Saturday, November 12, 2011

A Candy Land Simulator: The Game Engine

Note: this post is from a series on Candy Land.

Last time we captured the board and the card deck into Javascript objects that look like this:

var board = [
    { color: 'Red' },
    { color: 'Orange', bridgeTo: 59 }
    // ...

var cards = [
    'Red'   , 'Red'   , 'Red'   , 'Red'   , 'Red'   , 'Red'   , 'Red'   , 'Red'
    // ...


Now we need to simply draw cards and keep track of a player through the game. I guess we should come up with some simple way to track that. Players will have a name and a position on the board. We also need to know if the player is losing a turn because they stepped on a licorice space. This should do it:

var players = [
    { name: 'Michael', isLosingATurn: false, position: -1 },
    { name: 'Thing 1', isLosingATurn: false, position: -1 },

As we design the rest of the engine, we’ll add to that as necessary.

OK, now we need to create a game loop. A game loop basically covers all the actions that happen in one cycle of the game. Since Candy Land players don’t affect each other (except for a shared deck of cards), all the interesting stuff happens in the player loop, with alternating players.

Here’s a first pass of what we need:

var players = [
    { name: 'Michael', isLosingATurn: false, position: -1, isWinner: false, moves: 0 },
    { name: 'Thing 1', isLosingATurn: false, position: -1, isWinner: false, moves: 0 }

// call "DoGame" to play an entire game, passing in the players array
function DoGame(players){
    // initialize the board
    // initialize the deck

    // call "DoGameLoop" (pass in the board and deck) until it returns false, 
// which indicates the game is over
// when the game is over print out summary stats (e.g move counts) and exit } function DoGameLoop(players, board, cards){ // if all players have finished (yes, my kids insist that the game continues // until everyone finishes :/) exit, the game is over (return false) // for each player: DoPlayerLoop // things went as planned, return true } function DoPlayerLoop(player, board, cards){ // if we are lose a turn, turn off the "isLosingATurn" property and we're done (exit now) // draw a card and increment the "moves" counter // find the next space to move to based on the card // if your move takes you to the last square or beyond, you win // set the "isWinner" property to true and exit // if the space we landed on is a bridge, follow the bridge // if we are now on a lose-a-turn space, turn
// on the "isLosingATurn" property so we know
// to skip our turn the next time around } function DrawACard(cards){ // if there are no cards left in the deck they must have all been played so // reshuffle them! Boom, now there are cards in the deck // remove a card and return it } function MakeDeck(){ // return a new, shuffled deck } function MakBoard(){ // return a new board }

That should read pretty easily from top to bottom (you may have to use your imagination a little bit). We’ll implement some of these in the next post.