Is gameObject present at coordinates (x,y,z)?

Questions & Answers
1

Hi, Bit of a beginner at unity and at Javascript coding in general. I'm making a 2d platformer game where objects can be controlled using a tracked fiducial marker. My main issue is that I struggle to find out what things are called in Unity in order to reference them in the code (the Unity resources are helpful, but sometimes a bit hard going).

Anyway, I've got some code which finds the x and y co-ordinates of a cube (and the rotation too) being controlled by the tracked fiducial, and now i want to use it's x & y co-ordinates in a loop to check if a gameobject exists at the co-ordinates ((myPosition), (myPosition2), z) on a loop where z = 0-50. After that i can work on making that secondary gameobject movable.

Heres my current code:

-function Update() {
   myPosition = transform.position.x;
   myPosition2 = transform.position.y;
   myRotation = transform.rotation.eulerAngles.z;
   Debug.Log(myPosition);
   Debug.Log(myPosition2);
   Debug.Log(myRotation);
}

//function Update() {
//For (z=0; z<50, z++){
//if (gameObject)

The code at the bottom is some early attempts at it before i realised i had no idea how to check if something was at a co-ordinate. I'm assuming my idea that i could just check if gameobject = true at co-ordinates (myPosition, myPosition2, z) is probably wrong, as I think that would end up as a vector3 instead of a location co-ordinate?

So my issues are 1. How do I check if a gameobject exists at a location? 2. can i use variables in a co-ordinate for a location to check? 3.Is a For loop the best way to check the z distance at my x,y co-ordinates, or am i doing this all wrong? 4. Oh and lastly, as a bonus question, once i find an object, i need to stop the loop. how do i do that?

Sorry for lots of questions, hopefully i'll get the hang of this quickly and bother you guys less :D

2

In my opinion you should use OnTriggerEnter(col:Collider) and OnTriggerStay(col:Collider). http://unity3d.com/support/documentation/ScriptReference/Collider.OnTriggerEnter.html

1-3. So: Attach trigger sphere with radius 50(or what u need) to your marker position. Just create sphere, make it a trigger, set its coords equal to your marker coords. And it should be a child of your marker. Then write a script using OnTriggerEnter(col:Collider) and OnTriggerStay(col:Collider). Attach script to sphere. And when smth enters this trigger it will call function OnTriggerEnter which should send collision(better) or 'true'(not very good) to your main script.

4 To stop loop use next constructions:

for (k=0; k<50; k++)
{
//some code
//ex1t=true when obj find
//...
if (ex1t) break; //break exits loop; ex1t - any boolean var
}

OR

for (k=0; (k<50)&&(!ex1t); k++) //loop continues while ex1t is false and k<50
{
//ex1t=true when obj find
//...
}