Unity双指旋转
发表于2018-09-16
Input.touchCount为屏幕触摸的数量（2个手指），我们通过双指移动完成旋转操作，所以屏幕上需要至少2个手指并且手指在移动。
思路都是：
每一帧以两指坐标生成一个向量Vector2，不同帧比较向量的角度变化Vector2.Angle()。
简化版：参考EasyTouch的实现
public class TouchTest : MonoBehaviour ｛ Touch oldTouch1; //上次触摸点1(手指1) Touch oldTouch2; //上次触摸点2(手指2) void Update() ｛ if (Input.touchCount <= 1) ｛ return; ｝ Touch touch1 = Input.GetTouch(0); Touch touch2 = Input.GetTouch(1); //启用双指，尚未旋转 if (touch2.phase == TouchPhase.Began) ｛ oldTouch2 = touch2; oldTouch1 = touch1; return; ｝ if (touch1.phase == TouchPhase.Moved || touch2.phase == TouchPhase.Moved) ｛ Vector2 curVec = touch2.position - touch1.position; Vector2 oldVec = oldTouch2.position - oldTouch1.position; float angle = Vector2.Angle(oldVec, curVec); angle *= Mathf.Sign(Vector3.Cross(oldVec, curVec).z); transform.Rotate(new Vector3(0, 0, angle)); oldTouch1 = touch1; oldTouch2 = touch2; ｝ ｝ ｝
另一种写法，参考的博客已失效，这里贴一下
const float pinchTurnRatio = Mathf.PI / 2;
//用这个数值来判定旋转的最小角度，自己决定大小
const float minTurnAngle = 0;
/// <summary>
/// The delta of the angle between two touch points
/// </summary>
static public float turnAngleDelta;
/// <summary>
/// The angle between two touch points
/// </summary>
static public float turnAngle;
/// <summary>
/// Calculates Pinch and Turn - This should be used inside LateUpdate
/// </summary>
static public void Calculate()
｛
//pinchDistance = pinchDistanceDelta = 0;
turnAngle = turnAngleDelta = 0;
// if two fingers are touching the screen at the same time ...
if (Input.touchCount == 2) ｛
Touch touch1 = Input.touches[0];
Touch touch2 = Input.touches[1];
// ... if at least one of them moved ...如果有一根手指有移动
if (touch1.phase == TouchPhase.Moved || touch2.phase == TouchPhase.Moved) ｛
// ... or check the delta angle between them ...
//当前两手指与X轴的角
turnAngle = Angle(touch1.position, touch2.position);
//之前两手指与X的角度
float prevTurn = Angle(touch1.position - touch1.deltaPosition,
touch2.position - touch2.deltaPosition);
//旋转的偏移量， 增量角
turnAngleDelta = Mathf.DeltaAngle(prevTurn, turnAngle);
// ... if it's greater than a minimum threshold, it's a turn!
//增量角如果大于设定值
if (Mathf.Abs(turnAngleDelta) > minTurnAngle) ｛
turnAngleDelta *= pinchTurnRatio;
｝ else ｛
turnAngle = turnAngleDelta = 0;
｝
｝
｝
//鼠标判断事件，这个只是个测试
#if UNITY_EDITOR
MouseRotateEvent();
#endif
｝
/// <summary>
/// 取两个向量之间的角度 与X轴
/// </summary>
/// <param name="pos1"></param>
/// <param name="pos2"></param>
/// <returns></returns>
static private float Angle(Vector2 pos1, Vector2 pos2)
｛
//取两个向量相减
Vector2 from = pos2 - pos1;
//X轴
Vector2 to = new Vector2(1, 0);
//与X轴夹角
float result = Vector2.Angle(from, to);
//向量的叉乘
Vector3 cross = Vector3.Cross(from, to);
//如果超出360度
if (cross.z > 0) ｛
//用360来减这个角度
result = 360f - result;
｝
return result;
｝
#if UNITY_EDITOR
static bool isPress = false;
static float preAngle = 0;
/// <summary>
/// 鼠标右键旋转事件，并非完美实现，因为没有判断角度为正还是为负。
/// </summary>
static public void MouseRotateEvent()
｛
if (Input.GetMouseButton(1)) ｛
//第一次按下
if (!isPress) ｛
//上一帧的角度
preAngle = Angle(Input.mousePosition, Vector2.zero);
isPress = true;
｝ else ｛
//转动的角度
turnAngle = Angle(Input.mousePosition, Vector2.zero);
//旋转的偏移量， 增量角
turnAngleDelta = Mathf.DeltaAngle(preAngle, turnAngle);
Log.log("增量角："+turnAngleDelta);
//增量角如果大于设定值
if (Mathf.Abs(turnAngleDelta) > minTurnAngle) ｛
turnAngleDelta *= pinchTurnRatio;
｝ else ｛
turnAngle = turnAngleDelta = 0;
｝
//更新为这一帧
preAngle = Angle(Input.mousePosition, Vector2.zero);
｝
｝ else ｛
isPress = false;
｝
｝
#endif
/// <summary>
/// 绕点旋转，或者是Z轴旋转？
/// </summary>
public bool isRotateAround = false;
//目标
public Transform target;
//围绕点
protected Vector3 axis ｛
get ｛
return new Vector3(target.position.x, transform.position.y, target.position.z);
｝
｝
//void Start()
//｛
// if (target == null) ｛
// Debug.Log("target is null!");
// enabled = false;
// ｝
//｝
void Update()
｛
Calculate();
if (Mathf.Abs(turnAngleDelta) > 0) ｛
if (isRotateAround) ｛
//围点旋转
transform.RotateAround(axis, Vector3.up, -turnAngleDelta);
//目视对方
transform.LookAt(target);
｝ else ｛
Quaternion desiredRotation = transform.rotation;
Vector3 rotationDeg = Vector3.zero;
//z轴旋转
rotationDeg.z = -turnAngleDelta;
desiredRotation *= Quaternion.Euler(rotationDeg);
transform.rotation = desiredRotation;
｝
｝
｝
来自：https://blog.csdn.net/ys5773477/article/details/54986021