C# 将对象提升到位，并在另一个轴上跟随鼠标

所以我试着让一个刚体提升到一个设定的高度，然后用鼠标在另一个轴上移动

    private void levitateObject()
{
    Ray playerAim = playerCamera.GetComponent<Camera>().ViewportPointToRay(new Vector3(0.5f, 0.5f, 0));
    /*Finds the next position for the object held to move to, depending on the Camera's position
    ,direction, and distance the object is held between you two.*/
    Vector3 nextPos = playerCamera.transform.position + playerAim.direction * 5;
    //Takes the current position of the object held
    Vector3 currPos = levitatingObject.transform.position;

    levitatingObject.GetComponent<Rigidbody>().velocity = (nextPos - currPos)*10 ;

}

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有什么问题吗？现在我想和5号摄像机保持一定的距离，但我想保持不变。