Accessing start () function from another script error ?

Question

How can i access start() function from another script since start function can be only defined once

This is the script containing start() -

using UnityEngine;
 using System.Collections;

public class MoverBolt : MonoBehaviour {
public PlayerControl obj ; 
public float speed ;
public Rigidbody rb;

  void Start(){
    rb = GetComponent<Rigidbody>();
    rb.velocity = transform.forward * speed;

 }
}

Script which need to access start()

using UnityEngine;
using System.Collections;
  [System.Serializable]
 public class Boundary{
public float xMax,xMin,zMax,zMin;
}
  public class PlayerControl : MonoBehaviour
 { 
  public Boundary boundary ; 
  public float velocity;
   public float tilt;
    MoverBolt obj = new MoverBolt();  
 /* I made an object but it seems you are not supposed to create an object of class which is inheritance of MonoBehaviour */

    void FixedUpdate()
{
    float moveHorizontal = Input.GetAxis ("Horizontal");
    float moveVertical = Input.GetAxis ("Vertical");
    Vector3 movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);
    obj.rb.velocity = movement*velocity;
    Vector3 current_position = obj.rb.position;
    obj.rb.position = new Vector3 ( Mathf.Clamp(current_position.x,boundary.xMin,boundary.xMax),
                                       0.0f,
                               Mathf.Clamp(current_position.z, boundary.zMin, boundary.zMax)
                                       );
    obj.rb.rotation= Quaternion.Euler(0.0f,0.0f,obj.rb.velocity.x*-tilt );
   }

 }

Error You are trying to create a MonoBehaviour using the 'new' keyword. This is not allowed. MonoBehaviours can only be added using AddComponent().

Are there any alternatives ?

Well you shouldn't be treating MonoBehaviour-derived classes as regular classes and trying to instantiate them via new. Instead you add the scripts as components and add them to a Unity object in the editor. Besides, Start() is private — user585968
– user585968, Commented Aug 8, 2015 at 6:12
I added script as components. how can i access start() from another component's script ?? — NinjaCoder
– NinjaCoder, Commented Aug 8, 2015 at 6:15
You can't. 1) it's private 2) It's called only once by Unity 3) You shouldn't make assumptions on call order — user585968
– user585968, Commented Aug 8, 2015 at 6:19

JeanLuc · Accepted Answer · 2015-08-09 07:40:10Z

1

it's possible to call a Start() method from outside. just make it public.

public class MoverBolt : MonoBehaviour {
    public void Start () 
    {
        Debug.Log("MoverBolt.Start() was called");
    }
}

public class PlayerControl : MonoBehaviour {
    [SerializeField]
    private MoverBolt _moverBolt;

    void Start () 
    {
        _moverBolt.Start();
    }
}

The output in the console of this is

MoverBolt.Start() was called
MoverBolt.Start() was called

UPDATE 1

I would not recommend this, because the Start() method is called by your code and the game engine again.

When I need to make sure a MonoBehaviour is properly setup, before another class uses it. I replace the Awake/Start method with public void Initialize() method and call that from outside.

edited Aug 9, 2015 at 7:40

answered Aug 8, 2015 at 23:21

JeanLuc

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1 Comment

NinjaCoder Over a year ago

I thought it was a bad programming practice to make start() public

Neeraj Kumar · Accepted Answer · 2015-08-08 06:19:39Z

0

Very simple answer. You can't Access start () function from any other scripts.

answered Aug 8, 2015 at 6:19

Neeraj Kumar

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Comments

LVBen · Accepted Answer · 2015-08-09 02:26:39Z

0

Use "Instantiate". For example, you can create of prefab of the game object that you want to make a copy of and then use the prefab to generate the new objects.

public class ObjectFactory : MonoBehaviour()
{
   public GameObject prefab;  // Set this through the editor.

   public void GenerateObject()
   {
      // This will create a copy of the "prefab" object and its Start method will get called:
      Instantiate(prefab);
   }
}

answered Aug 9, 2015 at 2:26

LVBen

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3 Comments

NinjaCoder Over a year ago

I made the prefab of the bolt but as soon as i enable the space ship the compiler shows error .If there is a start() in MoverBolt how can the PlayerControl can access rigidbody object (rb) so that all functions under it works ie ( rb.velocity,rb.position ect )

LVBen Over a year ago

Put the initialization code in Awake instead of Start.

NinjaCoder Over a year ago

It worked but when i enter play mode at first i can move the Spaceship but after dragging and dropping bolt prefab into the editor the Spaceship freezes :(

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