Controller input

Author(s): catinsurance
Tags:

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Game controllers can complicate detecting arbitrary button presses.

Controller detection

Controllers can easily be detected by reading the ControllerIndex property of the player. If it is above 0, then the player must be using a controller, as 0 is always the ControllerIndex of the keyboard.

local player = Isaac.GetPlayer(0)
print(player.ControllerIndex)

Controllers and Input.IsButtonTriggered/Pressed()

Controllers can be detected by Input.IsButtonTriggered() and Input.IsButtonPressed(), but not without some caveats.

Firstly, controller inputs don't have a value in the Keyboard enum, but they do have a number which corresponds to what button you're pressing.

local controllerButtons = {
    DPAD_LEFT = 0,
    DPAD_RIGHT = 1,
    DPAD_UP = 2,
    DPAD_DOWN = 3,
    ACTION_DOWN = 4,
    ACTION_RIGHT = 5,
    ACTION_LEFT = 6,
    ACTION_UP = 7,
    BUMPER_LEFT = 8,
    TRIGGER_LEFT = 9,
    STICK_LEFT = 10,
    BUMPER_RIGHT = 11,
    TRIGGER_RIGHT = 12,
    STICK_RIGHT = 13,
    SELECT = 14,
    START = 15
}

Secondly, controllers trigger multiple values at once. Pressing a button on the controller will trigger 4 different values in the Keyboard enumerator. This can cause complications for detecting keyboard input, because a controller can trigger a value that you're not expecting.

Reproduction code

local mod = RegisterMod("Input test mod", 1)

mod:AddCallback(ModCallbacks.MC_POST_RENDER, function ()
    for i, v in pairs(Keyboard) do
        if Input.IsButtonTriggered(v, Isaac.GetPlayer().ControllerIndex) then
            print("Enum", i, "pressed with value", v, "and with a true value of", v % 32)
        end
    end
end)

To detect if a keyboard button was triggered by a controller, you can modulo the input by 32. This will always return the correct value of the button pressed.

local function safeKeyboardTriggered(key, controllerIndex)
    return Input.IsButtonTriggered(key, controllerIndex) and not Input.IsButtonTriggered(key % 32, controllerIndex)
end

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