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Problem with instantiating Projectile

Discussion in 'Scripting' started by Ricks, Jan 16, 2012.

  1. Ricks

    Ricks

    Joined:
    Jun 17, 2010
    Messages:
    647
    Hello all,
    I got a problem which I cannot seem to solve and I don't know why. In my script I try instantiate an arrow as follows:

    PHP:
    Vector3 arrowLookPos target.position-transform.position;
            
    Quaternion arrowLookRotation Quaternion.LookRotation(arrowLookPos);        
            
    Rigidbody clone = (RigidbodyInstantiate(arrowtransform.positionarrowLookRotation);
            clone.
    velocity = clone.transform.forward 30;
            
    Physics.IgnoreCollision(clone.collidertransform.root.collider);
    This code works correctly as long as I make a "public Rigidbody arrow" and Drag&Drop my Prefab (with the name "Arrow") into the specific slot. However if I try to instantiate using "Resources.Load("Arrow") I get an Exception like "Object Reference is not set to an instance of an object". This is the code I used:

    PHP:
    GameObject arrow = (GameObjectResources.Load("Arrow");
            
            
    Rigidbody clone = Instantiate(arrowtransform.positionarrowLookRotation) as Rigidbody;
            clone.
    velocity = clone.transform.forward 30;
    The compiler shows me the error in the last line (the one with clone.velocity). Therefore my question is: how can I instantiate rigidbody projectiles correctly?
     
    Last edited: Jan 16, 2012
  2. JamesLeeNZ

    JamesLeeNZ

    Joined:
    Nov 15, 2011
    Messages:
    4,388
    Since ive never used resources.load, this is a bit of a guess, but if its not in the correct path, it wont load.

    Assets/Resources/[prefab name]
     
  3. Ricks

    Ricks

    Joined:
    Jun 17, 2010
    Messages:
    647
    Thanks for the answer, but I got the path right. I have it in the "Resources" folder. Also I have another prefab in this folder which I instantiate (a plain gameobject, not a rigidbody) which loads correctly everytime without error. I really don't get where the error is with this rigidbody projectile...
     
  4. JamesLeeNZ

    JamesLeeNZ

    Joined:
    Nov 15, 2011
    Messages:
    4,388
    why dont you just instantiate the gameobject then access the rigidbody?


    GameObject instance = Instantiate(Resources.Load("enemy", typeof(GameObject)));
    instance.rigidBody.velocity....
     
  5. avidesk

    avidesk

    Joined:
    Sep 12, 2011
    Messages:
    62
    Similar to what jlcnz is saying...

    If I understand correctly you should be instantiating a gameObject and modifying the gameObject's transform. I thought Rigidbody is simply a component that needs to have a gameObject as a parent? A rigidbody by itself doesn't technically have a transform component, hence the null reference exception.

    This is just my first thought, I could be totally wrong.
     
  6. Ricks

    Ricks

    Joined:
    Jun 17, 2010
    Messages:
    647
    Thanks again for this hint, I have already tried that, and it works on the first view - until I saw that:
    Every instance spawns at first for a very short time on (0,0,0) in the scene and only afterwards you can set the correct location. So if you spawn multiple instances you see lots of flickering disappering/appearing arrows in the scenery before the arrows are actually set to their specific location :-|

    Unfortunately there is no function which allows me to do that: Rigidbody = Instantiate(Resources.Load("enemy", typeof(GameObject),position,rotation). I mean, do I really need to uplift the whole scenery to have (0,0,0) out of sight? There should be another clean solution, ain't it? :-(
     
  7. JamesLeeNZ

    JamesLeeNZ

    Joined:
    Nov 15, 2011
    Messages:
    4,388
    Code (csharp):
    1.  
    2. GameObject projectile = Instantiate(Resources.Load("arrow", typeof(GameObject)), location, rotation);
    3.  
    4. projectile.rigidBody....
    5.  
    6.  
    if if doesnt like that, try
    GameObject projectile = Instantiate((GameObject)Resources.Load("arrow", typeof(GameObject)), location, rotation);
     
  8. Ricks

    Ricks

    Joined:
    Jun 17, 2010
    Messages:
    647
    THANKS a million! This was it! It works!

    (I always tried to instantiate it with "Rigidbody clone = ...Instantiate/Resources.Load etc." or to cast the GameObject to a "Rigidbody" which resulted in errors. Obviously I have understood this variable "Rigidbody" wrong. I only need to instantiate the GameObject and then access its rigidbody component).
     
    Last edited: Jan 16, 2012