How Can I Fix Spawning The Tiles?

Question

I am making a 3D infinite runner game in Unity in C#. When the player has reached the end of the tile it should spawn another tile and then delete the previous tile. When the player reached the end of the first tile it deletes that tile and spawns another(just like it should), but when the player reached the second tile is does nothing. Does someone have a solution?

Thanks

Here is my code: Old:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Terrain : MonoBehaviour
{
    private List<GameObject> objs = new List<GameObject>();
    public GameObject terrain;
    public GameObject terrain2;
    public GameObject player;
    //private float z = 4130.875f;
    private float safeZone = 260.0f;
    private float tileLength = 260.0f;
    private int animTilesCount = 2;
    private Vector3 position;
    void Start()
    {
        objs.Add(terrain);
        objs.Add(terrain2);
        for (int i = 0; i < animTilesCount; i++)
        {
            spawnTile();
        }
    }
    void Update()
    {
        if ((objs.Count > 1) && (player.transform.position.z - objs[0].transform.position.z > safeZone))
        {
            spawnTile();
            DeleteTile();
        }
    }

    public void spawnTile()
    {
        position = objs[objs.Count - 1].transform.position;
        position.z += tileLength; //21, -13
        position.x += 21;
        position.y += -13;

        GameObject go = Instantiate<GameObject>(
                      terrain,
                      position,
                      terrain.transform.rotation);

        go.transform.SetParent(transform);

        objs.Add(go);
    }

    public void DeleteTile()
    {
        Destroy(objs[0]);
        objs.RemoveAt(0);
    }
}

New:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Terrain : MonoBehaviour
{
    [SerializeField]
    private List<GameObject> objs = new List<GameObject>();
    public GameObject terrainPrefab;
    public GameObject player;
    public GameObject terrain;
    public GameObject terrain2;
    //private float z = 4130.875f;
    private float safeZone = 260.0f;
    private float tileLength = 260.0f;
    private int animTilesCount = 2;
    private Vector3 position;
    void Start()
    {
        objs.Add(terrain);
        objs.Add(terrain2);
        for (int i = 0; i < animTilesCount; i++)
        {
            spawnTile();
        }
    }
    void Update()
    {
        if ((objs.Count > 1) && (player.transform.position.z - objs[0].transform.position.z > safeZone))
        {
            Debug.Log("Hello");
            spawnTile();
            DeleteTile();
        }
    }

    public void spawnTile()
    {
        position = objs[objs.Count - 1].transform.position;
        position.z += tileLength; //21, -13
        position.x += 21;
        position.y += -13;

        GameObject go = Instantiate<GameObject>(
                      terrainPrefab,
                      position,
                      terrainPrefab.transform.rotation);

        go.transform.SetParent(transform);

        objs.Add(go);
    }

    public void DeleteTile()
    {
        Destroy(objs[0]);
        objs.RemoveAt(0);
    }
}

Answer 1

You're trying to use the first tile in the map as your source for spawning new tiles.

GameObject go = Instantiate<GameObject>(terrain, ...

But the first tile in the map is also the first one you destroy when the player gets far enough.

Destroy(objs[0]);

Once it's destroyed, you no longer have a source tile to use for spawning new copies. So no future tiles can spawn.

So, you have two different jobs here. Separate them.

• Source for spawning tiles: prefab

  Take one of your tile objects and drag it into your Project folder. This creates what's called a Prefab asset. It's an archetype of the object that exists outside your scene, and you can use it as the source object to copy from when you want to Instantiate new copies.

  Prefabs are also useful for batch-updating many similar objects across multiple scenes: update the prefab, and its spawned copies will inherit the changes.

  Add a public GameObject terrainPrefab; variable to your script, and assign your prefab object from the Project folder into it.

  Change your spawning line to use this prefab: Instantiate<GameObject>(terrainPrefab, ...

• Tiles currently in your map: objs list

  Add a [SerializeField] attribute above your private List<GameObject> objs = new List<GameObject>(); line. This will make it show up in the Inspector, so you can add your initial level tiles to it directly.

  Now you can delete your terrain and terrain2 variables and the calls to Add() them on start. They're already part of the list because you put them there.

Now you're never using a scene object / list member as a spawning source, and you can't accidentally delete your source tile.

Answer 2

I can see at least one other problem with your code. When spawning a new tile, you set its rotation by accessing terrain.transform after destroying it. This would cause a null reference exception and fail to spawn the tile.

Are there any errors being printed to the console?