GameMaker has a number of dedicated actions that can be used to detect both analog and digital controls from multiple connected game pads. These actions require you to specify a gamepad index value, which is a number (counting from 0) that represents the gamepad being selected. Note that when a gamepad is plugged in to your device (or it is removed) then an asynchronous System Event is triggered (however to deal with this you may need to use code).
The gamepad "slots" are indexed from 0 with slots 0 - 3 inclusive being only for Xinput gamepads, ie: Xbox360 controllers and compatibles. However, you can also check slots 4 - 11 inclusive for DirectInput gamepads, which means you can detect many other models of controller when connected through these slots.
When working with the gamepad actions, input can come from axes, buttons or hats, which GameMaker will assign to the following built-in constants (note that "hats" are generally only detected on non-standard controllers):
| Gamepad Button Constant | |
|---|---|
| Constant | Description |
| gp_face1 | Top button 1 (this maps to the "A" on an Xbox controller and the cross on a PS controller) |
| gp_face2 | Top button 2 (this maps to the "B" on an Xbox controller and the circle on a PS controller) |
| gp_face3 | Top button 3 (this maps to the "X" on an Xbox controller and the square on a PS controller) |
| gp_face4 | Top button 4 (this maps to the "Y" on an Xbox controller and the triangle on a PS controller) |
| gp_shoulderl | Left shoulder button |
| gp_shoulderlb | Left shoulder trigger |
| gp_shoulderr | Right shoulder button |
| gp_shoulderrb | Right shoulder trigger |
| gp_select | The select button (on a PS controller, this triggers when you press the touchpad down) |
| gp_start | The start button (this is the "options" button on a PS controller) |
| gp_stickl | The left stick pressed (as a button) |
| gp_stickr | The right stick pressed (as a button) |
| gp_padu | D-pad up |
| gp_padd | D-pad down |
| gp_padl | D-pad left |
| gp_padr | D-pad right |
| gp_home | The "home" button on Switch controllers, and the PS/XBOX logo buttons on some controllers |
| gp_touchpadbutton | The touchpad button on a PS controller |
| gp_paddler | Upper or primary paddle, under your right hand (e.g. Xbox Elite paddle P1) |
| gp_paddlel | Upper or primary paddle, under your left hand (e.g. Xbox Elite paddle P3) |
| gp_paddlerb | Lower or secondary paddle, under your right hand (e.g. Xbox Elite paddle P2) |
| gp_paddlelb | Lower or secondary paddle, under your left hand (e.g. Xbox Elite paddle P4) |
| gp_extra1 | An extra button that may be mapped to anything |
| gp_extra2 | An extra button that may be mapped to anything |
| gp_extra3 | An extra button that may be mapped to anything |
| gp_extra4 | An extra button that may be mapped to anything |
| gp_extra5 | An extra button that may be mapped to anything |
| gp_extra6 | An extra button that may be mapped to anything |
To better understand exactly what part of the controller each constant represents, you can refer to the following image of a standard Xinput gamepad:
The available gamepad actions are all listed below:
 | Get Gamepad Axis |
 | Get Gamepad Trigger |
 | Get Gamepad Count |
 | Get Gamepad Connected |
 | Set Gamepad Axis Deadzone |
 | Set Gamepad Button Threshold |
 | If Gamepad Button Pressed |
 | If Gamepad Button Down |
 | If Gamepad Button Released |
The following list shows current compatibility across the platforms (note that this will change with future updates):
sudo apt-get install jstest-gtk
sudo apt-get install joystick.