enemy random

How to make the enemy’s location is randomly appear?
Appears from both sides of the screen
And when out of range of the screen will be destroyed?
How can I do?

Here is my advice:

  1. You could let your enemies spawn at completely arbitrary points, and that may be useful for some games, but that is easy to implement ( Instantiate(enemy, new Vector3(Random.Range(), 0, Random.Range() ), Quaternion.Idenity) ) so I will give an example of the slightly more complicated model. I would suggest having a collection of SpawnPoints then just randomly picking one. This will give your more control to make sure that enemies are spawned in reasonable places. So, you want to create a collection of Spawn points. Just place empty GO’s around the scene where you want them.

     var enemyCount = 3;
     var actualCount = 0;
     var enemyPrefab : GameObject;
     var spawnPoints : SpawnPoint[];
     function Start () {
           spawnPoints = FindObjectsOfType(SpawnPoint) as SpawnPoint[];
           //Create a script called spawnpoint and attach it to your spawnpoints.
            while(actualCount < enemyCount) {
                     pos : Vector3 = spawnPoints[Random.Range(0 , spawnPoints.Length)].transform.position;
        function CreateEnemy (spawnPoint : Vector3) {
              Instantiate(enemyPrefab, spawnPoint, Quaternion.Identity);
         //Note that this is very simple and I didn't really check it so there is a good chance there is a minor mistake.
  2. Then Random.Range() should make sure that the spawn points will be used equally so you won’t have to worry about getting a variety. You might want to yield the value a frame to make sure the random number generator doesn’t take the same seed twice in a row.