Question How to Destroy Object......

I have an object in my project called "Drop". And I have another object "DropFader" with just a collider and a script attached to it. The script is:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class DropFader : MonoBehaviour
6. {
7.     [SerializeField]
8.     private Animator drop;
9.  
10.     private void OnTriggerEnter2D(Collider2D collision)
11.     {
12.         if (collision.CompareTag("Drop"))
13.         {
14.             drop.SetBool("ShouldFade", true);
15.             StartCoroutine(OneSecond());
16.         }
17.     }
18.  
19.     private IEnumerator OneSecond()
20.     {
21.         yield return new WaitForSeconds(1.0f);
22.         drop.SetBool("ShouldFade", false);
23.         Destroy(drop);
24.     }
25. }

When Drop hits the collider of DropFader a boolean in Drop's animator is changed and a short delay later Drop gets destroyed. Everything works like a charm BUT all hell breaks loose when I make Drop a prefab. Either I can't destroy Drop no more because Unity does not allow the destruction of a prefab and when I instantiate Drop the DropFader does not trigger the animation nore does he destroy the instance of Drop.
How can I make this work?

 

That's your first clue. Don't drag a prefab into that

drop

slot.

That variable should be named

dropPrefab

to help you understand its purpose.

If that must be a prefab, then you must make a working copy of it with Instantiate and keep the reference that Instantiate returns so that you can Destroy() that instance copy.

Otherwise, it just sounds like standard bugs:

Time 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 for 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.

If your problem is with OnCollision-type functions, print the name of what is passed in!

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.

 

Thanks a lot for all the input. I'll try to follow it step by step.

 

Code (CSharp):

1.     private void OnTriggerEnter2D(Collider2D collision)
2.     {
3.         if (collision.CompareTag("Drop"))
4.         {
5.             collision.gameObject.GetComponent<Animator>().SetBool("ShouldFade",true);
6.             Destroy(collision.gameObject,1);  // destoy drop in one second
7.         }
8.     }