Search Unity

Problem with grab script

Discussion in 'Scripting' started by SeanTheDeveloper, Sep 21, 2021.

  1. SeanTheDeveloper

    SeanTheDeveloper

    Joined:
    Aug 2, 2020
    Posts:
    25
    Hey there, I am following a tutorial on YouTube on how to create a grabbing script. I tried logging the collision enter and exit, but for some reason it doesn't seem to log the collision.
    This is the code I currently have for the grabbing (2D Project)

    Code (CSharp):
    1.  
    2.     public Transform parent;
    3.     public Transform keyPos;
    4.     bool pickUpAllowed;
    5.  
    6.     void Update()
    7.     {
    8.         if (pickUpAllowed)
    9.         {
    10.             PickUp();
    11.         }
    12.     }
    13.  
    14.     private void OnCollisionEnter2D(Collision2D collision)
    15.     {
    16.         if (collision.gameObject.Equals(parent))
    17.         {
    18.             Debug.Log("Colliding with the player");
    19.             pickUpAllowed = false;
    20.         }
    21.     }
    22.  
    23.     private void OnCollisionExit2D(Collision2D collision)
    24.     {
    25.         if (collision.gameObject.Equals(parent))
    26.         {
    27.             Debug.Log("Not colliding with the player");
    28.             pickUpAllowed = false;
    29.         }
    30.     }
    31.  
    32.     void PickUp()
    33.     {
    34.         transform.SetParent(parent.transform);
    35.         transform.position = keyPos.position;
    36.         transform.GetComponent<Rigidbody2D>().bodyType = RigidbodyType2D.Kinematic;
    37.     }
     
  2. Kurt-Dekker

    Kurt-Dekker

    Joined:
    Mar 16, 2013
    Posts:
    38,745
    You have logging AFTER the collision "is this parent?" check, but why not before it? Find out what you're hitting, print its name, etc.

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

    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

    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 put in Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene

    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.

    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
     
  3. SeanTheDeveloper

    SeanTheDeveloper

    Joined:
    Aug 2, 2020
    Posts:
    25
    Sir, you always comment on every post I make to check my code. The code is running.
     
  4. Kurt-Dekker

    Kurt-Dekker

    Joined:
    Mar 16, 2013
    Posts:
    38,745
    You will need to resolve these two statements. Only one can be correct.