Issue with Lerp outside of update

I have an issue where i want to spawn a random object from an array, then also spawn it at a random point within a given area. after it spawns at a point I want it to move to a target. the issue is I can’t seem to use lerp correctly because the code is done outside of update. so it ends up just at the end destination, rather than animating. is there something i could do that would work?

this spawns the random object from the array in a random position

  public void OnChatMessageReceived(TwitchChatMessage chatMessage)
        {
            if (chatMessage.Message.Contains(headpat))
            {
                bra.SetActive(false);
            }
            if (chatMessage.Message.Contains(thrown))
            {
                int randomIndex = Random.Range(0, myObjects.Length);
                Vector3 randomSpawnPosition = new Vector3(Random.Range(-5, 5), 5, Random.Range(-5, 5));
                GameObject ball = Instantiate(myObjects[randomIndex], randomSpawnPosition, Quaternion.identity);
              
            }
        }

and the code i want to make it lerp to the target would be

ball.transform.position = Vector3.Lerp(transform.position, target.position, 0.1f);

one of my thoughts was just to make it so that when the receive message value hits, it sets something to true and then runs in an update but it seems to break the references like that

Steps to success:

  • review what Lerp() gives you. This is often a common source of misunderstanding. For instance, the above gives you a position 10% of the way FROM transform.position TO target.position.

  • perhaps consider using MoveTowards() instead, as it gives you explicit range-invariant control for easy linear movement.

  • know that unless you DO something with the ball LOCAL variable on line 11 above, nobody else knows about it. The Lerp line certainly would not know about that local variable, unless it was inserted on line 12. Otherwise that local variable dies when that scope closes.

  • verify that Twitch chat callback happens on the main thread, or else you may not use it with Unity API (just a thing to verify; it might be fine)

Regardless of how all of this might interoperate with your chat thing above, this is how to get to the bottom of what is going on:

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 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.

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: How To - Capturing Device Logs on iOS or this answer for Android: How To - Capturing Device Logs on Android

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:

When in doubt, print it out!™

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

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Please don’t remove relevant content from your posts. You make it worthless for others on the forums when you do this. I’ve reverted the code removal.

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