垂直于任意平面的拖动

毕竟重要的是VerticalPlane这个平面，你可以直接在Unity中创建一个Quad。然后拉到这个代码里面。
VerticalPlane.transform.up的方向，就是垂直你拖动平面的方向。所以你可以调整你VerticalPlane的角度，可以比较直观的获得你所需要垂直拖动的平面。代码应该看看都能懂，比较简单。

  public class DragStuffBase : MonoBehaviour, IBeginDragHandler, IDragHandler, IEndDragHandler
        {

            public Camera MainCamera;
            private float depthZ;
            public Vector3 InitPos;
            public bool isCanDrag = false;
            public float DepthZLerp = -0.3f;
            private bool drag;

            public Transform VerticalPlane;//垂直滑动的平面



            float VerticalLineLength;
            float distance;

            Vector3 originPointPos;
            Vector3 originObjPos;

            public Vector3 LerpPos=new Vector3(0,0.2f,0);//

            public void Init()
            {
               
                
            }
            // Use this for initialization
            void Start()
            {
              

            }

            // Update is called once per frame
            void Update()
            {

            }

            public void OnBeginDrag(PointerEventData eventData)
            {
                if (DOTween.IsTweening(this.transform))
                    return;
                if (isCanDrag)
                {
                    depthZ = this.MainCamera.WorldToScreenPoint(this.transform.position).z;
                    InitPos = this.transform.position;
                    drag = true;

                    distance = eventData.pointerPressRaycast.distance; ;
                    VerticalLineLength = GetVerticalLine(eventData.position, distance);
                    originPointPos = GetWorldPos(eventData.position, distance);
                    originObjPos = this.gameObject.transform.position+ LerpPos;
                    OnBeginDragEvent(eventData);
                }
            }

            public void OnDrag(PointerEventData eventData)
            {
                if (!drag)
                    return;

                // this.transform.position = MainCamera.ScreenToWorldPoint(new Vector3(eventData.position.x, eventData.position.y, depthZ + DepthZLerp));

                Vector3 tempPos = GetWorldPos(eventData.position, GetDragDistance(eventData.position));
                Vector3 deltaPos = tempPos - originPointPos;
                // this.transform.position = (originObjPos + deltaPos);

                this.transform.position = tempPos + LerpPos;

                OnDragEvent(eventData);
            }

            public void OnEndDrag(PointerEventData eventData)
            {
                if (!drag)
                    return;
                drag = false;
                OnEndDragEvent(eventData);
            }

            public virtual void OnBeginDragEvent(PointerEventData eventData)
            {

            }

            public virtual void OnDragEvent(PointerEventData eventData)
            {

            }

            public virtual void OnEndDragEvent(PointerEventData eventData)
            {

            }


            float GetVerticalLine(Vector2 mousePos, float distance)
            {
                Ray objRay = MainCamera.ScreenPointToRay(mousePos);
                Ray vertical = new Ray(MainCamera.transform.position, new Vector3(VerticalPlane.transform.up.x, VerticalPlane.transform.up.y, VerticalPlane.transform.up.z));
                Vector3 objDir = objRay.direction;
                Vector3 verticalLineDir = vertical.direction;

                float angle = Vector3.Angle(objDir, verticalLineDir);

                return distance * Mathf.Cos(angle * Mathf.Deg2Rad);
            }

            float GetDragDistance(Vector2 mousePos)
            {
                Ray vertical = new Ray(MainCamera.transform.position, new Vector3(VerticalPlane.transform.up.x, VerticalPlane.transform.up.y, VerticalPlane.transform.up.z));
                Ray objRay = MainCamera.ScreenPointToRay(mousePos);

                Vector3 objDir = objRay.direction;
                Vector3 verticalLineDir = vertical.direction;

                float angle = Vector3.Angle(objDir, verticalLineDir);

                return VerticalLineLength / Mathf.Cos(angle * Mathf.Deg2Rad);
            }

            protected Vector3 GetWorldPos(Vector2 mousePos, float distance)
            {
                Ray ray = MainCamera.ScreenPointToRay(mousePos);
                return ray.GetPoint(distance);
            }

        }
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