Question

Here is the gameplay. There is three condition.

The player step on a Switch-Tile and it became false.

1) When the Enemy step on it (trapped) AND the player step on it too, the Enemy will be destroyed.

2) But when the Enemy step on it AND the player DIDN’T step on it too, the Enemy will be escaped.

3) If the Switch-Tile condition is true then nothing happened. The effect is activated when the Switch tile is false (player step on the Switch-Tile).

Because there are a lot of Enemy and a lot of Switch-Tile, I have to use foreach loop.

The problem is after the Enemy is ESCAPED (case 2) and step on another Switch-Tile again, nothing happened to the enemy!

I didn’t know what’s wrong. The effect should be the same, but the Enemy pass the Switch tile like nothing happened (They should be trapped)

Can someone tell me what’s wrong?

Here is the code :

public static void switchUpdate(GameTime gameTime)
        {
            foreach (SwitchTile switch in switchTiles)
            {
                foreach (Enemy enemy in EnemyManager.Enemies)
                {
                    if (switch.Active == false)
                    {                    
                        if (!enemy.Destroyed)
                        {                                
                            if (switch.IsCircleColliding(enemy.EnemyBase.WorldCenter,
                                enemy.EnemyBase.CollisionRadius))
                            {                                    
                                enemy.EnemySpeed = 10; //reducing Enemy Speed if it enemy is step on the Tile (for about two seconds)
                                enemy.Trapped = true;
                                float elapsed = (float)gameTime.ElapsedGameTime.Milliseconds;
                                moveCounter += elapsed;
                                if (moveCounter> minMoveTime)
                                {
//After two seconds, if the player didn't step on Switch-Tile.
//The Enemy escaped and its speed back to normal
                                    enemy.EnemySpeed = 60f;
                                    enemy.Trapped = false;
                                }
                            }
                        }
                    }

                    else if (switch.Active == true && enemy.Trapped == true
                        && switch.IsCircleColliding(enemy.EnemyBase.WorldCenter,
                                enemy.EnemyBase.CollisionRadius)
                        )
                    {
//When the Player step on Switch-Tile and 
//there is an enemy too on this tile which was trapped = Destroy Enemy  

                        enemy.Destroyed = true;                            
                    }
                }

            }
        }

Answer 1

           else if (switch.Active == true && enemy.Trapped == true
                && switch.IsCircleColliding(enemy.EnemyBase.WorldCenter,
                        enemy.EnemyBase.CollisionRadius)
                )
            {
                //When the Player step on Switch-Tile and 
                //there is an enemy too on this tile which was trapped = Destroy Enemy  

                enemy.Destroyed = true;                            
            }

This code will never be true since you set whether the enemy is trapped or not only if the switch is not active. Once you set it to true you should really break out the loop and then test again to see whether you should destroy the enemy or not.

Rethink the logic you want to do, and ensure that at each stage you can gain access to the correct information for the enemy etc.

P.S You do NOT need to use a foreach loop. You could easily use a for loop and iterate over the container or if you were really sadistic you could simple hardcode for every enemy yourself. Foreach loops are simply one way to solve this kind of issue, just because they can be used, doesnt mean you need to use them 😉