Spawning Objects

I thought I had was making progress in my understanding of Unity Script, but apparently I was wrong in that assumption.

I am attempting to "spawn"/instance game objects, orient, and scale game objects after clicking on another object in the scene. At the same point, clicking on the same object again will de-instance/remove the object from the scene.

How would I go about doing this? What scripting references should I look at so I can get a pointed in the right direction ?

 

To spawn new objects use Instantiate (http://docs.unity3d.com/ScriptReference/Object.Instantiate.html). To destroy objects use Destroy (http://docs.unity3d.com/ScriptReference/Object.Destroy.html). To react to mouse clicks, use the OnMouseDown function of a MonoBehaviour (http://docs.unity3d.com/ScriptReference/MonoBehaviour.OnMouseDown.html).

That should get you started.

 

I get this error after Clicking on an object in the game. I have no idea what this error means. Any help?

Code (javascript):

1.  
2. NullReferenceException: Object reference not set to an instance of an object
3. (wrapper stelemref) object:stelemref (object,intptr,object)
4. menuMouseActions.OnMouseDown () (at Assets/scripts/menuMouseActions.js:106)
5. UnityEngine.SendMouseEvents:DoSendMouseEvents(Int32, Int32)
6.  

The error appears on line 106:

Code (javascript):

1.  
2. instanceArray[arrayIndex] = Instantiate(linkObject, transform.position,transform.rotation);
3.  

At this point in the script, arrayIndex is 0, and I have just created my first object via the Instantiate command.

 

Here is the OnMouseDown() function in its entirety:

Code (javascript):

1.  
2. function OnMouseDown()
3. {  
4.    var instanceArray : GameObject[];
5.    var arrayIndex : int = 0;
6.    var tObject : Transform;
7.    var child : int ;
8.    var parentPos : Vector3 = gameObject.transform.position;
9.  
10.    if(selected == false)
11.      selected = true;
12.    else if(selected == true)
13.    {
14.      selected = false;
15.      iconQuad.GetComponent.<Renderer>().material.mainTexture = offImage;
16.      GetComponent.<Renderer>().material.color = offColor;
17.    }
18.  
19.    GetComponent.<Renderer>().material.color = clickColor;
20.    iconQuad.GetComponent.<Renderer>().material.mainTexture = onClickImage;
21.  
22.    for each(Transform in transform)
23.    {
24.    
25.      tObject = Transform;
26.        
27.      if(Transform != iconQuad.transform)
28.      {
29.           if(selected == true)
30.        {
31.          tObject.gameObject.SetActive(true);
32.        }
33.        else if(selected == false)
34.        {
35.          tObject.gameObject.SetActive(false);
36.        }
37.      
38.          // Get Distance to child object
39.          nodeDistance = Vector3.Distance(tObject.position, transform.position);
40.          print(tObject + " distance : " + nodeDistance);
41.          // Instantiate linkObject; object length (z) is 12
42.          instanceArray[arrayIndex] = Instantiate(linkObject, transform.position,transform.rotation);
43.  
44.          // Rotate to face child
45.          print(tObject + ".position is : " + tObject.position);
46.          instanceArray[arrayIndex].transform.LookAt(tObject.position);
47.  
48.      
49.          arrayIndex++;
50.  
51.      }
52.    }
53. }
54.  

I added a bit of error check-point code to see where the error as being thrown. I added the code on line 45, but the script errors out before it hits that. Guess this means I'm screwing something up with the line above it.

Is there a better/smarter way to store a list of instantiated objects so I can modify and later destroy them?

 

instanceArray is null, you can't access an index of a null array! I'm unsure how to actually declare an array in javascript but I'm guessing that's your problem. In C# you would say,

instanceArray = new GameObject[10];...which initializes with a size of 10 that array.

For you, if you don't know how many you will need, I would use the Array class.

http://docs.unity3d.com/ScriptReference/Array.html

 

Updated code:

Code (javascript):

1.  
2. #pragma strict
3. import System.IO;
4.  
5. var onHoverImage : Texture;
6. var onClickImage : Texture;
7. var iconQuad : GameObject;
8. var hoverColor : Color;
9. var clickColor : Color;
10. var linkObject : GameObject;
11.  
12.  
13. private var parentColor;
14. private var pTransform : Transform;
15. private var childCount: int;
16. private var offColor : Color;
17. private var offImage : Texture;
18. private var selected : boolean;
19. private var objCollider : Collider;
20.  
21. private var numChild : int;
22. private var segLength : float = 12.00;
23. private var nodeDistance : float;
24.  
25.  
26.  
27.  
28. function Start ()
29. {
30.    offImage = iconQuad.GetComponent.<Renderer>().material.mainTexture;
31.    selected = false;
32.    offColor = GetComponent.<Renderer>().material.color;
33. }
34.  
35.  
36. function OnMouseEnter()
37. {
38.    if(selected == false)
39.    {
40.      GetComponent.<Renderer>().material.color = hoverColor;
41.      iconQuad.GetComponent.<Renderer>().material.mainTexture = onHoverImage;
42.    }
43. }
44.  
45. function OnMouseExit()
46. {
47.    if(selected == false)
48.    {
49.      GetComponent.<Renderer>().material.color = offColor;
50.      iconQuad.GetComponent.<Renderer>().material.mainTexture = offImage;
51.      
52.    }
53. }
54.  
55.  
56. function OnMouseDown()
57. {  
58.    var instanceArray = new Array ();
59.    var arrayIndex : int = 0;
60.    var tObject : Transform;
61.    var child : int ;
62.    var parentPos : Vector3 = gameObject.transform.position;
63.    
64.    if(selected == false)
65.      selected = true;
66.    else if(selected == true)
67.    {
68.      selected = false;
69.  
70.      iconQuad.GetComponent.<Renderer>().material.mainTexture = offImage;
71.      GetComponent.<Renderer>().material.color = offColor;
72.    }
73.  
74.    GetComponent.<Renderer>().material.color = clickColor;
75.    iconQuad.GetComponent.<Renderer>().material.mainTexture = onClickImage;
76.  
77.    for each(Transform in transform)
78.    {
79.      tObject = Transform;
80.          
81.      if(Transform != iconQuad.transform)
82.      {
83.        if(selected == true)
84.        {
85.          tObject.gameObject.SetActive(true);
86.          // Get Distance to child object
87.          nodeDistance = Vector3.Distance(tObject.position, transform.position);
88.          instanceArray[arrayIndex] = Instantiate(linkObject, transform.position,transform.rotation);
89.          // Rotate to face child
90.          var tempObj = new GameObject();
91.          tempObj =  instanceArray[arrayIndex];
92.          //tempObj.transform.localScale.z = -1;
93.          //tempObj.transform.localScale.x = 0.1;
94.          //tempObj.transform.localScale.y = 0.1;
95.          //tempObj.transform.localScale.z = 0.1;
96.          tempObj.transform.LookAt(tObject.transform.position, Vector3(0,1,0));
97.  
98.          arrayIndex++;
99.        }
100.        else if(selected == false)
101.        {
102.          for(var obj : GameObject in instanceArray)
103.          {
104.            Destroy(obj);
105.            print(obj + " destroyed!");
106.          }
107.          tObject.gameObject.SetActive(false);
108.        }
109.        
110.          
111.  
112.      }
113.    }
114. }
115.  
116.  
117.  

So all the objects are instanced, and now I can manipulate them. The issue I'm running into now is destroying them when I click on the parent object again. For some reason it fails to destroy the instances when "deselecting" the object.