Well simply do your one-time things outside the loop!
Also
randNum = Random.Range(0, 100);
and then you use only 5 different cases and only if the value is smaller 50 (so about in half of the cases nothing happens at all ...). If this was intended .. ok-ish .. otherwise I would rather use a list and random indices:
// HINT: Rather have a list for your prefabs
// this shrinks your code a lot
public List<GameObject/*or whatever type*/> eneymPrefabs = new List<GameObject>();
public Gamebject playerPrefab;
public GameObject endGamePrefab;
private void GenerateEnemies(int xMax, int zMax)
{
var landscape = new GameObject("ENEMIES");
// Do these only once
// store the references in case you need them later
var player = Instantiate(playerPrefab);
var endGame = Instantiate(endGamePrefab);
for (int z = 0; z < zMax; z++)
{
for (int x = 0; x < xMax; x++)
{
// simply pick a random index from the prefab list
int randIndex = Random.Range(0, eneymPrefabs.Count);
// and get the according random prefab
var enemyPrefab = enemyPrefabs[randIndex];
if(enemyPrefab) Instantiate(enemyPrefab, new Vector3(x * 10, 0, z * 10), Quaternion.identity /*, landscape.transform*/);
}
}
}
Or an example for the weighted list mentioned by Draco18s
[Serializable]
public class WeightedPrefab
{
public GameObject Prefab;
public int Weight = 1;
}
public List<WeightedPrefab> weightedEnemyPrefabs;
public Gamebject playerPrefab;
public GameObject endGamePrefab;
private void GenerateEnemies(int xMax, int zMax)
{
// create a temp list using the weights and random index on this one
var enemyPrefabs = new List<GameObject>();
foreach(var item in weightedEnemyPrefabs)
{
for(var i = 0; i < item.Weight; i++)
{
enemyPrefabs.Add(item.Prefab);
}
}
// Rest stays the same
var landscape = new GameObject("ENEMIES");
// Do these only once
// store the references in case you need them later
var player = Instantiate(playerPrefab);
var endGame = Instantiate(endGamePrefab);
for (int z = 0; z < zMax; z++)
{
for (int x = 0; x < xMax; x++)
{
// simply pick a random index from the prefab list
int randIndex = Random.Range(0, eneymPrefabs.Count);
// and get the according random prefab
var enemyPrefab = enemyPrefabs[randIndex];
if(enemyPrefab) Instantiate(enemyPrefab, new Vector3(x * 10, 0, z * 10), Quaternion.identity /*, landscape.transform*/);
}
}
}
If it was intentional that not in every case an enemy is instantiated you can still use both approaches and simply leave a prefab reference empty → for that index nothing will be instantiated.
the enemy and end game should be part of the grid
In this case I would first write the entire grid combinations into a list. Pick two random entries from this list and place the player and the endGame there. Then block these two grid positions and do not spawn enemies there:
[Serializable]
public class WeightedPrefab
{
public GameObject Prefab;
public int Weight = 1;
}
public List<WeightedPrefab> weightedEnemyPrefabs;
public Gamebject playerPrefab;
public GameObject endGamePrefab;
private void GenerateEnemies(int xMax, int zMax)
{
// Create a list of all awailable grid positions
var gridPositions = new List<Vector2Int>();
for (int z = 0; z < zMax; z++)
{
for (int x = 0; x < xMax; x++)
{
gridPositions.Add(new Vector2Int(x,z));
}
}
// pick the two random positions for player and endgame
var playerPosIndex = Random.Range(0, gridPositions.Count);
var playerPos = gridPositions[playerPosIndex];
gridPositions.RemoveAt(playerPosIndex);
var endGamePosIndex = Random.Range(0, gridPositions.Count);
var endGamePos = gridPositions[endGamePosIndex];
gridPositions.RemoveAt(endGamePosIndex);
// create a temp list using the weights and random index on this one
var enemyPrefabs = new List<GameObject>();
foreach(var item in weightedEnemyPrefabs)
{
for(var i = 0; i < item.Weight; i++)
{
enemyPrefabs.Add(item.Prefab);
}
}
var landscape = new GameObject("ENEMIES");
// Do these only once
// store the references in case you need them later
var player = Instantiate(playerPrefab, new Vector3(payerPos.x * 10, 0, playerPos.y * 10), Quaternion.identity /*, landscape.transform*/);
var endGame = Instantiate(endGamePrefab, new Vector3(endGamePos.x * 10, 0, endGamePos.y * 10), Quaternion.identity /*, landscape.transform*/);
for (int z = 0; z < zMax; z++)
{
for (int x = 0; x < xMax; x++)
{
// Now simply ignore the playerPos and endGamePos
if(x == playerPos.x && z == playerPos.y) continue;
if(x == endGamePos.x && z == endGamePos.y) continue;
// pick a random index from the prefab list
int randIndex = Random.Range(0, eneymPrefabs.Count);
// and get the according random prefab
var enemyPrefab = enemyPrefabs[randIndex];
// do nothing if enemyPrefab is null otherwise instantiate
if(enemyPrefab) Instantiate(enemyPrefab, new Vector3(x * 10, 0, z * 10), Quaternion.identity /*, landscape.transform*/);
}
}
}
