2D Function analyzing if there is a Gameobject where you click ?

Hi everybody !

I’m making a little game with objects appearing when I click. I have this code actually making things work : everytime I use the mouseclick a Gameobject is created where I click on the 2d game I created.

 //Changed to an array of objects assign as many as you have in inspector
    var boxes : GameObject[];
    var boxCounter : int;
     
    function Update()
    {
    if(Input.GetMouseButtonDown(0))//Checks to see if left mouse button was clicked.
    {
    CreateBox();
    }
    }
     
    function CreateBox()
    {
    var mousePos : Vector2 = Input.mousePosition;
     
    //Depth you want the center of the object to be is z which I used zero
    var boxPos : Vector3 = camera.ScreenToWorldPoint(mousePos.x, mousePos.y, 0);
     
    //I used the perfab box's rotation here but you can enter what you'd like as a euler using Quaternion.Euler(x,y,z)
    Instantiate(boxes[boxCounter], boxPos, boxes[boxCounter].transform.rotation);
     
    //This will increment if there are more boxes or reset to 0 if it is the last one.
    if(boxCounter == boxes.length-1)
    {
    boxCounter = 0;
    }else{
    boxCounter ++;
    }
    }

I want to add a function to avoid the creation of the object if there is already another one where I clicked. I don’t know if I can do a simple function like If onclick there is a gameobject nothing happened; or if I have to do something like when I click create a gameobject, if collision cancel it, if not go for the Createbox function. I don’t know exactly how to do that, any idea?

Thanks in advance !

I suggest using Physics.OverlapSphere with the OnClick method.

This way you can set the radius to decide on how far from other boxes you can place the new box.

EDIT:

I noticed you are using unity 2d, so a better function would be Physics2D.OverlapCircle.

Bellow is a tested example of how I made this work.

var boxes: GameObject[];
var boxCounter: int;

function Start() {
	boxCounter = 0;
}

// Update is called once per frame
function Update() {
    if (Input.GetMouseButtonDown(0)) //Checks to see if left mouse button was clicked.
    {
        CreateBox();
    }
}

function CreateBox() {
    var mousePos: Vector2 = Input.mousePosition;

    //I used 10 for the depth here because camera is at -10. This means all boxes will be created at Z = 0
    var boxPos: Vector3 = Camera.main.ScreenToWorldPoint(Vector3(mousePos.x, mousePos.y, 10));

	//OverlapCircle helps us know if there is a collider in a specific circle
	//So we overlap a circle where we want to place the new box
    var collider = Physics2D.OverlapCircle(Vector2(boxPos.x, boxPos.y), 0.5f);

	//If no other colliders (boxes) exist at the new position, create our new box
    if (collider == null) {
        Instantiate(boxes[boxCounter], boxPos, boxes[boxCounter].transform.rotation);
    }

    //This will increment if there are more boxes or reset to 0 if it is the last one.
    if (boxCounter == boxes.length - 1) {
        boxCounter = 0;
    } else {
        boxCounter++;
    }
}

I would suggest you to handle the problem like this :

  • OnClick → make a raycast (see doc)
  • if the raycast hits a collider (this supposes that your created game objects have one), do nothing
  • else you create your game object.

Instantiate and destroy are far more heavier than a ray cast.

Hi ! Thanks about this. How do you make the function overslap work in tis case? I tried without succes …

if (Input.GetMouseButtonDown(0)) { //when user touches the screen
RaycastHit hit = new RaycastHit ();
if (Physics.Raycast (ray, out hit)) {
//if it is a box
if (hit.transform.CompareTag (“Box”)) {
//then do nothing }
else
CreateBox()
}
}

Just put this code in your update function …and you are good to go

Note* Set you box tag as “Box”