NullReferenceException: Object reference... when trying to instantiate an object

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I'm trying to get an object to instantiate upon click. When I try to test out my script i get

NullReferenceException: Object reference not set to an instance of an object

blockSpawn.Update () (at Assets/scripts/blockSpawn.js:10) as an error. I've been trying to fix this for around 5 hours now with no luck.. I'm new to this so I may be missing something simple. I appreciate any help with this issue. var block : GameObject;
function Start(){ }
function Update () {
var mousex = Input.mousePosition.x; var mousey = Input.mousePosition.y; var ray = Camera.main.ScreenPointToRay (Vector3(mousex,mousey,0));
var hit : RaycastHit;
if (Physics.Raycast (ray, hit, 200)) {
} if ( Input.GetMouseButtonDown(0) ) { var createBlock = Instantiate(block, hit.point, Quaternion.identity);
} else {}

} Thanks again for the help guys!

Answer 1

Best Answer

Answer by NoseKills · Jun 03, 2014 at 05:46 AM

The hit in your code can be null. The if (Physics.Raycast (ray, hit, 200)) check is there so that you'd only do stuff if the raycast hits something, but you have left the of clause empty and try to do stuff upon mouse click even when the ray doesn't hit anything.

If you only want to do stuff when the mouse is clicked, then that should be your first condition.

     if ( Input.GetMouseButtonDown(0) )
        {
         var hit : RaycastHit;
         if (Physics.Raycast (ray, hit, 200)) 
         {
             var createBlock = Instantiate(block, hit.point, Quaternion.identity);  
         }
        }

P.S. If you just want to create an object on the screen where the player clicked/touched, you don't need to raycast. Your code checks whether the click hits another object (with a collider) on the screen and tries to create a new object where the click hits the pre-existing object.

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gulpy3 · Jun 03, 2014 at 01:11 PM 0

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Thanks for the help man. Got it working! I was wondering if you would be willing to help with one more problem. I want it to spawn a block depending on the value of a random number. So far when I try the code below.. it only spawns block 1 even though it is generating numbers up to 20.

     var block1 : Rigidbody2D;
     var block2 : Rigidbody2D;
     
     function Update()
     {
     
     if (Input.Get$$anonymous$$ouseButtonDown(0))
     {
     var rand = Random.Range(1.0, 20.0);
     }
     if (Input.Get$$anonymous$$ouseButtonDown(0 && (rand < 10.0)))
     {
         var clone = Instantiate(block1, transform.position, transform.rotation);
         clone.velocity = transform.TransformDirection(Vector3(0, 0, 0));
         Debug.Log(rand);
     }
     else if (Input.Get$$anonymous$$ouseButtonDown(0 && (rand > 10.0)))
      {
     var clone2 = Instantiate(block2, transform.position, transform.rotation);
         clone2.velocity = transform.TransformDirection(Vector3(0, 0, 0));
      Debug.Log(rand);
     }
 
     }

gulpy3 · Jun 03, 2014 at 01:16 PM 0

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Ignore the question above, I fixed it! Thanks anyway!

NullReferenceException: Object reference... when trying to instantiate an object

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