gistfile1.txt

using UnityEngine;
using System.Collections;

public class WaveSpawner : MonoBehaviour {

    public enum SpawnState { SPAWNING, WAITING, COUNTING };

    [System.Serializable]
    public class Wave {
        public string name;//name of the wave
        public Transform enemy;//reference to prefab
        public int count;//the amount of enemies for a wave
        public float rate;//the spawn rate, the higher the number the faster they spawn
    }

    public Wave[] waves;
    private int nextWave = 0;//stores the index of the next coming wave

    public Transform[] spawnPoints;//the enemies spawn from these points

    public float timeBetweenWaves = 5f;//stores the time between waves in seconds
    private float waveCountdown;//?

    private float searchCountdown = 1f;//this is used for our EnemyIsAlive checker method, so that it updates for every second rather than every frame

    private SpawnState state = SpawnState.COUNTING;

    void Start() {
        if (spawnPoints.Length == 0) {
            Debug.LogError("No spawn points referenced.");
        }

        waveCountdown = timeBetweenWaves;//which is currently 5 seconds
    }

    void Update () {
        //killing off the entire wave before a new one spawns
        if (state==SpawnState.WAITING) {
            //check if enemies are still alive
            if (!EnemyIsAlive()) {//this will check if we've any enemies in the screen, FYI !EnemyIsAlive() is the same as EnemyIsAlive()==false
                //begin a new round
                WaveCompleted();
                
                return;
            }
            else {//if we still have enemies alive then we want to return
                return;
            }
        }

        if(waveCountdown <= 0) {
            if (state != SpawnState.SPAWNING) {
                //start spawning wave
                StartCoroutine(SpawnWave(waves[nextWave]));
            }
        }
        else {
            waveCountdown -= Time.deltaTime;//makes sure that the countdown timer stays relevant to time rather than to frames drawn/second, which is currently going to count down from 5
        }
    }

    void WaveCompleted() { //being new round
        Debug.Log("Wave completed");

        state = SpawnState.COUNTING;//counting down
        waveCountdown = timeBetweenWaves;

        if (nextWave + 1 > waves.Length - 1) { //current wave + 1 = next wave, waves.Lenght is the number of waves
            nextWave = 0;//it'll go back and spawn the first wave again
            //here would be the ideal place to put a finish screen e.g. "Yay! You've finished the game!" or increase the stats of the enemies
            Debug.Log("Completed all waves! Looping...");
        }
        else {
            nextWave++;//if you haven't reached the final wave and completed it yet, then this will just continue you to the next level
        }
    }
    //this is very resource demanding, so rather than updating for every frame it should only be updated every second
    bool EnemyIsAlive () {
        searchCountdown -= Time.deltaTime;
        if (searchCountdown <= 0f) {//if searchCountdown is less or equal to 0 seconds then it will run the next if statement below
            searchCountdown = 1f;//when our countdown reaches 0 and enemies are still alive then we want the countdown to check again in one second
            if (GameObject.FindGameObjectsWithTag("Enemy") == null) {//returns an array of all enemies/gameobjects with this game tag
                return false;//meaning that no enemies are alive, so if that's the case then the next wave WILL spawn
            }
        }
        return true;//meaning that some enemies are alive, so if that's the case then the next wave WON'T spawn
    }
    

    IEnumerator SpawnWave(Wave _wave) {//waits a certain amount of seconds inside of the method, which is why we're using IEnumerator rather than a void
        Debug.Log("Spawning Wave: "+ _wave.name);
        state = SpawnState.SPAWNING;

        //spawn
        for (int i = 0; i < _wave.count; i++) {//will run the amount of enemies we want to spawn
            //spawn an enemy
            SpawnEnemy(_wave.enemy);
            yield return new WaitForSeconds(1f / _wave.rate);//waits a certain amount of seconds before looping again and spawning a new enemy, this is why we're using IEnumerator
        }

        state = SpawnState.WAITING;//?

        yield break;//will return nothing, always use this when dealing with IEnumerator
    }

    //remember to go to prefabs and tag the enemy as "Enemy" in the inspector for all the enemies you want to be spawning
    void SpawnEnemy (Transform _enemy) {
        Debug.Log("Spawning Enemy: " + _enemy.name);

        Transform _sp = spawnPoints[Random.Range(0,spawnPoints.Length)];//?
        //enemy spawn point
        Instantiate(_enemy, _sp.position, _sp.rotation);
        //Instantiate(_enemy, transform.position, transform.rotation);//spawn point location //you can also use Vector3 if you like 
    }

}
    /*
    after finishing the code: 
    create an empty gameobject in Unity -> name it EnemySpawnPoint -> give it an icon so it's easier to see -> make it into a prefab -> 
    then you can make multiple spawn points if you desire (the Random.Range at line 110 should make enemies spawn from one of the spawn points randomly) -> 
    drag all of the spawn points into the spawn points elements where the C# Script has been added to -> hit apply and you should be done!
    */