Go over WebSocket

Go is an ancient game that involves two players competing on a grid for space. The goal is to surround the largest amount of area. See the above Wikipedia article for more information.

I started this project for three reasons:

1. I like the game of Go
2. Playing it requires a board and a bunch of stones (web is better than real life)
3. I wanted to learn the HTML5 Canvas and WebSocket APIs

I started thinking about reason 3 during a talk at Cascadia Ruby conference in Portland, the speakers were showing off a WebSocket-based chat app that the audience was participating in.

TODO:

• Implement Pair, Set, Graph
• hook up graph North,South,East,West edges on Board.putPiece
• Switch the order of the board coordinates so x is first, y is second
• Add Queue#contains
• Vertex holds a Pair of coordinates
• Adding makes an edge from the pairs of the adjacent vertices
• Use new Pair, Set and Graph types
• Add Set#remove
• Find neighborhood of vertex
• Implement BFS to find connected components
• Define libertiesCount() function to count the liberties of a component
• Handle components of size 1
• Add scoring rules to program
• Make grid size variable
• Save state in localStorage
• Add clear board button
• Hook up a WebSocket
• set up backend

Data Structures

The board is represented using a 2D array of Vertex objects, each of which has a color property.

The color defaults to null, but can be switched to black or white.

Each vertex is represented as a Pair of coordinates, and has up to four neighbors, for each pair of adjacent vertices, we use a Set to represent an undirected edge in a Graph.

Using the graph, a ComponentMap object is used to find the connected components, then expose an iterator that visits each component once.

Algorithms

• BFS (Breadth-First Search) to find connected components of pieces.