IEnumerator SpawnWaves()
    {
        yield return new WaitForSeconds(startWait);
        while (true) {
            if (waves < waveCount && !gameOver)
            {
                for (int i = 0; i < hazardCount; i++)
                {
                    //pick a random enemy from array
                    GameObject hazard = hazards[Random.Range(0, hazards.Length)];
                    Vector3 spawnPosition = new Vector3(Random.Range(-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
                    Quaternion spawnRotaion = Quaternion.identity;
                    Instantiate(hazard, spawnPosition, spawnRotaion);
                    yield return new WaitForSeconds(spawnWait);//how long until next enemy is spawned
                }
            }

            if (!gameOver && !bossDead)
            {
                waves++;
                Debug.Log("Wave(s): " + waves);
                yield return new WaitForSeconds(waveWait);//how long until next wave is spawned
            }

           if (waves == waveCount && !gameOver)
            {
                //change to the boss music
                AudioSource audio = GetComponent<AudioSource>();
                audio.clip = bossMusic;
                audio.Play();

                //spawn the boss
                Vector3 bossSpawnPositon = new Vector3(0f, 0f, 20f);
                Quaternion spawnRotaion = Quaternion.identity;
                Instantiate(boss,bossSpawnPositon,spawnRotaion);
                Debug.Log("Boss spawned");
            }

            if (waves >= waveCount && !gameOver && GameObject.FindWithTag("Enemy") == null && !bossDead)
            {
                bossDead = true;

                //change to the boss killed music
                AudioSource audio = GetComponent<AudioSource>();
                audio.clip = bossKilled;
                audio.Play();
                yield return new WaitForSeconds(3f);
                audio.clip = scoreMusic;
                audio.Play();
            }


            if (gameOver)
            {
                yield return new WaitForSeconds(2f);
                restartText.text = "Press 'Fire' for restart";
                restart = true;
                break;
            }
        }
    }