Unity implements the mouse to drag 3D objects

using ;
using ;
using UnityEngine;

public class ModelDrages : MonoBehaviour 
{

//The camera that emits raysprivate Camera cam;
// Objects that collide with raysprivate GameObject go;
//The name of the object that the ray collidespublic static string btnName;
private Vector3 screenSpace;
private Vector3 offset;
private bool isDrage = false;

// Use this for initialization
void Start ()
{
 cam = ;
}

// Update is called once per frame
 void Update ()
{
 //Overall initial position Ray ray = ();
 //Rays emitted from the camera to click coordinates RaycastHit hitInfo;
 if (isDrage == false)
 {
  if(Physics .Raycast (ray,out hitInfo))
  {
   //Shadow the rays and can only be seen in Scene view   (, );
   go = ;
   print(btnName);
   screenSpace = ();
   offset =  - (new Vector3(, , ));
   //The name of the object   btnName = ;
   //The name of the component  }
  else
  {
   btnName = null;
  }
 }
 if((0))
 {
  Vector3 currentScreenSpace = new Vector3(, , );
  Vector3 currentPosition = (currentScreenSpace) + offset;
  if (btnName != null)
  {
    = currentPosition;
  }
  isDrage = true;
 }
 else
 {
  isDrage = false;
 }
 }

}