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| window.onload = function() {
var canvasWidth = 900;
var canvasHeight = 600;
var blockSize = 30;
var ctx;
var delay = 100;
var snakee;
var applee;
var widthInBlocks = canvasWidth/blockSize;
var heightInBlocks = canvasHeight/blockSize;
init();
function init() {
var canvas = document.createElement ('canvas');
canvas.width = canvasWidth;
canvas.height = canvasHeight;
canvas.style.border = "1px solid";
document.body.appendChild(canvas);
ctx = canvas.getContext ('2d');
snakee = new Snake([[6,4],[5,4],[4,4],[3,4],[2,4]], "right");
applee = new Apple([10,10]);
refreshCanvas();
}
function refreshCanvas(){
snakee.advance();
if (snakee.checkCollision){
// gameOver();
}
else
{
if (snakee.isEatingApple(applee)){
snakee.ateApple = true;
do{
applee.setNewPosition();
}
while (applee.isOnSnake(snakee))
}
ctx.clearRect(0,0,canvasWidth,canvasHeight);
snakee.draw();
applee.draw();
setTimeout(refreshCanvas,delay);
}
}
function drawBlock(ctx, position) {
var x = position[0] * blockSize;
var y = position[1] * blockSize;
ctx.fillRect(x ,y , blockSize, blockSize);
}
function Snake(body, direction) {
this.body = body;
this.direction = direction;
this.ateApple = false;
this.draw = function()
{
ctx.save();
ctx.fillStyle = "#ff0000";
for(var i = 0; i < this.body.length; i++)
{
drawBlock(ctx, this.body[i]);
}
ctx.restore();
};
this.advance= function() {
var nextPosition = this.body[0].slice();
switch(this.direction)
{
case "left":
nextPosition[0] -= 1;
break;
case "right":
nextPosition[0] += 1;
break;
case "down":
nextPosition[1] += 1;
break;
case "up":
nextPosition[1] -= 1;
break;
default:
throw("Invalid Direction");
}
this.body.unshift(nextPosition);
if(!this.ateApple)
this.body.pop();
else{
this.ateApple = false;
}
};
this.setDirection = function(newDirection) {
var allowedDirections;
switch(this.direction)
{
case "left":
case "right":
allowedDirections = ["up","down"];
break;
case "down":
case "up":
allowedDirections = ["left","right"];
break;
default:
throw("Invalid Direction");
}
if(allowedDirections.indexOf(newDirection) > -1)
{
this.direction = newDirection;
}
};
this.checkCollision = function(){
var wallCollision = false;
var snakeCollision = false;
var head = this.body[0];
var rest = this.body.slice[1];
var snakeX = head[0];
var snakeY = head[1];
var minX = 0;
var minY = 0;
var maxX = widthInBlocks -1;
var maxY = heightInBlocks -1;
var isNotBetweenHorizontalWalls = snakeX < minX || snakeX > maxX;
var isNotBetweenVerticalWalls = snakeY < minY || snakeY > maxY;
if(isNotBetweenHorizontalWalls||isNotBetweenVerticalWalls){
wallCollision = true;
}
for (var i = 0; i < rest.length; i++){
if(snakeX === rest[i][0] && snakeY === rest[i][1]){
snakeCollision = true;
}
}
return wallCollision || snakeCollision;
};
this.isEatingApple = function(appleToEat){
var head = this.body[0];
if(head[0] === appleToEat.position[0] && head[1] === appleToEat.position[1]){
return true
}
else {
return false
}
}
}
function Apple(position){
this.position = position;
this.draw = function(){
ctx.save();
ctx.fillStyle = "#33cc33";
ctx.beginPath();
var radius = blockSize/2;
var x = this.position [0]*blockSize + radius;
var y = this.position [0]*blockSize + radius;
ctx.arc(x,y,radius,0, Math.PI*2, true);
ctx.fill();
ctx.restore();
};
this.setNewPosition = function(){
var newX = Math.round(Math.random() * (widthInBlocks -1));
var newY = Math.round(Math.random() * (heightInBlocks -1));
this.position = [newX, newY];
};
this.isOnSnake = function(snakeToCheck)
{
var isOnSnake = false;
for(var i = 0; i < snakeToCheck.body.length; i++){
if(this.position[0]=== snakeToCheck.body[i][0] && this.position[1]=== snakeToCheck.body[i][1]){
isOnSnake = true;
}
}
return isOnSnake;
}
}
document.onkeydown = function handleKeyDown(e) {
var key = e.keyCode;
var newDirection;
switch (key)
{
case 37:
newDirection = "left";
break;
case 38:
newDirection = "up";
break;
case 39:
newDirection = "right";
break;
case 40:
newDirection = "down";
break;
default:
return;
}
snakee.setDirection(newDirection);
}
}; |
