Question by MattiGroot · Sep 12, 2014 at 06:39 PM · sendmessage

Unity SendMessage with Parameter not working

Dear Unity Answers Community,

Though the title is somewhat unclear, I think I can explain it easily below: My mouse input simply checks if it hit an object, if it does. It sends a message to the object and stores the object in a variable. When the mouse input hits another object, I wanted to send a message with the already defined object as parameter. So the receiving script can target that object. Here are the two functions that matter:

 void MouseClick(){
         beginMousePosition = Input.mousePosition;
         panVector = GetMousePos ();
         Ray ray = Camera.main.ScreenPointToRay(beginMousePosition);
         RaycastHit hit ;
         if (Physics.Raycast (ray, out hit)) {
             if(hit.collider.transform.tag == "SelectionCollider"){
                     GameObject objectToSend = selectedObject;
                     hit.transform.SendMessage("OnSelected", objectToSend);
                     selectedObject = hit.transform.gameObject;
             }
             else {
                 if(selectedObject != null){
                     hit.transform.SendMessage("OnSelected");
                     selectedObject = null;
                 }
             }
         }
     }

Receiving function:

 void OnSelected(){
         if(!selected){
             Select ();
         } else {
             UnSelect();
         }
     }
     
     void OnSelected(GameObject selectedObject){
         Debug.Log ("Not receiving in this function");
         if (!selected) {
             Select();
         } else {
             if(selectedObject == null){
                 UnSelect();
             }
             else {
                 HandleSecondSelect(selectedObject);
             }
         }
     }

The first time I select an object with my mouse, it enters the empty receiving function as it needs to. However the second time (when the objectToSend has a reference) it's also received in the empty receiving function.

Does anybody know why the 1 parameter receiving function doesn't get triggered?

Thanks in advance,

Greatings Matti.

Add comment · Show 6

rutter · Sep 12, 2014 at 06:40 PM 0

I'm not sure if Send$$anonymous$$essage plays nice with overloaded functions. You might need two distinct names to call, or you could pass null, or find some other workaround.

MattiGroot · Sep 12, 2014 at 07:08 PM 0

I've added the overloaded functions later, because when I didn't have the empty parameter function, unity gave an error saying that the receiver asks for 1 parameter. Which I most certainly passed with Send$$anonymous$$essage. I know there are some workarounds, but this approach would really be nice in my case. Edit: There was a case when I passed down null, im going to check if that was the problem. 2nd Edit: Didn't seem to be the problem.

yoyo · Sep 13, 2014 at 06:42 AM 0

Just pass null when you don't want to pass an object (line 14 in your first code snippet). You already have a null check in the receiver, so that Should Just Work.