Unity双指旋转

发表于2018-09-16
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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

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