Unity: Transforms vs GameObjects

Tachyon

Hey, so my cube puzzle replica is coming along and I am stuck again in some code. A friend helped code some logic to iterate through game objects in an empty container object so that cubes would not occupy the same space:

private function handleButtonClick(columnIncrementer:int, rowIncrementer:int)
{
	for (var child:Transform in container.transform) 
    {
    	
    	var currentColumn:int = Mathf.Floor(child.position.z / cellSize);
    	var currentRow:int = Mathf.Floor(child.position.x / cellSize);
    	
    	var openColumnIndex:int = currentColumn + columnIncrementer;
    	var openRowIndex:int = currentRow + rowIncrementer;
    	
    	while (checkIfBlockOccupied(openColumnIndex, openRowIndex) == true && openColumnIndex > -1 && openRowIndex > -1 && openColumnIndex < columns && openRowIndex < rows)
    	{
    		openColumnIndex += columnIncrementer;
    		openRowIndex += rowIncrementer;
    	}
    	
    	if (openColumnIndex > -1 && openRowIndex > -1 && openColumnIndex < columns && openRowIndex < rows)
    	{
    		setBlockPosition(child, currentColumn + columnIncrementer, currentRow + rowIncrementer);
       ....

My understanding from this code is that game objects are stored in the transform of the container object?

Now when I call the setBlockPosition function..

private function setBlockPosition(child:Transform, column:int, row:int) : void 
{	
	iTween.MoveTo(child, Vector3(row * cellSize, 0, column * cellSize), 2); 
	//child.position.z = column * cellSize;
	//child.position.x = row * cellSize;
}

..I receive an error because the iTween MoveTo function requires game object information instead transform information. I hope this is making sense? Can I convert a transform into a game object? Thoughts?

Elyaradine

Just use child.gameObject. :)

You can refer to a GameObject's transforms by calling MyGameObject.transform, and you can refer to a Transform's gameobject by calling MyTransform.gameObject. You could do that endlessly if... well... you wouldn't, but you could. :P (i.e. MyGameObject.transform.gameObject.transform.gameObject == MyGameObject // returns true, far as I know)

Tachyon

Hey Ely,

child.gameObject doesn't work. I tried that already. It just returns null. It's like the objects are stored in the transform of the container and are not objects themselves.

Rigormortis

Hey @Tachyon, any chance you can maybe post the exact error message you get? I'm not an expert, but I'll try to help if I can.

Tachyon

doh! facepalm, sublime's autocorrect placed GameObject instead of gameObject. Works now! What's the difference between the two anyway?

Rigormortis

GameObject is the class, ie the type. gameObject is the instance of the type associated with the transform.

D3zmodos

A gameobject is the container for all the components that an object has attached to it while the transform simply defines it's place in the world (and therefore deals with parent/child object handling)

Tachyon

Right, gotchya @Rigormortis, thanks for the explanation. Since I did not declare it I am assuming that gameObject is an implicit instance in this case?

@D3zmodos - I think you misunderstood the question but thanks anyway ;)

Elyaradine

Er... I don't know the terminology as I'm not a programmer, but unless you create a new Transform in a script, your Transform will always have an associated gameObject reference to the GameObject instance to which it's attached. Like, the gameObject already exists because you've placed/created it in your scene, and no gameObject gets placed without transforms.

If you created a Transform via script... then gameObject might be null (haven't tested that). I don't know whether that means it isn't implicit. :P

[edit] What Herman said below. :P Just tried, and you can't create a Transform in script.

hermantulleken

Edit Hmmm weird double post; original removed.

hermantulleken

It's impossible to create a Transform that is not attached to a gameObject. (You cannot construct Transform, and any field with a Transform value will be linked via the inspector (which means it will always have a gameObject)).

gameObject and transform (and a few others) are just properties defined in the base class Component (see http://docs.unity3d.com/Documentation/ScriptReference/Component.html). I've heard that these just wrap GetComponent calls, for instance transform could be defined as

public Transform transform
{
   get
   {
      return GetComponent<Transform>();
   }
}

which is supposedly why calls to transform are "slow" and some programmers recommend caching the value.