mmk.gamepad

MaulingMonkey's typescript gamepad API for consistent cross-browser and cross-gamepad binding, polling for input, etc.

• GitHub: github.com/MaulingMonkey/mmk.gamepad
• Demo: maulingmonkey.com/mmk.gamepad/demo/
• Docs: maulingmonkey.com/mmk.gamepad/docs/
• NPM: @maulingmonkey/gamepad
• License: Apache 2.0

What? Why?

The vanilla browser gamepad APIs are unusable without a lot work, except for maybe if you stick to vanilla Microsoft 360/XB1 gamepads.

1. Noop fallbacks for unsupported browsers so you don't have to do your own feature testing.
2. Edge has conflicting gamepad browser navigation that needs to be disabled, if you don't want basic input like pressing (B) to navigate away.
3. Many browsers poorly standardize gamepads. Even ignoring outright buggy "standard" layout gamepads, I've seen dpads exposed as -1/8..+1 axises, int -> float bitcasts of accelerometer data, gamepads that start initialized to non-resting states... testing hardware you don't have is hard, I guess.
4. Basic gamepad APIs don't handle basic things like deadzone functionality, events (although Edge has some keydown events for gamepads)

Browser Support

OS	Browser	Max Gamepads	API(s)	Notes
Windows 7	Opera 44	4	XInput or RawInput
Windows 7	Chrome 57	4	XInput or RawInput
Windows 7	FireFox 53	5+	XInput or RawInput
Windows 10	Edge	4?	Only XInput?	[4] [5]
Windows 7	IE 11	0	No gamepad API [1]	!isSupported [4]
Windows 7	IE 8	XXX [2]	No gamepad API	Compatability bugs
Ubuntu 18.04 LTS	Chromium 65	0	No gamepad API [1]	"isSupported" lies [3]
Ubuntu 18.04 LTS	Chrome 66	4+	Unknown
Ubuntu 18.04 LTS	FireFox 59	4+	Unknown

1. All mmk.gamepad functions should still "work" as if there were no gamepads connected.
2. This browser may still have compatability bugs even providing the "no gamepads" interface.
3. This browser implements a gamepad API, but no gamepads work.
4. You may need to specify <meta http-equiv="X-UA-Compatible" content="IE=9" /> or better to avoid JS errors.
5. Edge has some built-in gamepad navigation behavior. mmk.gamepad will disable this by default.

Gamepad support

OS	Gamepad	Chrome	Opera	FireFox	Edge	Notes
Windows	Xbox 360	OK	OK	OK [1]	OK
Windows	Xbox One	OK [1]	OK [1]	OK [1]	OK [1]
Windows	DualShock 4 (Micro-USB)	OK	OK	No DPad		No touch/gyros
Windows	DualShock 4 (Wireless)	OK	OK	No DPad		No touch/gyros
Windows	DualShock 3 (Mini-USB)	OK	OK	No DPad		Needs PS Now
Windows	Nintendo Switch Pro Cont	OK	OK	Dead
Windows	Saitek X52	No Scroll	No Scroll	No HAT 1		[2]

1. This gamepad displays an incorrect or generic name which we cannot work around (e.g. "Xbox 360 Controller" for XB1 controllers, or "xinput")
2. This has a custom .mapping !== "standard"

OS	Gamepad	Chrome [4]	FireFox	Notes
Ubuntu	Xbox 360	OK	OK
Ubuntu	Xbox One	OK	OK
Ubuntu	DualShock 4 (Micro-USB)	OK [5]	OK	No gyros, bad init [6], touchpad is mouse
Ubuntu	DualShock 4 (Wireless)	OK [5]	OK	No gyros, bad init [6], touchpad is mouse
Ubuntu	DualShock 3 (Mini-USB)	OK	OK	No gyros

4. Not Chromium - which still defines the gamepad API, but doesn't appear to actually export info about connected gamepads even when Chrome will on the same system.

5. Note that the baseline gamepad API lies about this gamepad being in the standard layout already in Chrome 66 on Ubuntu 18.04 LTS. tryRemapStdLayout will fix these to use the correct layout anyways.

6. Some triggers/axises of this gamepad currently misinitialize to non-zero values (e.g. -1, 0.5), although they'll correct themselves after some use. Could be worked around with some more stateful mapping (e.g. treating known bad values as 0.0 until the right stick / triggers are sufficiently exercised.)

Basic API

See demo/demo.ts

// In case you want to display a hint to switch browsers ;)
if (!mmk.gamepad.isSupported()) console.warn("Gamepads not available in this browser");

// The rough equivalent of navigator.getGamepads(), with fallbacks.
var gamepads = mmk.gamepad.getRawGamepads() // Can return undefined elements (for e.g. disconnected controllers)

var snapshot = mmk.gamepad.cloneGamepads(gamepads); // Deep copy of basic fields
snapshot[0]  = mmk.gamepad.cloneGamepad(snapshot[0]); // Hey why not

// Works despite the lack of "connectedgamepad" and "disconnectedgamepad" events:
mmk.gamepad.addRawConnectedListener   ( function(gamepad) { console.log("Connected gamepad:",   gamepad); } );
mmk.gamepad.addRawDisconnectedListener( function(gamepad) { console.log("Disconnected gamepad:", gamepad); } );
// (note that addRawConnectedListener will immediately invoke your callback on already connected gamepads!)

var standard = mmk.gamepad.tryRemapStdLayout(snapshot[0]);
if (standard) { console.assert(standard.mapping === "standard"); } // Well, that was easy!
else          { ... } // Fallback to non-standard mapping prompts etc...

Installation

Via npm

• Grab NPM via node.js
• Install per project

  npm i @maulingmonkey/gamepad

Contribution Notes

Adding New Devices

Negative values should always be left/up/forward/counterclockwise, with positive values corresponding to their opposites (right/down/backwards/clockwise). This might be unintuitive for some axises on an individual basis (yes, joystick forward is negative!), but this has a couple of advantages. Firstly, it keeps everything nice and consistent for remapping purpouses (thumbstick up is negative too, and you might want to use that as your throttle!) Secondly, it reduces the importance of properly categorizing your axises ("should I map this as a throttle, or as a slider?") as this won't impact how the values are actually mapped.

Additionally, axises should almost always span the entire [-1..+1] range. While you might want to remap this to [0..+1] in your game (possibly with a button for reversing), consistency at the lowest layer will make such remaps more straightforward. The exception to this would be any unidirectional, spring-loaded axises - any spring-loaded resting position should be 0. It's possible such axises should be considered buttons instead - e.g. gamepad triggers are considered buttons in the "standard" mapping.

Axis (-1..+1)	Min (-)	Max (+)	Notes
Thumbstick X	"left"	"right"
Thumbstick Y	"up"	"down"
Joystick X	"left"	"right"
Joystick Y	"forward"	"backward"
Joystick Twist	"ccw"	"cw"
Throttle	"forward"	"backward"	Forward being negative may be suprising, but keeps consistent with thumbsticks.
Mouse X	"left"	"right"
Mouse Y	"up"	"down"

Buttons (0..+1)	Notes
Trigger	This includes analog triggers like the "standard" gamepad.
DPad Up/Down/L/R	Digital direction pads should be treated as 4 buttons, not axises.
HAT Up/Down/L/R	Digital HATs, like direction pads, should be treated as 4 buttons, not axises.