Problems with ScreenToWorldPoint in 2D game

Question

I'm new to unity, I have a problem with my prefabs Instantiating off camera screen, I am using WorldToScreenPoint but when I run the game objects are half on and off screen view.

Also when I view game in scene view, while the game is running object spawn outside the camera view.

Can any take a look at my code and point me in the right direction

cheers

     var prefab : GameObject;
      
     function Start() {
        while (true) {
        var limitMin:Vector3 = Camera.main.ScreenToWorldPoint(Vector3(0, 0, Camera.main.transform.position.y));
        var limitMax:Vector3 = Camera.main.ScreenToWorldPoint(Vector3(Screen.width, Screen.height, Camera.main.transform.position.y));
       
           var spawnPos: Vector3 = Vector3(Random.Range(limitMin.x, limitMax.x), Random.Range(limitMin.y, limitMax.y));
           Instantiate(prefab, spawnPos, Quaternion.identity);
           yield WaitForSeconds (3);
        }
     }

Answer 1

Answer by slek120 · Mar 17, 2014 at 10:42 AM

The position of a transform is the center of that game object. You need to add half of the size to the range. Half of the size is given by bounds.extents.

 var padding:Vector3 = prefab.renderer.bounds.extents;
 var spawnPos: Vector3 = Vector3(Random.Range(limitMin.x + padding.x, limitMax.x - padding.x),
                                 Random.Range(limitMin.y + padding.y, limitMax.y - padding.y));

Add comment · Show 8 · Share

fuzzywig · Mar 17, 2014 at 10:59 AM 0

Share

Thanks for helping, but they still spawn outside camera view, half on screen half off, I have included the code you posted.

Have i missed something

 var prefab : GameObject;
      
     function Start() {
            while (true) {
                  var limit$$anonymous$$in:Vector3 = Camera.main.ScreenToWorldPoint(Vector3(0, 0, Camera.main.transform.position.y));
                  var limit$$anonymous$$ax:Vector3 = Camera.main.ScreenToWorldPoint(Vector3(Screen.width, Screen.height, Camera.main.transform.position.y));
                  var padding:Vector3 = prefab.renderer.bounds.extents;
                  var spawnPos: Vector3 = Vector3(Random.Range(limit$$anonymous$$in.x + padding.x, limit$$anonymous$$ax.x - padding.x), Random.Range(limit$$anonymous$$in.y + padding.y, limit$$anonymous$$ax.y - padding.y));
                   //var spawnPos: Vector3 = Vector3(Random.Range(limit$$anonymous$$in.x, limit$$anonymous$$ax.x), Random.Range(limit$$anonymous$$in.y, limit$$anonymous$$ax.y));
                   Instantiate(prefab, spawnPos, Quaternion.identity);
                   yield WaitForSeconds (3);
            }
     }

slek120 · Mar 17, 2014 at 11:35 AM 0

Share

Is your camera in perspective? The distance from the camera in the z-axis matters then.

I was going to mention that you use Camera.main.transform.position.y in ScreenToWorldPoint. I'm not sure but you might want to use -Camera.main.transform.position.z.

slek120 · Mar 17, 2014 at 11:44 AM 0

Share

or you can do

 ScreenToWorldPoint( .., .., distanceFromCamera);
 spawnPos:Vector3 = Vector3( .., .., limit$$anonymous$$in.z);

But it looks pretty weird when you have a rotated camera. I don't know the answer to your question if you do that.

fuzzywig · Mar 17, 2014 at 11:50 AM 0

Share

No the camera is in orthographic I think, take a look at the image i have included.

Also I have tried the -Camera.main.transform.position.z, same results

[1]: /storage/temp/23714-unity+2d+camera+setup.png

unity 2d camera setup.png (37.5 kB)

slek120 · Mar 17, 2014 at 11:59 AM 0

Share

That is odd. I basically copied your code and it works.

 #pragma strict
 
 var prefab : GameObject;
  
 function Start() {
        while (true) {
             var limit$$anonymous$$in: Vector3 = Camera.main.ScreenToWorldPoint(Vector3(0, 0, -Camera.main.transform.position.z));
             var limit$$anonymous$$ax: Vector3 = Camera.main.ScreenToWorldPoint(Vector3(Screen.width, Screen.height, -Camera.main.transform.position.z));
             var padding: Vector3 = prefab.renderer.bounds.extents;
             var spawnPos: Vector3 = Vector3(Random.Range(limit$$anonymous$$in.x + padding.x, limit$$anonymous$$ax.x - padding.x), Random.Range(limit$$anonymous$$in.y + padding.y, limit$$anonymous$$ax.y - padding.y));
             //var spawnPos: Vector3 = Vector3(Random.Range(limit$$anonymous$$in.x, limit$$anonymous$$ax.x), Random.Range(limit$$anonymous$$in.y, limit$$anonymous$$ax.y));
             Instantiate(prefab, spawnPos, Quaternion.identity);
             yield WaitForSeconds (3);
        }
 }

Show more comments

Problems with ScreenToWorldPoint in 2D game

1 Reply

Your answer

Follow this Question

Related Questions