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script.js
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script.js
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/*jslint browser:true, plusplus:true, vars: true */
"use strict";
// http://stackoverflow.com/questions/13756482/create-copy-of-multi-dimensional-array-not-reference-javascript
//create a clone of current game state board
Array.prototype.clone = function () {
var arr = [], i;
for (i = 0; i < this.length; i++) {
arr[i] = this[i].slice();
}
return arr;
};
function Game() {
var that = this;
this.map = [];
this.paused = false; //flag whether the game is paused or not, this can be true or false
this.won = false; //flag whether the game has been won or not, this can be true or false
this.rejectClick = false; //flag to prevent user from clicking
this.move = 0;
this.aiHistory = [];
this.initOnceDone = false;
/**
* Only initalize once for these functions, can prevent race condition
*/
this.initOnce = function () {
if (this.initOnceDone) {
return false;
}
this.canvas = document.getElementsByTagName("canvas")[0];
//event listener listens for users click and applies their click to the board
this.canvas.addEventListener('click', function (e) {
that.onclick(that.canvas, e);
});
this.context = this.canvas.getContext('2d');
this.initOnceDone = true;
};
this.init = function () {
//initialize variables
this.map = [];
this.paused = false;
this.won = false;
this.rejectClick = false;
this.move = 0;
this.aiHistory = [];
this.initOnce();
var i, j;
//we will create a 2D array representing a blank board in order to initialize the game
for (i = 0; i <= 6; i++) {
this.map[i] = [];
for (j = 0; j <= 7; j++) {
this.map[i][j] = 0;
}
}
//print blank board to screen
this.clear();
this.drawMask();
this.print();
};
this.playerMove = function () {
//determine whether it is a players move. Return 1 if so, else return -1
if (this.move % 2 === 0) {
return 1;
}
return -1;
};
this.print = function () {
var i, j, msg;
msg = "\n";
//display whos move it is: user or AI
msg += "Move: " + this.move;
msg += "\n";
for (i = 0; i < 6; i++) {
for (j = 0; j < 7; j++) {
msg += " " + this.map[i][j];
}
msg += "\n";
}
console.log(msg);
};
this.printState = function (state) {
//display current board state
var i, j, msg = "\n";
for (i = 0; i < 6; i++) {
for (j = 0; j < 7; j++) {
msg += " " + state[i][j];
}
msg += "\n";
}
console.log(msg);
};
this.win = function (player) {
//the following function is used when either player has successfully won
this.paused = true;
this.won = true;
this.rejectClick = false;
var msg = null;
//winning player or draw is displayed
if (player > 0) {
msg = "Player 1 wins";
} else if (player < 0) {
msg = "Player 2 wins";
} else {
msg = "It's a draw";
}
//user has the option to reset the game to play again.
msg += " - Click to reset";
this.context.save();
this.context.font = '14pt sans-serif';
this.context.fillStyle = "#111";
this.context.fillText(msg, 200, 20);
this.context.restore();
console.info(msg);
};
this.fillMap = function (state, column, value) {
//used to update game state. begin by creating a clone of the current board
var tempMap = state.clone();
//if not a valid click, return -1
if (tempMap[0][column] !== 0 || column < 0 || column > 6) {
return -1;
}
//initialize variables
var done = false,
row = 0,
i;
for (i = 0; i < 5; i++) {
if (tempMap[i + 1][column] !== 0) {
done = true;
row = i;
break;
}
}
if (!done) {
row = 5;
}
//set current selected spot to be filled and return the board
tempMap[row][column] = value;
return tempMap;
};
this.action = function (column, callback) {
//if game is paused or won don't complete action
if (this.paused || this.won) {
return 0;
}
//check if it is a valid click
if (this.map[0][column] !== 0 || column < 0 || column > 6) {
return -1;
}
var done = false;
var row = 0, i;
for (i = 0; i < 5; i++) {
if (this.map[i + 1][column] !== 0) {
done = true;
row = i;
break;
}
}
if (!done) {
row = 5;
}
//animate move, show circle falling from top of screen
this.animate(column, this.playerMove(this.move), row, 0, function () {
that.map[row][column] = that.playerMove(that.move);
that.move++;
that.draw();
that.check();
that.print();
callback();
});
this.paused = true;
return 1;
};
this.check = function () {
//check function is used to determine whether there is a current winner
var i, j, k;
var temp_r = 0, temp_b = 0, temp_br = 0, temp_tr = 0;
for (i = 0; i < 6; i++) {
for (j = 0; j < 7; j++) {
temp_r = 0;
temp_b = 0;
temp_br = 0;
temp_tr = 0;
for (k = 0; k <= 3; k++) {
//from (i,j) to right
if (j + k < 7) {
temp_r += this.map[i][j + k];
}
//from (i,j) to bottom
if (i + k < 6) {
temp_b += this.map[i + k][j];
}
//from (i,j) to bottom-right
if (i + k < 6 && j + k < 7) {
temp_br += this.map[i + k][j + k];
}
//from (i,j) to top-right
if (i - k >= 0 && j + k < 7) {
temp_tr += this.map[i - k][j + k];
}
}
//if there is 4 peices in a row, set game to be won
if (Math.abs(temp_r) === 4) {
this.win(temp_r);
} else if (Math.abs(temp_b) === 4) {
this.win(temp_b);
} else if (Math.abs(temp_br) === 4) {
this.win(temp_br);
} else if (Math.abs(temp_tr) === 4) {
this.win(temp_tr);
}
}
}
// check if draw
if ((this.move === 42) && (!this.won)) {
this.win(0);
}
};
this.drawCircle = function (x, y, r, fill, stroke) {
this.context.save();
this.context.fillStyle = fill;
this.context.strokeStyle = stroke;
this.context.beginPath();
this.context.arc(x, y, r, 0, 2 * Math.PI, false);
this.context.fill();
this.context.restore();
};
this.drawMask = function () {
// draw the mask which is the empty game board
// http://stackoverflow.com/questions/6271419/how-to-fill-the-opposite-shape-on-canvas
// --> http://stackoverflow.com/a/11770000/917957
this.context.save();
this.context.fillStyle = "#ddd";
this.context.beginPath();
var x, y;
for (y = 0; y < 6; y++) {
for (x = 0; x < 7; x++) {
this.context.arc(75 * x + 100, 75 * y + 50, 25, 0, 2 * Math.PI);
this.context.rect(75 * x + 150, 75 * y, -100, 100);
}
}
this.context.fill();
this.context.restore();
};
this.draw = function () {
var x, y;
var fg_color;
for (y = 0; y < 6; y++) {
for (x = 0; x < 7; x++) {
fg_color = "transparent";
//if it is player 1s turn, set colour to red and draw a red circle
if (this.map[y][x] >= 1) {
fg_color = "#ff4136";
//else set colour to blue and draw a blue circle for the A1
} else if (this.map[y][x] <= -1) {
fg_color = "#0074d9";
}
this.drawCircle(75 * x + 100, 75 * y + 50, 25, fg_color, "black");
}
}
};
this.clear = function () {
//clear the game board
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
};
this.animate = function (column, move, to_row, cur_pos, callback) {
//function used for animating the tiles dropping down from the top of the screen
var fg_color = "transparent";
//if player 1s move, set colour to red
if (move >= 1) {
fg_color = "#ff4136";
//if player 2s move, set colour to blue
} else if (move <= -1) {
fg_color = "#0074d9";
}
if (to_row * 75 >= cur_pos) {
//animate circle dropping from top of screen
this.clear();
this.draw();
this.drawCircle(75 * column + 100, cur_pos + 50, 25, fg_color, "black");
this.drawMask();
window.requestAnimationFrame(function () {
that.animate(column, move, to_row, cur_pos + 25, callback);
});
} else {
callback();
}
};
this.onregion = function (coord, x, radius) {
//check whether click was in region of the game board
if ((coord[0] - x)*(coord[0] - x) <= radius * radius) {
return true;
}
return false;
};
this.oncircle = function (coord, centerCoord, radius) {
if ((coord[0] - centerCoord[0]) * (coord[0] - centerCoord[0]) <= radius * radius
&& (coord[1] - centerCoord[1]) * (coord[1] - centerCoord[1]) <= radius * radius) {
return true;
}
return false;
};
this.onclick = function (canvas, e) {
//check if game is over or not
if (this.rejectClick) {
return false;
}
//if game has been won start new game
if (this.won) {
this.init();
return false;
}
var rect = canvas.getBoundingClientRect(),
x = e.clientX - rect.left,// - e.target.scrollTop,
y = e.clientY - rect.top;// - e.target.scrollLeft;
var j, valid;
for (j = 0; j < 7; j++) {
if (this.onregion([x, y], 75 * j + 100, 25)) {
// console.log("clicked region " + j);
this.paused = false;
valid = this.action(j, function () {
that.ai(-1);
});
if (valid === 1) { // give user retry if action is invalid
this.rejectClick = true;
}
break; //because there will be no 2 points that are clicked at a time
}
}
};
this.ai = function (aiMoveValue) {
//console.log(this.aiHistory);
var choice = null;
//copy the current state of the board
var state = this.map.clone();
function checkState(state) {
var winVal = 0;
var chainVal = 0;
var i, j, k;
var temp_r = 0, temp_b = 0, temp_br = 0, temp_tr = 0;
//nested for loop used to check the state of the board to determine which is the best move for the AI
for (i = 0; i < 6; i++) {
for (j = 0; j < 7; j++) {
temp_r = 0;
temp_b = 0;
temp_br = 0;
temp_tr = 0;
for (k = 0; k <= 3; k++) {
//from (i,j) to right
if (j + k < 7) {
temp_r += state[i][j + k];
}
//from (i,j) to bottom
if (i + k < 6) {
temp_b += state[i + k][j];
}
//from (i,j) to bottom-right
if (i + k < 6 && j + k < 7) {
temp_br += state[i + k][j + k];
}
//from (i,j) to top-right
if (i - k >= 0 && j + k < 7) {
temp_tr += state[i - k][j + k];
}
}
//compute chain values for heuristic for the AI
chainVal += temp_r * temp_r * temp_r;
chainVal += temp_b * temp_b * temp_b;
chainVal += temp_br * temp_br * temp_br;
chainVal += temp_tr * temp_tr * temp_tr;
//if any value equals 4, meaning there are four in a row, set win value to temp value. meaning we have a winner
if (Math.abs(temp_r) === 4) {
winVal = temp_r;
} else if (Math.abs(temp_b) === 4) {
winVal = temp_b;
} else if (Math.abs(temp_br) === 4) {
winVal = temp_br;
} else if (Math.abs(temp_tr) === 4) {
winVal = temp_tr;
}
}
}
return [winVal, chainVal];
}
function value(state, depth, alpha, beta) {
var val = checkState(state);
if (depth >= 4) { // if slow (or memory consumption is high), lower the value
var retValue = 0;
// if win, value = +inf
var winVal = val[0];
var chainVal = val[1] * aiMoveValue;
retValue = chainVal;
// If a move leads to winning, then execute it
if (winVal === 4 * aiMoveValue) { // return a large value if AI wins because the AI wants to win
retValue = 999999;
} else if (winVal === 4 * aiMoveValue * -1) { // AI loses, AI hates losing, return a low value
retValue = 999999 * -1;
}
retValue -= depth * depth;
return [retValue, -1];
}
var win = val[0];
// if already won, then return the value right away
if (win === 4 * aiMoveValue) { // AI wins, AI wants to win of course
return [999999 - depth * depth, -1];
}
if (win === 4 * aiMoveValue * -1) { // AI loses, AI hates losing, return low value
return [999999 * -1 - depth * depth, -1];
}
if (depth % 2 === 0) {
//compute minmax with alpha beta pruning. min state will return what an optimal users move would be to minimize AIs score
return minState(state, depth + 1, alpha, beta);
}
//if not, then return the move which will maximize the AIs score.
return maxState(state, depth + 1, alpha, beta);
}
function choose(choice) {
return choice[Math.floor(Math.random() * choice.length)];
}
function maxState(state, depth, alpha, beta) {
var v = -100000000007;
var move = -1;
var tempVal = null;
var tempState = null;
var moveQueue = [];
var j;
//compute all possible states of the board at next depth
for (j = 0; j < 7; j++) {
tempState = that.fillMap(state, j, aiMoveValue);
if (tempState !== -1) {
tempVal = value(tempState, depth, alpha, beta);
if (tempVal[0] > v) {
v = tempVal[0];
move = j;
moveQueue = [];
moveQueue.push(j);
} else if (tempVal[0] === v) {
moveQueue.push(j);
}
// alpha-beta pruning
if (v > beta) {
move = choose(moveQueue);
return [v, move];
}
alpha = Math.max(alpha, v);
}
}
move = choose(moveQueue);
return [v, move];
}
function minState(state, depth, alpha, beta) {
var v = 100000000007;
var move = -1;
var tempVal = null;
var tempState = null;
var moveQueue = [];
var j;
for (j = 0; j < 7; j++) {
tempState = that.fillMap(state, j, aiMoveValue * -1);
if (tempState !== -1) {
tempVal = value(tempState, depth, alpha, beta);
if (tempVal[0] < v) {
v = tempVal[0];
move = j;
moveQueue = [];
moveQueue.push(j);
} else if (tempVal[0] === v) {
moveQueue.push(j);
}
// alpha-beta pruning
if (v < alpha) {
move = choose(moveQueue);
return [v, move];
}
beta = Math.min(beta, v);
}
}
move = choose(moveQueue);
return [v, move];
}
var choice_val = maxState(state, 0, -100000000007, 100000000007);
choice = choice_val[1];
var val = choice_val[0];
console.info("AI " + aiMoveValue + " choose column: " + choice + " (value: " + val + ")");
this.paused = false;
var done = this.action(choice, function () {
that.rejectClick = false;
//that.ai(-aiMoveValue);
});
// if fail, then random
while (done < 0) {
console.error("Falling back to random agent");
choice = Math.floor(Math.random() * 7);
done = this.action(choice, function () {
that.rejectClick = false;
});
}
};
this.init();
}
document.addEventListener('DOMContentLoaded', function () {
this.game = new Game();
//this.game.ai(1);
});