# Action button: only true once per press

I'm using SFML2.0 and am trying to make a wrapper class for my controller/joystick. I read all the input data from my controller and send it off to my controllable object.

I want to have two types of buttons per button press, one that is continues(true false state ) and one that is an action and is set to false after the next frame update.

Here is an example of how I set my button A to true or false with the SFML api. Whereas data is my struct of buttons, and A holds my true/false state every update.

data.A = sf::Joystick::isButtonPressed(i,st::input::A);


But I've also added "data.actionA" which represents the one time action state.

Basically what I want is for actionA to be set false after the update its been set to true. I'm trying to keep track of the previous state. But I seem to fall into this loop where it toggles between true and false every update.

Anyone an idea?

Here's some pseudo code for you to try

// This here is a global variable.
...
bool wasButtonPressed = false;
...

// This here is your function.
...
bool isButtonPressed = sf::Joystick::isButtonPressed(i,st::input::A);

// Check if the key was pressed since last frame, aka KeyPressed.
if(isButtonPressed && !wasButtonPressed)
someFunction();

// Check if the key was held since last frame, aka KeyHeld.
if(isButtonPressed && wasButtonPressed)
someFunction();

// Check if the key was released since last frame, aka KeyReleased.
if(!isButtonPressed && wasButtonPressed)
someFunction();

wasButtonPressed = isButtonPressed;
...


We store the previous state, so we know how the key has changed since the last frame.

• Yes I already solved it myself ( see edit ). I was already keeping track of previous states. I was overthinking it. – Sidar Jun 20 '12 at 16:08

My solution:

data.actionA = data.A = sf::Joystick::isButtonPressed(i,st::input::A);
if(prev.A) data.actionA = false;


First I always set the actionA to the value of the button state. Then I check if the previous state of A is true. If so we negate the value.