pogp

Portable Open Game Protocol 0.0.19

Making games should feel like playing games.

Introducing the POG protocol

The POG Protocol defines language-neutral binary representations of Inputs and State.

This allows us to create a portable game loop that can be run in browser or any major game engine.

Portable

• browser - use wasm to prototype and playtest with hot reloading

• standalone / mobile / console - use ffi to bring your game loop into any game engine

• online multiplayer - run your game loop on any web server or exchange pogp binary input peer to peer

Open

• input representations are based on web standards

• state representations use open standards (WIP)

• games that adopt the protocol can benefit from shared solutions for common functionality

Game

• immersion during the development process is sacrosanct. making games feels like playing games.

• the POG protocol is designed to be zero-copy, zero-alloc per frame

• you can continue to use and benefit from all the great game making tools and rendering you use today for mobile, browser, standalone and console targets

Goals

The goal of the POG protocol is to help create better games for players, to make game development more accessible, and to reduce crunch.

The goal is for anyone familiar with basic software development to create a game using the protocol today, using the languages and tools they're already familiar with.

Web and app developers benefit from industry-wide adoption of open technology like the HTTP protocol and Linux.

Game developers have typically suffered from a more closed source mindset, with many shared solutions for crucial low-level problems locked behind paywalls or other privileged access.

I love games, and I believe that by embracing open standards and shared solutions across languages and game engines, there can be a better world for developers and players of games.

Code Example (typescript/browser)

import { GameLoop, MarshalInput, KeyboardSnapshot } from 'pogp';

const keyboard = new KeyboardSnapshot();
const heroElement = document.body.appendChild('div') as HTMLElement;

let state = {
	hero: { x: 0, y: 0 }
};

new GameLoop((frame, now, inputs) => {
	// read inputs from binary buffer
	keyboard.addInput(MarshalInput.decodeKeyboard(inputs));

	// run update loop
	if (keyboard.isKeyDown(Key.KeyD)) {
		state.hero.x += 10;
	} else if (keyboard.isKeyDown(Key.KeyA)) {
		state.hero.x -= 10;
	}

	// render to screen
	heroElement.style.transform = `translateX(${state.hero.x}px)`;
})

Interactive Examples

---

Pong

https://pogprotocol.com

Project Status

The Pog Protocol is in a pre-alpha state. The protocol itself is still being defined, and client libraries currently only exist for rust.

We are looking for domain experts to contribute to libraries for each major game engine and runtime environment.

If you are interested in contributing or adding an environment to the list, please open a github issue or drop me a line on discord nu11#1111 or neil at nullent.com

Path to 1.0

---

• Define state protocol

• Define rendering protocol

• Flesh out existing libraries

  • rust
  • typescript
  • unity c#

• Add client libraries

  • c++
  • modern c#

• Add online multiplayer demo

  • in browser
  • in a game engine

• Add engine demos beyond unity

  • unreal engine
  • godot
  • bevy

Client Libraries

---

Game Logic Client Libraries

language	dev environment	inputs	state	wasm support
c#	unity	@ns	@ns	n/a
c++	unreal	OPEN	OPEN	OPEN
rust	bevy	OPEN	OPEN	OPEN
c#	browser	OPEN	OPEN	OPEN
c++	browser	OPEN	OPEN	OPEN
rust	browser	@ns	@ns	@ns
typescript	browser	@ns	@ns	@ns

Rendering Client Libraries

language	framework	environment	status
c#	unity	pc/mac/mobile/console	OPEN
c++	unreal	pc/mac/mobile/console	OPEN
rust	bevy	pc/mac	OPEN
swift	xcode/autolayout	ios	OPEN
typescript	pixi.js	browser	@ns

Contributors:

@ns - @neilsarkar

Reference

---

Inputs

Inputs contain the state of the input at the current frame.

Whenever possible, representations are based on open standards.

Gamepad (a.k.a. Controller) Input

Touch Input

Mouse Input

Keyboard Input

Gamepad Input

Gamepad input represents what's commonly called a "Controller".

We extend the open standard https://developer.mozilla.org/en-US/docs/Web/API/Gamepad with a standard for generic positional identifiers.

JSON Schema | JSON Example

Binary Schema | Binary Example

Gamepad JSON Schema

type

• This will be an Input Type set to gamepad

id

• The Gamepad.id of the gamepad

vendorId

• The vendor id of the gamepad.

productId

• The product id of the gamepad.

vendorName

• A human readable name for the vendor, e.g. Nintendo, Microsoft, Sony etc

productName

• A human readable name for the product, e.g. Left joy-con, Xbox Series S, Dualshock 5

buttons

• An array of Button states
  • label
    • the text printed on the button, e.g. Triangle, A, ZR
  • value
    • int representing the percentage depressed with four digits of precision
  • touched
    • boolean representing whether button is touched
  • position
    • string enum representing button position , e.g. left-face-top, right-shoulder-front

axes

• An array of Axes states
  • hand
    • string enum representing hand intended to be used with joystick: left | right | unknown
  • value
    • an array of two signed longs representing the x and y position of the thumbstick

Gamepad JSON Example

{
	type: 'Gamepad',
	id: 'Stadia Controller rev. A (STANDARD GAMEPAD Vendor: 18d1 Product: 9400)'
	vendorName: "Google",
	productName: "Stadia",

	buttons: [
		{
			label: 'A',
			position: 'right-face-bottom',
			value: 100000 // 100%
		},
		{
			label: 'B',
			position: 'right-face-right',
			value: 500600 // 50.06%
		},
		{
			label: 'X',
			position: 'right-face-left',
			touched: true,
			value: 0
		},
		{
			label: 'Y',
			position: 'right-face-top',
			value: 0
		},
		{
			label: 'L1',
			position: 'left-shoulder-front',
			value: 0
		},
		{
			label: 'L2',
			position: 'left-shoulder-back',
			value: 0
		},
		// ...
	],
	axes: [
		{
			hand: 'left',
			value: [
				0n, // x-axis idle
				2147483647n // y-axis max up
			]
		},
		{
			hand: 'right',
			value: [
				-2147483647, // x-axis full left
				-2147483647  // y-axis full down
			]
		}
	],
}

Gamepad Binary Schema

data	example	type	index	length (bytes)
type	1	byte (Input Type)	0	1
buttons.length	12	uint16	1	2
axes.length	12	uint16	3	2
buttons	[Button, Button]	Button	5	69 * buttons.length
axes	[Axes, Axes]	Axes	5 + (69 * buttons.length)	129 * axes.length

Gamepad Button Binary Schema

data	example	type	index	length (bytes)
position	2	byte (ButtonPosition)	0	1
value	100000	uint32	1	4
label	"A"	string	5	64

Gamepad Axes Binary Schema

data	example	type	index	length (bytes)
hand	1	byte (Hand)	0	1
x	100000	int64	1	64
y	100000	int64	65	64

Keyboard Input

Keyboard keys are represented using the w3 standard, supporting standard 101, Korean, Brazilian and Japanese keyboards.

https://www.toptal.com/developers/keycode

https://www.w3.org/TR/uievents-code/#keyboard-mac

{
       type: "keyboard",
       keys: [
               27,
               65
       ]
}

data	type	byte index	bit index
Null	bool	0	0
ArrowDown	bool	0	1
ArrowLeft	bool	0	2
ArrowRight	bool	0	3
ArrowUp	bool	0	4
Backspace	bool	0	5
Tab	bool	0	6
CapsLock	bool	0	7
Enter	bool	1	0
ShiftLeft	bool	1	1
ShiftRight	bool	1	2
ControlLeft	bool	1	3
MetaLeft	bool	1	4
AltLeft	bool	1	5
Space	bool	1	6
AltRight	bool	1	7
MetaRight	bool	2	0
...	bool	...	...
IntlRo	bool	9	4

Touch Input (WIP)

{
	type: "touch",
	resolution: [0,0],
	fingers: [
		// there will always be at least one element
		{
			position: [0,0],
			pressure: 0
		}
	]
}

Mouse Input (WIP)

{
	type: "mouse",
	resolution: [1920, 1080],
	position: [100, 100],
	buttons: [
		{
			id: 'left',
			down: true
		},
		{
			id :'right',
			down: false
		},
	],
	wheels: [
		{
			id: 'scroll',
			delta: [0,20,0]
		}
	]
}

Custom (WIP)

{
	type: "custom",
	id: 'my-flightstick',
	fields: [
		{
			id: 'whammybar',
			values: [420,69]
		},
		{
			id: 'something',
			values: [0]
		}
	]
}

State (WIP)

Game state represents the state of the game. This is going to be custom for each game.

int is short for int32

{
	// this is the pog protocol major version
	pog: 0,
	// this is the pog protocol minor version
	pogMinorVersion: 1

	// these are the members of the state.
	fields: {
		// primitives
		timeLeft: 'int',

		// objects defined below
		player: 'player',
		level: 'level',

		// arrays of primitives or objects
		enemy: ['enemy'],

		// dictionaries of primitives or objects
		levelClearTimes: {
			int: 'int'
		},
		levelsById: {
			int: 'level'
		}
	},

	// these are objects defined by the game
	objects: [
		player: {
			position: 'vector2',
			score: 'int',
			jump: 'bool',
			myIntList: ['int'],
		}
		enemy: {
			position: 'vector2',
			health: 'int',
		},
		level: {
			id: 'int',
			tiles: ['tile']
		},
		tile: {
			position: 'vector2',
			type: 'int'
		}
	],
}

The json state will exist in both the logic and the renderer, so object structures are not shared, only the values

data	example	type	index	length (bytes)
pog major version	0	int	0	4
pog minor version	1	int	4	4

* fields are done alphabetically

* vectors and fixed length structs are inline

* arrays, lists and dictionaries are represented as an integer of their total length

* array, list and dictionary reading happens after reading the primitives in the state

* strings are utf32 encoded

tic tac toe example:

{
	// 0 is not taken, 1 is X 2 is O
	board: [
		0, 0, 0,
		0, 2, 0
		1, 0, 0
	]
}

// fields
uint 9  // length of array

// arrays, lists and dictionaries
ubyte 0 // top left
ubyte 0 // top middle
ubyte 0 // top right
ubyte 0 // middle left
ubyte 2 // middle middle
ubyte 1 // bottom left
ubyte 0 // bottom middle
ubyte 0 // bottom right

pong example:

{
	isGameOver: false,
	player1: {
		position: [0, 100],
		score: 1
	}
	player2: {
		position: [100,-100],
		score: 0
	},
	ball: {
		position: [50, 50]
	}
}

Client libraries:

(json schema) => file of native object

(binary data, json schema) => native object

(native object, json schema) => binary data

e.g. csharp

public static string StateFile(string json, string path) {
	// outputs a .cs file to path that has the structure of the json file
}

Button Position Enum

value	name	example (xbox one)
0	null
1	left-face-top	dpad up
2	left-face-right	dpad right
3	left-face-bottom	dpad down
4	left-face-left	dpad left
5	left-shoulder-front	LB
6	left-shoulder-back	LT
7	left-thumbstick	L3
8	right-face-top	Y
9	right-face-right	B
10	right-face-bottom	A
11	right-face-left	X
12	right-shoulder-front	RB
13	right-shoulder-back	RT
14	right-thumbstick	R3
15	middle	Xbox Button
16	middle-left	View Button
17	middle-right	Menu Button

Input Type Enum

value	name
0	null
1	gamepad
2	touch
3	mouse
4	keyboard
5	custom

Hand Enum

value	name
0	null
1	left
2	right

Key Enum

value	name
0	Null
1	ArrowDown
2	ArrowLeft
3	ArrowRight
4	ArrowUp
5	Backspace
6	Tab
7	CapsLock
8	Enter
9	ShiftLeft
10	ShiftRight
11	ControlLeft
12	MetaLeft
13	AltLeft
14	Space
15	AltRight
16	MetaRight
17	ContextMenu
18	ControlRight
19	Backquote
20	Digit1
21	Digit2
22	Digit3
23	Digit4
24	Digit5
25	Digit6
26	Digit7
27	Digit8
28	Digit9
29	Digit0
30	Minus
31	Equal
32	IntlYen
33	KeyQ
34	KeyW
35	KeyE
36	KeyR
37	KeyT
38	KeyY
39	KeyU
40	KeyI
41	KeyO
42	KeyP
43	BracketLeft
44	BracketRight
45	Backslash
46	KeyA
47	KeyS
48	KeyD
49	KeyF
50	KeyG
51	KeyH
52	KeyJ
53	KeyK
54	KeyL
55	Semicolon
56	Quote
57	IntlBackslash
58	KeyZ
59	KeyX
60	KeyC
61	KeyV
62	KeyB
63	KeyN
64	KeyM
65	Comma
66	Period
67	Slash
68	IntlRo