Unity how to check for double key presses.

Unity Engine
1

Hi everyone glad you are here any help will be appreciated any how lets get to my questions I saw a lot of ways to do this in the forums but I want to make sure this will fit in my game and ideas for it aswell.

Currently I want to make a way to check your magazine to see how many rounds are in your gun by pressing a key twice preferably the R key. My weapon script has a reload function that uses the R key as well which is why I wanted to go with pressing R twice to check the magazine any ideas on how to do this? Any help will be appreciated here is my current code for reloading which I presume will have to be changed since I will be pressing R twice and make it think that I am not pressing it once if that makes sense.

    IEnumerator Reload()
    {
        if(!IsReloading & currentAmmo_ != MagazineSize)
        {
            print("Reloading");
            CanShoot = false;
            IsReloading = true;
            yield return new WaitForSeconds(ReloadTime);
            currentAmmo_ = MagazineSize;
            CanShoot = true;
            IsReloading = false;
        }
    }

Here is my Update void where I check for inputs.

    public void Update()
    {
        if (IsAutomatic)
        {
            isfiring = Input.GetMouseButton(0);
        }
        else
        {
            isfiring = Input.GetMouseButtonDown(0);
        }

        if (isfiring & !IsReloading & CanShoot & currentAmmo_ > 0)
        {
            StartCoroutine("Shoot");
            print("Called fire");
        }

        if (Input.GetKeyDown(KeyCode.R))
        {
            StartCoroutine("Reload");
        }

    }
2

I’m confused how you want to handle the first press of the R key. Do you want the reload to start, and then on the second press within a certain time frame it does the mag ammo check mid-reload? Or do you want a reload from the first press to wait until it is no longer possible for a second press to result in the ammo check (a check for double R has timed out), and only then start the reload?

3

Hi!
What I would do is storing a variable that defines the delay required to consider it a double-press, instead of two single presses.
Something like 0.25f could do it.
Then, I would go for something like this:

float delayBetweenPresses = 0.25f;
bool pressedFirstTime = false;
float lastPressedTime;

void Update()
{
    if (Input.GetKeyDown(KeyCode.R))
    {
        if (pressedFirstTime) // we've already pressed the button a first time, we check if the 2nd time is fast enough to be considered a double-press
        {
            bool isDoublePress = Time.time - lastPressedTime <= delayBetweenPresses;
  
            if (isDoublePress)
            {
                Debug.Log("check for ammo");
                pressedFirstTime = false;
            }
        }
        else // we've not already pressed the button a first time
        {
            pressedFirstTime = true; // we tell this is the first time
        }
 
        lastPressedTime = Time.time;
    }
 
    if (pressedFirstTime && Time.time - lastPressedTime > delayBetweenPresses) // we're waiting for a 2nd key press but we've reached the delay, we can't consider it a double press anymore
    {
        // note that by checking first for pressedFirstTime in the condition above, we make the program skip the next part of the condition if it's not true,
        // thus we're avoiding the "heavy computation" (the substraction and comparison) most of the time.
        // we're also making sure we've pressed the key a first time before doing the computation, which avoids doing the computation while lastPressedTime is still uninitialized
        Debug.Log("reload");
        pressedFirstTime = false;
    }
}

Of course, this will ONLY process the single key press after the said delay, so keeping a short delay is better:

  • to ensure the user really wanted to do a double press, and not just two single presses in a short period of time.
  • to process the single key press faster (since we can only process it after making sure it can’t be a double press)

Please note that this code actually answers the 2nd hypothesis of @Joe-Censored , which is the one I assumed was the one you wanted.

I hope the code is clear enough! If not, don’t hesitate to ask :slight_smile:

P.S: as a side note, please don’t use StartCoroutine with the name of your coroutine. It is a very bad practice because you’ll have a bunch of errors if ever you rename your coroutine later. Instead of StartCoroutine("MyCoroutine"), prefer: StartCoroutine(MyCoroutine()).
This is also better because you can use arguments just like with a regular function: StartCoroutine(MyCoroutine(arg1, arg2)).

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4

Hey sorry If I said it wrong basicly if you press R and don’t press again for example within .50ms then it will reload, but if you press again it will check the magazine and not reload.

5

Thank you very much this is the exact answer I was looking for and thanks for the tip with my Coroutines I have recently started and am trying to improve have a good rest of your day.

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