How to instantiate objects in a circle formation around a point?

Explanation

If you don't really want to know just skip to final code snippet.

The circumferance of a circle is 2 * Pi * r but we can ignore the radius in this case since we only want the spread around the circle, making the function 2 * Pi. Lets say we have 5 enemies. This means each enemy must 2 * Pi / 5 distance around the circle (Radians) away from each other. We'll use num to denote number of enemies making the formula: 2 * Pi / num. If we were to loop through each enemy i, the position of the current one around the circle would be the previous position plus 2 * Pi / num. Meaning to determine the exact radians we can use 2 * Pi / num * i.

 for (int i = 0; i < num; i++){
         
     /* Distance around the circle */  
     var radians = 2 * MathF.Pi / num * i;
     ...
 }

We only have the radians now, but in unity we don't use radians so we need to convert radians into a direction (Vector3) and position (Vector3). To do that we need to fince both the vertcial and horizontal position. For vertical we can use Sin and horizontal we can use Cos. We can the add the new vector3 to the center point to get the spawn direction relative to center point and then multiply it by radius.

 /* Get the vector direction */ 
 var vertrical = MathF.Sin(radians);
 var horizontal = MathF.Cos(radians); 
         
 var spawnDir = new Vector3 (horizontal, 0, vertcial);
         
 /* Get the spawn position */ /* Get the spawn position */ 
 var spawnPos = point + spawnDir * radius; // Radius is just the distance away from the point
 

Now that we have the spawn pos we can simply spawn the enemy, rotate it to look at the player and then adjust height so the enemies don't fall out of the world.

 /* Now spawn */
 var enemy = Instantiate (enemyPefab, spawnPos, Qaurtenion.Identity) as GameObject;
         
 /* Rotate the enemy to face towards player */
 enemy.transform.LookAt(point);
         
 /* Adjust height */
 enemy.transform.Translate (new Vector3 (0, enemy.transform.LocalScale.y / 2, 0));
 

Full Solution

This is how it will look like if we put it all together:

 public GameObject enemyPefab;
 
 public void CreateEnemiesAroundPoint (int num, Vector3 point, float radius){
     
     for (int i = 0; i < num; i++){
         
         /* Distance around the circle */  
         var radians = 2 * MathF.Pi / num * i;
         
         /* Get the vector direction */ 
         var vertrical = MathF.Sin(radians);
         var horizontal = MathF.Cos(radians); 
         
         var spawnDir = new Vector3 (horizontal, 0, vertcial);
         
         /* Get the spawn position */ 
         var spawnPos = point + spawnDir * radius; // Radius is just the distance away from the point
         
         /* Now spawn */
         var enemy = Instantiate (enemyPefab, spawnPos, Qaurtenion.Identity) as GameObject;
         
         /* Rotate the enemy to face towards player */
         enemy.transform.LookAt(point);
         
         /* Adjust height */
         enemy.transform.Translate (new Vector3 (0, enemy.transform.LocalScale.y / 2, 0));
     }
 }    
 

Hope this helpds. If you have any questions let me know.