Unity3D鼠标滚轮控制摄像机远近

	//  鼠标中间键
	var MouseWheelSensitivity = 5;
	var MouseZoomMin = 2;
	var MouseZoomMax = 10;

   摄像机距离视角中心最近为2,最远为10,鼠标灵敏度为5

	// 如果按住滑轮
		if (Input.GetAxis("Mouse ScrollWheel") != 0)
	 {
		
		//Debug.Log(Input.GetAxis("Mouse ScrollWheel"));
		//Debug.Log(distance);
		if (normalDistance >= MouseZoomMin && normalDistance <= MouseZoomMax)
		{
			normalDistance -= Input.GetAxis("Mouse ScrollWheel") * MouseWheelSensitivity;
		}
		
		if (normalDistance < MouseZoomMin)
		{
			normalDistance = MouseZoomMin;
		}
		if (normalDistance > MouseZoomMax)
		{
			normalDistance = MouseZoomMax;
		}
	}