Python mini RPG enemy movement. (how to have two infinite loops running at the same time)

Question

I have a problem with my RPG.

I want enemies to wander randomly. So I put:

enx_speed = random.randint(-2, 2) 
eny_speed = random.randint(-2, 2) 

in the main loop (while true:). However, that loops every 20 milliseconds (it's what I use to redraw, find key presses, etc).

How can I have two infinite loops running at the same time with different loop times?

Answer 1

Don't know python, but here is a basic arbitrary-language example.

You should only have one game loop that updates all other entities. You can determine how much time has passed between each running of the loop and pass that information on to the entities who can use this information. For Example:

main() {
    lastSystemTime = currentSystemTime;
    while (true) {
         //Time passed since last loop in milliseconds
         int delta = currentSystemTime - lastSystemTime;
         lastSystemTime = currentSystemTime;

         //Loop through all interested parties and update them with time passed
         for all sub-entities {
             entity.update(delta);
         }
    }
}

Then in the entity

constant int WAIT_TIME = 200; //200 milliseconds to wait after actions performed
int timer = 0; //How much time to wait before performing actions

update(int delta) {
    if (timer <= 0) {
        //Perform the actions, then set the wait timer.
        doStuff();
        timer += WAIT_TIME; // Add the wait time to the timer
    }
    else {
        timer -= delta; //Decrease current time to wait by how much time has passed
    }
}

Answer 2

You only need one infinite loop running very fast to do what you're after. Inside the loop you calculate time elapsed since last run. If it's greater than X, then you call function1. If it's greater than Y, then you call function2.

Answer 3

I managed to solve this myself and the method I used was probably not the best but it was really really easy.

First I define "enloop" outside of the main loop.

enloop = 0 

Then inside the loop every time the loop runs:

if enloop < 10:
    enloop = enloop + 1
else:
enloop = 0

And later also in the loop:

if enloop == 10:
    enx_speed = random.randint(-2, 2) 
    eny_speed = random.randint(-2, 2)

Thanks for responding and let me know if this is wrong somehow.