How do I make instances of enemies spawn after every three keypress movements?

Question

I am making a game, where two zombies will spawn after every three moves my character makes. The problem is that I have no idea how to do this.

I have my character moving correctly, in each key press event, so I want the game to count each time one of these events are triggered, and perform the action after every third trigger. Perhaps I need a global variable/counter that can count these events?

How do I make instances of enemies spawn after every three keypress movements?

Answer 1

Here is some pseudocode:

If keypress do
    KeyPressCounter++
End
If KeyPressCounter%3 == 0 do
    Action ()
End

This preforms a modulo operation which will detect numbers divisible by 3.

Answer 2

If you want to create this type of event, I suggest this :

If your character moves with the directional keys, then create four Keypress event : one for each key (Up, Down, Right, Left). Create a variable in Create event, and increment this variable in the four event previously created. Then, in the Step event, check if the variable is equal at 3. If yes, do your action and set the variable at 0. If not, do nothing.

Here what it looks in code :

Create event :

number_key_pressed=0;

Key press left event :

number_key_pressed+=1;

Key press right event :

number_key_pressed+=1;

Key press up event :

number_key_pressed+=1;

Key press down event :

number_key_pressed+=1;

Step event :

if(number_key_pressed==3)
{action();
number_key_pressed=0;}