0, t / time);
  shakeRect.y = Mathf.Lerp(y, 0, t / time);
 
  Vector3 pos = Vector3.Lerp(offsetCache[i], Vector3.zero, t / time);
  Quaternion rot = Quaternion.Slerp(rotationCache[i], cachedTransform.rotation, t / time);
  Matrix4x4 m = Matrix4x4.TRS(pos, rot, new Vector3(1, 1, -1));
 
  cam.worldToCameraMatrix = m * cachedTransform.worldToLocalMatrix;
  i++;
 }
 t += Time.deltaTime;
 yield return null;
 }
 
 foreach(Camera cam in cameras)
 {
 cam.ResetWorldToCameraMatrix();
 shakeRect.x = 0;
 shakeRect.y = 0;
 }
 this.shaking = false;
 this.cancelling = false;
 }
 #endregion
 
 #region Quaternion helpers
 private static Quaternion QuaternionFromMatrix(Matrix4x4 m)
 {
 return Quaternion.LookRotation(m.GetColumn(2), m.GetColumn(1));
 }
 private static void NormalizeQuaternion (ref Quaternion q) 
 {
 float sum = 0; 
 
 for (int i = 0; i < 4; ++i)
 sum += q[i] * q[i];
 
 float magnitudeInverse = 1 / Mathf.Sqrt(sum);
 
 for (int i = 0; i < 4; ++i)
 q[i] *= magnitudeInverse;
 }
 #endregion
 }