Difference between revisions of "Snake - the game"

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Line 21: Line 21:
 
         }
 
         }
 
     }
 
     }
     var curve = board.createElement('curve', snake.points , {strokeColor:'#B71313',strokeWidth:20,strokeOpacity:0.7});
+
     var curve = board.create('curve', snake.points , {strokeColor:'#B71313',strokeWidth:20,strokeOpacity:0.7});
     var point = board.createElement('point', [
+
     var point = board.create('point', [
 
         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.createElement('text', [2,1,function() { return snake.size; }], {fontSize:'28px'});
+
     var t = board.create('text', [2,1,function() { return snake.size; }], {fontSize:'28px'});
  
 
     var setRandomPosition = function()  {
 
     var setRandomPosition = function()  {
Line 108: Line 108:
 
         }
 
         }
 
     }
 
     }
     var curve = board.createElement('curve', snake.points , {strokeWidth:20,strokeOpacity:0.5});
+
     var curve = board.create('curve', snake.points , {strokeWidth:20,strokeOpacity:0.5});
     var point = board.createElement('point', [
+
     var point = board.create('point', [
 
         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.createElement('text', [2,1,function() { return snake.size; }], {fontSize:'28px'});
+
     var t = board.create('text', [2,1,function() { return snake.size; }], {fontSize:'28px'});
  
 
     var setRandomPosition = function()  {
 
     var setRandomPosition = function()  {

Revision as of 11:02, 5 June 2010

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>
<script type="text/javascript">
    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:'28px'});

    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();
    }
</script>