AR 如何在扫描到AR图标之后进行场景（摄像头）漫游

工具：
Unity, Vuforia

 

首先采用上篇博文中的方案二来实现AR的Extanded Tracking。

同时，使用一个空GameObject（命名为AR Objects）来与ImageTarget的transform进行同步。使用AR Objects的child（命名为AR Children）作为漫游中需要执行移动的对象。

在AR Children中挂载两个脚本：MoveAgainstCam.cs和PinchZoom.cs。

MoveAgainstCam.cs用来移动AR Children，模拟漫游效果。PinchZoom.cs用来处理手指输入，放大操作类似于向前移动，缩小操作类似于后退。（效果类似于“放大”和“缩小”）

代码如下：

MoveAgainsCam.cs

namespace Will
{
    public class MoveAgainstCam : MonoBehaviour
    {

        public GameObject m_Camera;

        public float m_MoveSpeed = 1.0f;

        private Transform m_CamTrans;

        //--------------------- Life Cycle -----------------------//

        private void Awake()
        {
            m_CamTrans = m_Camera.transform;
        }

        
         //--------------------- Interface -----------------------//

        public void MoveForward(float fraction)
        {
            if(fraction == 0)
            {
                fraction = 1;
            }
            transform.position -= m_CamTrans.forward * m_MoveSpeed * fraction;
  
        }
    }

}

PinchZoom.cs：

namespace Will
{
    public class PinchZoom : MonoBehaviour
    {

        public float ZoomSpeed = 0.01f;        // The rate of change of the field of view in perspective mode.
        public float RotateSpeed = 30.0f;

        private MoveAgainstCam m_MoveAgainstCamScript;

        private void Awake()
        {
            m_MoveAgainstCamScript = GetComponent();
        }

        void Update()
        {

            // If there are two touches on the device...
            if (Input.touchCount == 2)
            {
                // Store both touches.
                Touch touchZero = Input.GetTouch(0);
                Touch touchOne = Input.GetTouch(1);

                /*------------------------ Zoom --------------------------*/

                // Find the position in the previous frame of each touch.
                Vector2 touchZeroPrevPos = touchZero.position - touchZero.deltaPosition;
                Vector2 touchOnePrevPos = touchOne.position - touchOne.deltaPosition;

                // Find the magnitude of the vector (the distance) between the touches in each frame.
                float prevTouchDeltaMag = (touchZeroPrevPos - touchOnePrevPos).magnitude;
                float touchDeltaMag = (touchZero.position - touchOne.position).magnitude;

                // Find the difference in the distances between each frame.
                float deltaMagnitudeDiff = prevTouchDeltaMag - touchDeltaMag;

                // Move 
                m_MoveAgainstCamScript.MoveForward(-deltaMagnitudeDiff); 

            }
        }
    }
}