DragRigidbody Distance <= error

Heya, Unity have this free script, But want i am having trouble with is, You can click on the block from any where around the map, I don't want this, I want it so "Player" as to find how to get it first then able to click and drag, I've messed around with the vaules in the code but no luck,

The code i'm trying to add it:
if(distance <= 30){
//drag rigidbody
}

but having errors bad


If you can help be great code below
thank you.

Code (CSharp):

1. using System;
2. using System.Collections;
3. using UnityEngine;
4.  
5. namespace UnityStandardAssets.Utility
6. {
7.     public class DragRigidbody : MonoBehaviour
8.     {
9.         const float k_Spring = 50.0f;
10.         const float k_Damper = 5.0f;
11.         const float k_Drag = 10.0f;
12.         const float k_AngularDrag = 5.0f;
13.         const float k_Distance = 0.2f;
14.         const bool k_AttachToCenterOfMass = false;
15.  
16.         private SpringJoint m_SpringJoint;
17.  
18.  
19.         private void Update()
20.         {
21.             // Make sure the user pressed the mouse down
22.             if (!Input.GetMouseButtonDown(0))
23.             {
24.                 return;
25.             }
26.  
27.             var mainCamera = FindCamera();
28.  
29.             // We need to actually hit an object
30.             RaycastHit hit = new RaycastHit();
31.             if (
32.                 !Physics.Raycast(mainCamera.ScreenPointToRay(Input.mousePosition).origin,
33.                                  mainCamera.ScreenPointToRay(Input.mousePosition).direction, out hit, 100,
34.                                  Physics.DefaultRaycastLayers))
35.             {
36.                 return;
37.             }
38.             // We need to hit a rigidbody that is not kinematic
39.             if (!hit.rigidbody || hit.rigidbody.isKinematic)
40.             {
41.                 return;
42.             }
43.  
44.             if (!m_SpringJoint)
45.             {
46.                 var go = new GameObject("Rigidbody dragger");
47.                 Rigidbody body = go.AddComponent<Rigidbody>();
48.                 m_SpringJoint = go.AddComponent<SpringJoint>();
49.                 body.isKinematic = true;
50.             }
51.  
52.             m_SpringJoint.transform.position = hit.point;
53.             m_SpringJoint.anchor = Vector3.zero;
54.  
55.             m_SpringJoint.spring = k_Spring;
56.             m_SpringJoint.damper = k_Damper;
57.             m_SpringJoint.maxDistance = k_Distance;
58.             m_SpringJoint.connectedBody = hit.rigidbody;
59.  
60.             StartCoroutine("DragObject", hit.distance);
61.         }
62.  
63.  
64.         private IEnumerator DragObject(float distance)
65.         {
66.             var oldDrag = m_SpringJoint.connectedBody.drag;
67.             var oldAngularDrag = m_SpringJoint.connectedBody.angularDrag;
68.             m_SpringJoint.connectedBody.drag = k_Drag;
69.             m_SpringJoint.connectedBody.angularDrag = k_AngularDrag;
70.             var mainCamera = FindCamera();
71.             while (Input.GetMouseButton(0))
72.             {
73.                 var ray = mainCamera.ScreenPointToRay(Input.mousePosition);
74.                 m_SpringJoint.transform.position = ray.GetPoint(distance);
75.                 yield return null;
76.             }
77.             if (m_SpringJoint.connectedBody)
78.             {
79.                 m_SpringJoint.connectedBody.drag = oldDrag;
80.                 m_SpringJoint.connectedBody.angularDrag = oldAngularDrag;
81.                 m_SpringJoint.connectedBody = null;
82.             }
83.         }
84.  
85.  
86.         private Camera FindCamera()
87.         {
88.             if (GetComponent<Camera>())
89.             {
90.                 return GetComponent<Camera>();
91.             }
92.  
93.             return Camera.main;
94.         }
95.     }
96. }
97.  

 

Anyone able to help?

 

On line #33 change the 100 to your desired ray length.