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For Loop Headaches

by Gina-Marie -Netjera- Hammer · in Torque Game Builder · 03/24/2005 (3:57 am) · 3 replies

I'm trying to use a for loop to schedule enemies and to determine when all the enemies have deployed. After all enemies have deployed, the level should end with a "Level End" screen.

Here's the code I'm using:

// Spawn all the enemies
	for (%i=0; %i< $nEnemies; %i++)
	{
		// If this is the first enemy of the level, create an enemy
		if (%i == 0)
		{
			createEnemy();
		}
		// If this is not the first enemy of the level, wait a bit, then create another one
		else
		{
			schedule(2000, 0, "createEnemy()");
		}
	}
		
	// End the level
	if (%i == $nEnemies)
	{
		$player.setVisible( false );
		playerMap.pop();
		showLevelEnd();
	}

These are just two parts of the function.

Here's my problem. The for loop iterates, schedules all of the enemies, and exits the loop before all of the enemies have been deployed. So essentially, I have a "Start Level" screen, and then it immediately goes to the "End Level" screen, even though I can still see the particle effects from the ship in the background. This brings me to two questions:

1) Is there some way to pause the for loop, so that it doesn't iterate again until after the enemy has been deployed (not just scheduled);
2) If not, is there some way to check to see if all the enemies have been deployed (something along the lines of "if instance_exists" if anyone here has used GML)?

Thanks!
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Torque Owner Greg Lincoln
#1
03/24/2005 (4:27 am)
1. You might consider incrementing your enemy count in this function instead of in createEnemy. Another option is to have the first enemy case handled in your startup stuff which seems to execute before the first frame. You can have createEnemy schedule itself for subsequent ones.

2. I think isObject() might be what you are looking for here.

Torque Owner Gary Preston
#2
03/24/2005 (4:55 am)
Maybe you should split this out into multiple calls (off the top of my head so excuse any errors)

$maxEnemies = 10;
$enemiesSpawned = 0;

function spawnEnemy()
{
  if ($enemiesSpawned < $maxEnemies)
  {
    createEnemy();
    $enemiesSpawned++;
    // spawn next enemy in 2 seconds
    schedule(2000, 0, "spawnEnemy()");     
  }
  else
  {
      $player.setVisible( false );
      playerMap.pop();
      showLevelEnd();
  }
}

That would spawn one enemy when you first call the function, then another enemy every 2 seconds. then 2 seconds after the last enemy was spawned the end level will execute. You could add additional checks/schedules to only end the level when all enemies have been destroyed (depending on how your game works) in there as well.

Torque 3D Owner Stephen Zepp
#3
03/24/2005 (6:05 am)
Greg's nudging you in the right direction--your main problem is that you are probably not fully aware yet of the simulation itself, and how it relates to scripting. For example, it appears based on your logic flow that what you want is:

A) Spawn a new enemy every 2 seconds.
B) If the player is still alive when the last enemy is spawned, end the level.

Greg shows one way of doing it--remove the structure of the for loop itself, since a for loop is "all at once", and implement the logic based on how schedule works instead. Another way would be to keep the for loop in place, but not increment your $enemiesSpawned in this loop, but in the createEnemy() function. That way, you are only incrementing the number (just like in Greg's example) when the actual spawning occurs, not at the time of it being scheduled to occur.