Difference between revisions of "Snake - the game"

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Line 24: Line 24:
 
         Math.round(Math.random()*18)+1,Math.round(Math.random()*18)+1],  
 
         Math.round(Math.random()*18)+1,Math.round(Math.random()*18)+1],  
 
         {strokeColor:'#4CADD4',fillColor:'#4CADD4',strokeWidth:10,name:' '});
 
         {strokeColor:'#4CADD4',fillColor:'#4CADD4',strokeWidth:10,name:' '});
     var t = board.create('text', [2,1,function() { return snake.size; }], {fontSize:'28px'});
+
     var t = board.create('text', [2,1,function() { return snake.size; }], {fontSize:28});
  
 
     var setRandomPosition = function()  {
 
     var setRandomPosition = function()  {
Line 110: Line 110:
 
         Math.round(Math.random()*18)+1,Math.round(Math.random()*18)+1],  
 
         Math.round(Math.random()*18)+1,Math.round(Math.random()*18)+1],  
 
         {strokeColor:'#4CADD4',fillColor:'#4CADD4',strokeWidth:10,name:' '});
 
         {strokeColor:'#4CADD4',fillColor:'#4CADD4',strokeWidth:10,name:' '});
     var t = board.create('text', [2,1,function() { return snake.size; }], {fontSize:'28px'});
+
     var t = board.create('text', [2,1,function() { return snake.size; }], {fontSize:28});
  
 
     var setRandomPosition = function()  {
 
     var setRandomPosition = function()  {

Revision as of 19:26, 14 January 2012

This simple version of the old C64 game "snake" is realized completely in JavaScript with JSXGraph. After starting the game the "snake" can be controlled with the arrow up/down/left/right keys.

<link rel="stylesheet" type="text/css" href="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraph.css" />
<script type="text/javascript" src="http://jsxgraph.uni-bayreuth.de/distrib/jsxgraphcore.js"></script>
<form><input type="button" onClick="startGame()" value="start game"></form>
<div id="box" class="jxgbox" style="width:600px; height:600px; overflow:hidden; "></div>
    var board = JXG.JSXGraph.initBoard('box',{originX:0,originY:600,unitX:30,unitY:30,grid:true});
    var snake = {
        points : [[10,11],[10,10]],
        dir : [1,0],
        size: 2,
        newSize: 2,
        speed: 300,
        hitSelf: function(x,y) {
            for (var i=0;i<this.size-1;i++) {
                if (x==this.points[0][i]) if (y==this.points[1][i]) { return true; }
            }
            return false;
        }
    }
    var curve = board.create('curve', snake.points , {strokeWidth:20,strokeOpacity:0.5});
    var point = board.create('point', [
        Math.round(Math.random()*18)+1,Math.round(Math.random()*18)+1], 
        {strokeColor:'#4CADD4',fillColor:'#4CADD4',strokeWidth:10,name:' '});
    var t = board.create('text', [2,1,function() { return snake.size; }], {fontSize:28});

    var setRandomPosition = function()  {
        point.setPositionDirectly(JXG.COORDS_BY_USER,
            Math.round(Math.random()*18)+1,
            Math.round(Math.random()*18)+1);
    }
    var keyDown = function (Evt) {
        var code;
        if (!Evt) Evt = window.event;
        if (Evt.which) {
            code = Evt.which;
        } else if (Evt.keyCode) {
            code = Evt.keyCode;
        }
        // 37: left,  38: up,  39: right,  40: down
        if (code==37) { snake.dir = [-1,0]; return false;}
        else if (code==38) { snake.dir = [0,1]; return false;}
        else if (code==39) { snake.dir = [1,0]; return false;}
        else if (code==40) { snake.dir = [0,-1]; return false;}
        return true;
    }
    document.onkeydown = keyDown;

    var crawl = function() {
        if (snake.size>=snake.newSize) {
            snake.points[0].shift();
            snake.points[1].shift();
        }
        var x = snake.points[0][snake.points[0].length-1]+snake.dir[0];
        snake.points[0].push(x);
        var y = snake.points[1][snake.points[1].length-1]+snake.dir[1];
        snake.points[1].push(y);
        snake.size = snake.points[0].length;
        board.update();
        if (x>=20 || x<=0 || y>=20 || y<=0 || snake.hitSelf(x,y)) {
            alert('Game over');
        } else {
            if (x==point.X()) if (y==point.Y()) {
                snake.newSize += 5;
                snake.speed -= 10;
                setRandomPosition();
                board.update();
            }
            setTimeout(crawl,snake.speed);
        }
    }
    
    var startGame = function () {
        snake.points[0].splice(0,snake.size,10,11);
        snake.points[1].splice(0,snake.size,10,10);
        snake.dir = [1,0];
        snake.size = 2;
        snake.newSize = 2;
        snake.speed = 300;
        setRandomPosition();
        crawl();
    }