Twilight's Call: Tower Defence is a project I made to try and get used to the Unreal Game Engine while reusing assets from Twilights Call's to quickly speed up development time.

Twilight's Call: Tower Defence> is a very basic Tower Defence game. You can place towers and when an enemy enters the Turrets range it fires a projectile to attack the enemy. When an enemy has incurred too much damage it will die and give the player more money to buy more turrets.

Turret Lock Calculation

Each Turret has an area around itself and when an enemy enters or leaves its collision radius it triggers the turret to recalulate. The calculation is handled inside the enemy class. Enemy keeps track of how close it is to the current waypoint based on distance and how much distance is there between every other waypoint.

                        

// returns the full distance from start to end
float AEnemy_Base::CalculateDistanceFromRemainingToEnd()
{
	
	TArray TempWaypoints = Waypoints;
	float TempDistance = 0;
	
// if there is less then two checkpoints remaining then we will return 0
	if(!TempWaypoints.IsValidIndex(0) ||!TempWaypoints.IsValidIndex(1) )
	{
		return 0;
	}


//Loop through each of the waypoints but remove one since we are incrementing above the List 
	for(int i = 0; i < TempWaypoints.Num() - 1;i++)
	{
		if(TempWaypoints.IsValidIndex(i + 1))
		{
//Calculating the Distance Between the current waypoint and the next 
			TempDistance +=  FVector::Dist(TempWaypoints[i], TempWaypoints[i + 1]);
		}
	}
	
	return TempDistance;
}

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//Used when we have reached the current checkpoint and we are asking for the next one 
void AEnemy_Base::GoToNextWaypoint()
{
//If there are no waypoints left the enemy has gotten to the goal


	if(Waypoints.Num() == 0)
	{
		EnemyGotToGoal();
		return;
	}


//Calculating the distance between all the waypoints remaining
	DistanceInAllRemainingWaypoints = CalculateDistanceFromRemainingToEnd();
	
//Attaching waypoint
	CurrentWaypoint = Waypoints[0];
	Waypoints.RemoveAt(0);

}


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// Called in update
public void AEnemy_Base::MoveToWaypoint(float aDeltaTime)
{
	DistanceToCurrentWaypoint = FVector::Dist(GetActorLocation(), GoToWaypoint);
	CurrentDistanceRemaining = DistanceToCurrentWaypoint + DistanceInAllRemainingWaypoints;
}


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// Inside the Turret, This is called every time someone enters or leaves the collision radius

void ATurret::CalculateClosestEnemy()
{
//If there is no enemy in range then exit the function
	if(!EnemyInRange.IsValidIndex(0))
	{
		return;
	}
	
	
//Setting the Default starting enemy for comparison

	AEnemy_Base* EnemyTemp = Cast(EnemyInRange[0]);
	
//If there is more then one enemy do the calculations
	
	if(EnemyInRange.Num() > 1)
	{
		for (int i = 0; i < EnemyInRange.Num(); i++)
		{
			
		
			AEnemy_Base* IterativeEnemy = Cast(EnemyInRange[i]);

//If the Waypoints are not initialize then continue the loop
			if(IterativeEnemy->WaypointsAreSet == false)
			{
				continue;
			}


//Getting the absolute value of the distances
			float EnemyA = abs(IterativeEnemy->DistanceLeftInLevel);
			float EnemyB = abs(EnemyTemp->DistanceLeftInLevel);


//Safety Check that if both values are 0 then something wrong is happening
			if(EnemyA == 0 || EnemyB == 0 )
			{
				continue;
			}
			
			
//Direct comparison between the two values the shortest distance will be swapped
			if(EnemyA < EnemyB )
			{
				EnemyTemp = IterativeEnemy;
			}
		}
	}
	
	
// The enemy that is furthest ahead will be selected.
	EnemyToAttack = EnemyTemp;
	
//Adding the enemy to a delegate that gets called when the enemy is killed
	EnemyToAttack->EnemyDeathEvent.AddDynamic(this, &ATurret::EnemyWasKilled);
}