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Get last spawned object's position

Discussion in 'Scripting' started by unity_nVdYtceNQmOPDw, Dec 3, 2019.

  1. unity_nVdYtceNQmOPDw

    unity_nVdYtceNQmOPDw

    Joined:
    Jun 12, 2018
    Posts:
    15
    Hi!
    I'm using a for loop to spawn objects,and i would like to have x amount of space between the spawned objects.
    But if i do it like this,it starts to make the given space bigger and bigger.

    Code (CSharp):
    1.  
    2.  void Update()
    3.     {
    4.         randomSpace = Random.Range(minSpawnSpace, maxSpawnSpace);
    5.     }
    6.  
    7. for (int i = 0; i < length; i++)
    8.         {
    9.             randomNumber = PickANumber(-1, 1);
    10.             Vector3 pos = new Vector3(transform.position.x + randomNumber, transform.position.y, i * randomSpace);
    11.             int index = Random.Range(0, objects.Length);
    12.             cube = Instantiate(objects[index], pos, transform.rotation);
    13.             cube.transform.parent = transform;
    14.         }
    I think it's because when the "i" variable starts to get bigger the gap between the objects multiplying in a wrong way.
    So i think if i could get the last spawned object's position and added the random space to it's transform.position.z,it would work but i don't know how to do it.
    Thanks in advance.
     
    Last edited: Dec 3, 2019
  2. Ardenian

    Ardenian

    Joined:
    Dec 7, 2016
    Posts:
    92
    The problem seems to be here:
    Code (CSharp):
    1.  
    2.             int index = Random.Range(0, objects.Length);
    3.             cube = Instantiate(objects[index], pos, transform.rotation);
    4.  
    You use an object that already has an offset as a base for instantiating another object. I wouldn't be surprised if the instantiated object has the position
    pos + objects[index].transform.position
    .

    Use a general prefab object instead. See also Prefabs (Unity Manual).
     
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  3. unity_nVdYtceNQmOPDw

    unity_nVdYtceNQmOPDw

    Joined:
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    Posts:
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    I tried it like this but it's still working the same way:
    Code (CSharp):
    1.             cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
    2.             cube.transform.position = pos;
     
  4. Ardenian

    Ardenian

    Joined:
    Dec 7, 2016
    Posts:
    92
    Hm, I see, could you post the whole code, please? It is not very clear in your initial code what is what.

    I had that weird exponentially increasing offsets in the past, too, I am confident that at some point, you use a transform of an object that already has an offset. If you post the whole code, I can run some quick tests myself.
     
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  5. unity_nVdYtceNQmOPDw

    unity_nVdYtceNQmOPDw

    Joined:
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    Posts:
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    Yes of course,thank you for helping.
    Code (CSharp):
    1. using UnityEngine;
    2.  
    3. public class SpawnScript : MonoBehaviour
    4. {
    5.     private GameObject cube;
    6.     public int length;
    7.     public float randomSpace;
    8.     float randomNumber;
    9.  
    10.     //-------------
    11.     private float minSpawnSpace = 5f;
    12.     private float maxSpawnSpace = 5f;
    13.  
    14.  
    15.     //random rotation
    16.     //spawn rate
    17.  
    18.     //position and rotation
    19.     private Vector3 positionX;
    20.     private Vector3 positionY;
    21.  
    22.     void Start()
    23.     {
    24.         Spawn();
    25.     }
    26.  
    27.     void Update()
    28.     {
    29.         randomSpace = Random.Range(minSpawnSpace, maxSpawnSpace);
    30.     }
    31.  
    32.     void SpawnX()
    33.     {
    34.  
    35.         for (int i = 0; i < length; i++)
    36.         {
    37.             randomNumber = PickANumber(-1, 1);
    38.             Vector3 pos = new Vector3(transform.position.x + randomNumber, transform.position.y, i * randomSpace);
    39.             cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
    40.             cube.transform.position = pos;
    41.             cube.transform.parent = transform;
    42.         }
    43.     }
    44.  
    45.     void SpawnY()
    46.     {
    47.         for (int i = 0; i < length; i++)
    48.         {
    49.             randomNumber = PickANumber(-1, 1);
    50.             Vector3 pos = new Vector3(transform.position.x, transform.position.y + randomNumber, i * randomSpace);
    51.             cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
    52.             cube.transform.position = pos;
    53.             cube.transform.parent = transform;
    54.         }
    55.     }
    56.  
    57.     void Spawn()
    58.     {
    59.         SpawnX();
    60.         SpawnY();
    61.     }
    62.  
    63.     int PickANumber(int first, int second)
    64.     {
    65.         int[] numbers = new int[] { first, second };
    66.         int index = Random.Range(0, numbers.Length);
    67.         int result = numbers[index];
    68.         return result;
    69.     }
    70. }
    71.  
     
  6. Ardenian

    Ardenian

    Joined:
    Dec 7, 2016
    Posts:
    92
    Thanks, I used it and it doesn't appear to increase the space, see the attachment. How does it look for you? I used a length of 100 with a space of 5. Even with setting minSpawnSpace and maxSpawnSpace to different values, to a range, didn't change that.

    What Unity version are you using?
     

    Attached Files:

  7. unity_nVdYtceNQmOPDw

    unity_nVdYtceNQmOPDw

    Joined:
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    Posts:
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    This is how it acts when i try it.
    Did you try it with 3d objects?
     

    Attached Files:

  8. Ardenian

    Ardenian

    Joined:
    Dec 7, 2016
    Posts:
    92
    Except for that red thingy, it does look exactly like mine. How should it look like?

    PS: draw.io is a nice website for quickly drawing a sketch or construct a shape.
     
  9. unity_nVdYtceNQmOPDw

    unity_nVdYtceNQmOPDw

    Joined:
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    Posts:
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    This is what i mean.
    And i don't understand why it leaves out so much space sometimes.
     

    Attached Files:

  10. Ardenian

    Ardenian

    Joined:
    Dec 7, 2016
    Posts:
    92
    Sorry, I genuinely don't get it.

    With your spawn script, you create an array of two objects, every time with one being slightly off in x and the other one being slightly off in y. Between two of these cubes and two other ones, there is a random space in z direction. This random space is at least
    minSpawnSpace
    and no larger than
    maxSpawnSpace
    .

    However, when I look at the screenshot that you posted, I see exactly that. I don't understand why you see the right space to the left and right and a supposedly huge amount of space in the middle.

    Do you not want cubes sharing the same x and y coordinates to be too far off from each other?
     
  11. unity_nVdYtceNQmOPDw

    unity_nVdYtceNQmOPDw

    Joined:
    Jun 12, 2018
    Posts:
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    No the offsets on the x and y are good,but it seems to me that it's leaving larger amount of spaces on the z axis than the maxSpawnSpace.But sometimes,as i drew on the picture,the spaces are the riight amount but sometimes it's not.At least it's seems like it.
     
  12. Ardenian

    Ardenian

    Joined:
    Dec 7, 2016
    Posts:
    92
    You could log the difference in z between an previously spawned object and a just spawned object to see if it is true.
    It could look something like this:
    Code (CSharp):
    1. GameObject previous = null;
    2. for(int i = 0; i < length; ++i){
    3.  
    4.     // spawn object
    5.  
    6.     if(previous != null){
    7.         Debug.Log(cube.transform.position.z-previous.transform.position.z);
    8.     }
    9.     previous = cube;
    10. }
    To ease your eyes and mind, you could also write:
    Code (CSharp):
    1.         float difference = cube.transform.position.z-previous.transform.position.z;
    2.         Debug.Log(difference >= minSpawnSpace && difference <= maxSpawnSpace);
     
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  13. unity_nVdYtceNQmOPDw

    unity_nVdYtceNQmOPDw

    Joined:
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    Posts:
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    Yes it really did send back the right values.Thank you for replying!
     
  14. Ardenian

    Ardenian

    Joined:
    Dec 7, 2016
    Posts:
    92
    You are welcome! :)
     
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