pong-box2d

A JavaScript Pong engine for Node.js and Browsers.
This repo has two parts:

• A physics engine, box2dPhysics.js based on box2d engine
• A game engine, pongGame.js which wraps the physics engine and adds game logic such as player and score management

This package is designed to be generic and could be used both for Hot Seat games in a browser or as a logic core for client-server multiplayer application.
This package does not address any network or rendering features and is focused only on the game.

See Pong MMO game documentation for design docs of a real client-server application that utilizes this package.

Contents

• ./index.js - main script and wrapper to everything, methods:
  • create(width, height) - method that creates a PongGame object with default Physics engine
• ./pongGame.js - exposes PongGame, game logic container, properties:
  • constructor(physicsEngine)
  • getBallAndPaddlePositions() - returns current locations of paddles and the ball
  • getParametersAndState() - returns game field size and players who joined the game
  • getEventsEmitter() - returns EventEmitter that emits game events like:
    • PLAYER_SCORE_CHANGED - when score changes
    • PLAYER_JOINED - when a player joins the game
    • PLAYER_QUIT - when a player disconnects
    • PLAYER_READY - when a player sent command READY
    • MATCH_STARTED - when a match has started after all players are READY and ball started moving
    • MATCH_STOPPED - when a match has stopped after a player quites and if match was started before
  • joinPlayer(playerObj) - join game, where playerObj is any object that has unique id property
  • quitPlayer(playerId) - quit game, playerId is the same id property from joinPlayer function
  • handlePlayerCommand(playerId, command, data) - handle command from player where command argument can be:
    • READY - indicates that the player is ready for a match, once all players are ready the ball will start moving
    • MOVE_PADDLE - move paddle in direction PongGame.paddleMoveDirection.UP or PongGame.paddleMoveDirection.DOWN
• ./physics/box2dPhysics.js - physics engine that registers bounces, properties:
  • constructor(width, height, ballRadius)
  • addPaddle(playerType, size) - add paddle to field, playerType is Physics.playerType.LEFT/Physics.playerType.RIGHT, size is Object{width, height}
  • removePaddle(playerType) - remove paddle
  • positionBall(position, speed) - place a ball at position Object{x, y} and give it an impulse speed Object{x, y}
  • tick(period, accuracy) - perform physics simulation, period is amount of seconds to simulate, accuracy is number of iterations for algorithms
  • getBallAndPaddlePositions() - returns current positions {{ball: {x, y}, paddles: Array}}
  • giveImpulseToPaddle(playerType, direction) - move paddle up or down, direction is Object{x, y}
  • onBallScored(callback) - register callback event for situation when a ball touches left or right wall playerType is passed to callback, while score must be kept in game logic
• ./tests/ - Jasmine unit tests
• ./demo/ - html files for integration testing and debuggin in browser
  • physics-engine-standalone-demo.html - a simple HTML page with box2d DebugDraw, very convenient to debug the physics engine in isolation
  • pong-game-integration-demo.html - a demo/integration test of the whole package with all available functions and callbacks
• Makefile - make file with some common tasks

Browser support

The game works in Chrome Version 24 but should work in older browsers as well.
The code uses EcmaScript 5 map/reduce/forEach functions, you may want to shim them if you want to run it in IE8.
EcmaScript 6 shim is used for Map functionality as well.

Compilation for running demos in Browsers

To compile client version run:

• make components to download all dependencies
• make build to build a component

Running tests

Use jasmine-node for unit tests execution.
Run make test to execute tests in console.

License MIT

Copyright 2012 Konstantin Raev ([e-mail])

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.