IEnumerator IntervaledTick()
{
//this is of fundamental importance: Never create implementors as Monobehaviour just to hold
//data (especially if read only data). Data should always been retrieved through a service layer
//regardless the data source.
//The benefits are numerous, including the fact that changing data source would require
//only changing the service code. In this simple example I am not using a Service Layer
//but you can see the point.
//Also note that I am loading the data only once per application run, outside the
//main loop. You can always exploit this pattern when you know that the data you need
//to use will never change
var enemiestoSpawny = ReadEnemySpawningDataServiceRequest();
var enemyAttackDatay = ReadEnemyAttackDataServiceRequest();
yield return(enemiestoSpawny);
yield return(enemyAttackDatay);
var enemiestoSpawn = enemiestoSpawny.Current;
var enemyAttackData = enemyAttackDatay.Current;
var spawningTimes = new float[enemiestoSpawn.Length];
for (var i = enemiestoSpawn.Length - 1; i >= 0 && _numberOfEnemyToSpawn > 0; --i)
{
spawningTimes[i] = enemiestoSpawn[i].enemySpawnData.spawnTime;
}
_enemyFactory.Preallocate();
while (true)
{
//Svelto.Tasks can yield Unity YieldInstructions but this comes with a performance hit
//so the fastest solution is always to use custom enumerators. To be honest the hit is minimal
//but it's better to not abuse it.
yield return(_waitForSecondsEnumerator);
//cycle around the enemies to spawn and check if it can be spawned
for (var i = enemiestoSpawn.Length - 1; i >= 0 && _numberOfEnemyToSpawn > 0; --i)
{
if (spawningTimes[i] <= 0.0f)
{
var spawnData = enemiestoSpawn[i];
//In this example every kind of enemy generates the same list of EntityViews
//therefore I always use the same EntityDescriptor. However if the
//different enemies had to create different EntityViews for different
//engines, this would have been a good example where EntityDescriptorHolder
//could have been used to exploit the the kind of polymorphism explained
//in my articles.
var enemyAttackStruct = new EnemyAttackStruct
{
attackDamage = enemyAttackData[i].enemyAttackData.attackDamage,
timeBetweenAttack = enemyAttackData[i].enemyAttackData.timeBetweenAttacks
};
//has got a compatible entity previously disabled and can be reused?
//Note, pooling make sense only for Entities that use implementors.
//A pure struct based entity doesn't need pooling because it never allocates.
//to simplify the logic, we use a recycle group for each entity type
var fromGroupId = ECSGroups.EnemiesToRecycleGroups + (uint)spawnData.enemySpawnData.targetType;
if (entitiesDB.HasAny <EnemyEntityViewStruct>(fromGroupId))
{
ReuseEnemy(fromGroupId, spawnData);
}
else
{
yield return(_enemyFactory.Build(spawnData.enemySpawnData, enemyAttackStruct));
}
spawningTimes[i] = spawnData.enemySpawnData.spawnTime;
_numberOfEnemyToSpawn--;
}
spawningTimes[i] -= SECONDS_BETWEEN_SPAWNS;
}
}
}