做了一个水果忍者的游戏，但是射线physics.raycast返回值总是为假

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Mouse : MonoBehaviour
{
public GameObject ballHalf;
public GameObject cubeHalf;
public GameObject coneTopHalf;
public GameObject coneHalf;
GameObject Obj = null;

// Start is called before the first frame update
void Start()
{

}

Ray GenerateMouseRay(Vector3 touchPos)
{
    Vector3 mousePosFar = new Vector3(touchPos.x, touchPos.y, Camera.main.farClipPlane);
    Vector3 mousePosNear = new Vector3(touchPos.x, touchPos.y, Camera.main.farClipPlane);
    Vector3 mousePosF = Camera.main.ScreenToViewportPoint(mousePosFar);
    Vector3 mousePosN = Camera.main.ScreenToViewportPoint(mousePosNear);
    Ray mr = new Ray(mousePosN, mousePosF - mousePosN);
    return mr;
}

// Update is called once per frame
void Update()
{
    if (((Input.touchCount>0 && Input.GetTouch(0).phase == TouchPhase.Moved) || Input.GetMouseButton(0)))
    {
        Plane objPlane = new Plane(Camera.main.transform.forward * -1, this.transform.position);
        Ray mRay = Camera.main.ScreenPointToRay(Input.mousePosition);
        float rayDistance;
        if(objPlane.Raycast(mRay,out rayDistance))
        {
            this.transform.position = mRay.GetPoint(rayDistance);
        }

        Ray mouseRay = GenerateMouseRay(Input.mousePosition);
        RaycastHit hit;
        if (Physics.Raycast(mouseRay.origin,mouseRay.direction,out hit))
        {
            bool a = Physics.Raycast(mouseRay.origin, mouseRay.direction, out hit);

            Obj = hit.transform.gameObject;
            Debug.Log(hit.transform.tag);
            if (Obj.tag == "ball")
            {
                GameObject a1 = (GameObject)Instantiate(ballHalf, Obj.transform.localPosition, Obj.transform.localRotation);
                a1.transform.rotation *= Quaternion.Euler(0,0,90);
                a1.transform.Translate(3f, 0, 0);
                a1.GetComponent<Rigidbody>().velocity = Obj.GetComponent<Rigidbody>().velocity;
                GameObject a2 = (GameObject)Instantiate(ballHalf, Obj.transform.localPosition, Obj.transform.localRotation);
                a2.transform.rotation *= Quaternion.Euler(0, 0, -90);
                a2.GetComponent<Rigidbody>().velocity = Obj.GetComponent<Rigidbody>().velocity;
                Destroy(Obj);
            }
        }

    }
}

}

里面的刚体，碰撞器都有安装