If NOT pressing 2 keys simultaneously, do this

[Dannyinformal]

Hey lads,

So I'm making a small Metroidvania game for kicks and laughs. I made a boost/sprint key modifier (shift) which bugs out. I was wondering if you guys could help me out. This is what happens:

1. You start with 20 boost power
2. When you press right + boost you dash and the boost power gradually decreases
3. Sub 20, it slowly regenerates

In point 3 lies the problem; the boost power regenerates, but stops regenerating the moment i press right, een without pressing the modifier. This is my code:

if obj_gegevens.boost > 0 && keyboard_check (vk_right) && keyboard_check (vk_lshift) //when you press shift and right DASH
{
x += 20;
image_speed = 1;
obj_gegevens.boost -=1;
}

if obj_gegevens.boost < 20 && !keyboard_check (vk_right) && !keyboard_check (vk_lshift) //when you DON'T press shift and right, regenerate
{
obj_gegevens.boost +=0.2;
}

Thanks for your help lads!

 

[Simon Gust]

Try this

var boosting = false;
if (keyboard_check (vk_lshift))
{
    var side = keyboard_check(vk_right) - keyboard_check(vk_left);
    if (side != 0)
    {
        boosting = true;
        if (obj_gegevens.boost > 0)
        {
            x += 20 * side;
            image_speed = 1;
            obj_gegevens.boost = max(obj_gegevens.boost - 1.0, 0);
        }
    }
}

if (!boosting)
{
    obj_gegevens.boost = min(obj_gegevens.boost + 0.2, 20);
}

 

[Dannyinformal]

Hey Simon,

Thank you for your quick reply!

The code works but I have to admit I have no idea what's actually happening in it. Would you mind adding annotations explaining the syntax per sentence?

Especially this:

var side = keyboard_check(vk_right) - keyboard_check(vk_left);

Also, is there a particular reason you write "var" in front of a new variable? It also works without, what's the difference?

What's happening there, exactly? You create a variable "side", right and you assign vk_right minus vk_left to it?

I feel kinda stupid using a piece of code without actualy understanding what's written.

Thanks again for all your help and your patience!

 

[Simon Gust]

Sure.

First though, to why your original code didn't work.

if obj_gegevens.boost < 20 && !keyboard_check (vk_right) && !keyboard_check (vk_lshift)

This statement requires that the right-key isn't pressed under any circumstances even if you're not pressing shift.
But you only want it to not rgenerate when both keys are pressed together. You need to bundle the statements ->

if obj_gegevens.boost < 20 && (!keyboard_check (vk_right) && !keyboard_check (vk_lshift))

Now to my code.
First, I set a variable "boosting" to false. (This is my set-unset statement)
It controls the regeneration of the boost. Boost can only regenerate when you're not "boosting".

Then, I first check for the "enable boost" key.
Then I calculate the variable "side". Side is a smart variable.
It turns 1 if you only press the right key.
It turns -1 if you only press the left key.
It turns 0 if you either press no key or both keys at the same time.

This works because keyboard_check() returns either 0 or 1 (false or true).
pressing right but not left -> side = (1) - (0)
pressing left but not right -> side = (0) - (1)
pressing both -> side = (1) - (1)
pressing neither -> side = (0) - (0)

Then, I check if side is not 0 before checking if you have boost at all.
The reason for this is so that boost doesn't regenerate while trying to boost.

And finally I increase x by 20 by whichever side you're going. (another use of the side variable),

To change the boost I use the min() and max().
to set a maximum to a variable, use min().

A = min(A + 1, maxium_of_A);

to set a minimum to a variable, use max().

A = max(A - 1, minimum_of_A);

 

[Dannyinformal]

Sure.

First though, to why your original code didn't work.

if obj_gegevens.boost < 20 && !keyboard_check (vk_right) && !keyboard_check (vk_lshift)

This statement requires that the right-key isn't pressed under any circumstances even if you're not pressing shift.
But you only want it to not rgenerate when both keys are pressed together. You need to bundle the statements ->

if obj_gegevens.boost < 20 && (!keyboard_check (vk_right) && !keyboard_check (vk_lshift))

Now to my code.
First, I set a variable "boosting" to false. (This is my set-unset statement)
It controls the regeneration of the boost. Boost can only regenerate when you're not "boosting".

Then, I first check for the "enable boost" key.
Then I calculate the variable "side". Side is a smart variable.
It turns 1 if you only press the right key.
It turns -1 if you only press the left key.
It turns 0 if you either press no key or both keys at the same time.

This works because keyboard_check() returns either 0 or 1 (false or true).
pressing right but not left -> side = (1) - (0)
pressing left but not right -> side = (0) - (1)
pressing both -> side = (1) - (1)
pressing neither -> side = (0) - (0)

Then, I check if side is not 0 before checking if you have boost at all.
The reason for this is so that boost doesn't regenerate while trying to boost.

And finally I increase x by 20 by whichever side you're going. (another use of the side variable),

To change the boost I use the min() and max().
to set a maximum to a variable, use min().

A = min(A + 1, maxium_of_A);

to set a minimum to a variable, use max().

A = max(A - 1, minimum_of_A);

Super clear Simon! Thank's for taking the time to explain this in detail, you're the best!

 

[TheouAegis]

C && (!A && !B) is the exact same thing as C && !A && !B. What you need to do is move the !'s outside the parentheses.

if !( keyboard_check(vk_right) && keyboard_check(vk_lshift) )

 

[Simon Gust]

C && (!A && !B) is the exact same thing as C && !A && !B. What you need to do is move the !'s outside the parentheses.

if !( keyboard_check(vk_right) && keyboard_check(vk_lshift) )

right, thanks.

EDIT:
Good thing that I don't let myself do these kind of statements or I would have bugs all over my code.