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Joysticks - How can I get more than one working
devo_au
Member #15,282
August 2013

Hey,

I'm making a game that has 2 or more players using gamepads.
I can't find an event

ALLEGRO_EVENT ev; 
if (ev.type == ALLEGRO_EVENT_JOYSTICK_BUTTON_DOWN)
{}

that allows me to determine
what gamepad the button presses are occurring from.

If I use states

//im using all the init stuff correctly, 
//this is just a snippit to explain what im up to
ALLEGRO_JOYSTICK_STATE joyState1;
al_get_joystick_state(joy1, &joyState1);
cout << joyState1.button << "\n";

I get the same output from all the main buttons (ie. 00E9A5D8)
but for some reason it can read select and the triggers.

Hope someone can help - Thanks Dev

it wasn't me, it was other kids

RPG Hacker
Member #12,492
January 2011
avatar

Have you iterated over all joysticks Allegro returns to you? Maybe it's polling some data from a weird device. Or maybe it's a driver issue of some sorts.

As for using ALLEGRO_EVENTs, this page has some more information for you:
Manual
Basically, once you detect a ALLEGRO_EVENT_JOYSTICK_AXIS, ALLEGRO_EVENT_JOYSTICK_BUTTON_DOWN or ALLEGRO_EVENT_JOYSTICK_BUTTON_UP event, you can check joystick.id to get the ID of the joystick. I'm not sure if ALLEGRO_EVENT already has a joystick field right away or if you need to cast it to another type, but I'd expect that it just uses a union internally and that it already has the joystick field, so you can just check that.

Or in other words: ev.joystick.id

Edgar Reynaldo
Member #8,592
May 2007
avatar

Yes, RPG Hacker is correct. Use ev.joystick.id to get the joystick id. And with joystick button events, use ev.joystick.button to get the button pressed.

As for al_get_joystick_state, you're not using it correctly. joystick_state.button is an array, not a bool value indicating whether a button was pressed. You need to access the specific button that you are asking for first :

for (int i = 0 ; i < al_get_num_joysticks() ; ++i) {
   ALLEGRO_JOYSTICK* joy = al_get_joystick(i);
   ALLEGRO_JOYSTICK_STATE joy_state;
   al_get_joystick_state(joy , &joy_state);
   for (int j = 0 ; j < al_get_joystick_num_buttons ; ++j) {
      if (joy_state.button[j]) {
         printf("Joystick number %d has button %d pressed.\n" , i , j);
      }
   }
}

devo_au
Member #15,282
August 2013

Awesome thank you for your replies..

RPG - I didn't know about ev.joystick.id. Iterating them. Hmmm...
Edgar - Ah! that hex number is an address of a array.

Thanks for that loop Edgar. So thats what RPG meant.
Plugged it in - problem solved. Just have to hook it
up to my players.

Cheers guys. You have helped me heaps.. Dev

it wasn't me, it was other kids

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