AI scripting doubts.

Unity Engine
1

Hello,

I’m building a shoot’em up where a script called “Scene_Director” instantiates the waves of enemies at regular times.
Now, each single enemy of each single wave has to follow a path which will be different from another enemy of the same wave, so, I built a script called “PatternScript” which basically holds a bunch of methods which (depending on an argument I’m passing from the Scene_Director) will move the enemy through a path.
In code:

Scene_Director:

public class TestScene_DirectorScript : MonoBehaviour {

    private float time;

    private bool[] flags = new bool [10];    // tool for controlling waves

    public Transform enemy1_prefab;

    // Use this for initialization
    void Start () {
        time = 0;
        for (int i = 0; i < 10; i++)
            flags [i] = false;
    }
  
    // Update is called once per frame
    void Update () {
        time += Time.deltaTime;
        if (time > 1.0f && flags[0] == false)
        {  
            flags [0] = true;
            WaveOne ();
        }
    }

    void WaveOne()
    {
        var spawn = Instantiate (enemy1_prefab) as Transform;
        spawn.position = new Vector3 (-2.0f, 4.0f, 5.0f);
        MovePatternScript mvs = spawn.GetComponent<PatternScript> ();
        mvs.SetTargetPos (new Vector3(-2.0f, 0.0f, 5.0f));
        mvs.SetPattern (1);
        spawn = Instantiate (enemy1_prefab) as Transform;
        spawn.position = new Vector3 (2.0f, 4.0f, 5.0f);
        mvs = spawn.GetComponent<PatternScript> ();
        mvs.SetTargetPos (new Vector3(-2.0f, 0.0f, 5.0f));
        mvs.SetPattern (1);
    }
}

PatternScript:

public class PatternScript : MonoBehaviour {

    public int pattern = 0;

    private bool initializated;

    private Vector3 v;
    private Vector3 movement;
    public Vector3 targetPos;

    // Use this for initialization
    void Start () {
        targetPos = new Vector3 (0.0f, 0.0f, 5.0f);
    }
  
    // Update is called once per frame
    void Update () {
      
        switch (pattern)
        {
            case 1:
                PatternOne ();
                break;
            case 2:
                break;
            case 3:
                break;
            case 4:
                break;
        }

    }

    public void SetPattern(int n)
    {
        pattern = n;
    }

    public void SetTargetPos(Vector3 x)
    {
        targetPos = x;
    }
      
    void PatternOne()
    {
// Example, it might also be a Bezier Curve
        transform.position = Vector3.MoveTowards (transform.position, targetPos, 0.05f);
    }
}

You see how TEDIOUS it is? The Scene_Director has, for each enemy, grab the Pattern_Script, point the target position and which pattern to use. Also, you need to write at least 5 lines of code for each enemy, while a wave usually holds 10+ enemies. Plus, that is the easiest pattern, try to figure out how to describe a Bezier Curve.

In C++ it would be extremely easy by having a custom constructor:

Enemy::Enemy(glm::vec3 startPos, glm::vec3 endPos, int pattern)
{
// spawn the enemy at startPos, bring it to endPos using pattern
}

So you can call:

Enemy* e = new Enemy (glm::vec3, glm::vec3, int)

Finally, the question is: what solution do you suggest to shorten and optimize the code for Scene_Director/Pattern_Script by also keeping an eye to abstraction?

Sorry for the long post, thanks in advance.

2

You can use constructors in C# too.

You can actually go one better and expose it all to the inspector. This makes configuration and iteration really, really easy.

3

Could you please post an example of an instatiation of a prefab through a C# constructor? As you can see I’m pretty newbie in C#, my territory is more C++. :slight_smile:

Exposing everything to the inspector is not a problem, but this implies having 100+ disabled gameobjects on my scene. Isn’t it? Or am I missing something important?

4

All good. You can’t build a constructor for a MonoBehaviour, as Unity runs its own special constructor. But you can build a constructor on a vanilla class and pass that through to your MonoBehaviour.

Yes. You can expose vanilla classes to the inspector in a collection on a single GameObject or ScriptableObject.

This is generally how I code wave like behavior.

public class WaveGenerator : MonoBehaviour {
    [SerialiseField]
    List<Wave> waves;

    void Start (){
        StartCoroutine(GenerateWaves());
    }

    IEnumerator GenerateWaves (){
        foreach (Wave wave in Waves){
            yield return new WaitForSeconds (wave.delayTime);
            // Instantiate the wave
        }
        yield return null;
    }
}

[System.Serialisable]
public class Wave {
    public GameObject enemyPrefab;
    public int noOfEnemies;
    public float delayTime;
}

You can follow the same pattern to set up the various patterns. Just expose a List and in each Pattern expose a List.

Does that make sense?

5

Yes! This is great! I’m gonna give it a try now.

Thanks a lot for your help! Later on I’ll post here the result and/or any problem if you don’t mind. :stuck_out_tongue:

Thanks again!