Bug OnTrigger not working

Hello everyone,

im trying to implement a trigger for the "check value" of a dice. Somehow OnGround always returns false. the OnTriggerExit/stay is never called. I tried copying this (18) Unity 5 Tutorial: Physical Dice - YouTube

Code (CSharp):

1.  
2. public class RollTheDice : MonoBehaviour
3. {
4.     Rigidbody rb;
5.     private bool hasLanded;
6.     private bool thrown;
7.     private Vector3 initPosition;
8.    
9.     public int diceValue;
10.     public DiceSide[] DiceSides;
11.  
12.     void Start()
13.     {
14.         rb = GetComponent<Rigidbody>();
15.         initPosition = transform.position;
16.         rb.useGravity = false;
17.         diceValue = 1;
18.     }
19.  
20.     void Update()
21.     {
22.         if(Input.GetKeyDown(KeyCode.Space))
23.         {
24.             RollDice();
25.         }
26.        
27.         if (rb.IsSleeping() && !hasLanded && thrown)
28.         {
29.             Debug.Log("landed correctly");
30.             hasLanded = true;
31.             rb.useGravity = false;
32.             CheckDiceValue();
33.         }
34.         else if (rb.IsSleeping()&& hasLanded&& diceValue== 0)
35.         {
36.             Debug.Log("didnt land correctly");
37.             RollAgain();
38.         }
39.     }
40.  
41.     void RollAgain()
42.     {
43.         Debug.Log("error occured");
44.         ResetIntern();
45.         thrown = true;
46.         rb.useGravity = true;
47.         rb.AddTorque(Random.Range(0, 500), Random.Range(0, 500), Random.Range(0, 500));
48.     }
49.  
50.     private void RollDice()
51.     {
52.         if (!hasLanded && !thrown)
53.         {
54.             thrown = true;
55.             rb.useGravity = true;
56.             rb.AddTorque(Random.Range(0,500),Random.Range(0,500),Random.Range(0,500));
57.         }
58.  
59.         else if (thrown && hasLanded)
60.         {
61.             ResetIntern();
62.         }
63.     }
64.  
65.     private void ResetIntern()
66.     {
67.         transform.position = initPosition;
68.         thrown = false;
69.         hasLanded = false;
70.         rb.useGravity = false;
71.     }
72.  
73.     public void CheckDiceValue()
74.     {
75.         Debug.Log("checking value");
76.         diceValue = 0;
77.         foreach (DiceSide side in DiceSides)
78.         {
79.             Debug.Log("value x");
80.             Debug.Log(side.OnGround());
81.             if (side.OnGround())
82.             {
83.                 diceValue = side.sideValue;
84.                 Debug.Log(diceValue+"this is the result");
85.             }
86.         }
87.     }
88. }
89. public class DiceSide : MonoBehaviour
90. {
91.     private bool onGround;
92.     public int sideValue;
93.  
94.     public bool OnGround()
95.     {
96.         return onGround;
97.     }
98.  
99.     public void OnTriggerStay(Collider col)
100.     {
101.         if (col.tag == "Ground")
102.         {
103.             Debug.Log("true");
104.             onGround = true;
105.         }
106.        
107.     }
108.  
109.     public void OnTriggerExit(Collider col)
110.     {
111.         if (col.tag == "Ground")
112.         {
113.             Debug.Log("false");
114.             onGround = false;
115.         }
116.     }
117. }
118.  
119.  

 

Well we know triggers work so set this all aside and get a trigger working, then revisit your code with the confidence to cross check all the necessary parts.

The official documentation can be helpful here, as it lists a very specific set of requirements to get collider/trigger callbacks.

After that, well, it is time for you to start debugging!

Here is how you can begin your exciting new debugging adventures:

You must find a way to get the information you need in order to reason about what the problem is.

Once you understand what the problem is, you may begin to reason about a solution to the problem.

What is often happening in these cases is one of the following:

- the code you think is executing is not actually executing at all
- the code is executing far EARLIER or LATER than you think
- the code is executing far LESS OFTEN than you think
- the code is executing far MORE OFTEN than you think
- the code is executing on another GameObject than you think it is
- you're getting an error or warning and you haven't noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling

Debug.Log()

statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

- is this code even running? which parts are running? how often does it run? what order does it run in?
- what are the names of the GameObjects or Components involved?
- what are the values of the variables involved? Are they initialized? Are the values reasonable?
- are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as

Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

Visit Google for how to see console output from builds. If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer or iOS: https://forum.unity.com/threads/how-to-capturing-device-logs-on-ios.529920/ or this answer for Android: https://forum.unity.com/threads/how-to-capturing-device-logs-on-android.528680/

If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here's an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://forum.unity.com/threads/coroutine-missing-hint-and-error.1103197/#post-7100494

"When in doubt, print it out!(tm)" - Kurt Dekker (and many others)

Note: the

print()

function is an alias for Debug.Log() provided by the MonoBehaviour class.

 

Based on what you have shown, you do realise that your sphere collider is not a trigger, right? You have to tick the box that says "Is Trigger" for it to use the OnTrigger... methods. Also, is you sphere collider even enabled (just looking at the checkbox for that component seems to indicate that it isn't)?