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Thread: rotating 2 images in opposite directions

  1. #1
    Join Date
    Jul 2012
    Posts
    14

    rotating 2 images in opposite directions

    I can't seem to have 2 images rotating in opposite directions within the same Script. Im trying to keep my code really clean, and I am a beginner to Javascript. Can anyone help? here is my code...

    Code:
      <script type="text/javascript">
                var cog = new Image();
    			var cog2 = new Image();
                
    			function init() {
                    cog.src = 'images/bigwheel.png';
                    setInterval(draw,10);
                }
    			
    			function init() {
                    cog2.src = 'images/smallwheel.png';
                    setInterval(draw,10);
                }
    			
                var rotation = 0;
                function draw(){
                    var ctx = document.getElementById('bigwheelcanvas').getContext('2d');
                    ctx.globalCompositeOperation = 'destination-over';
                    ctx.save();
                    ctx.clearRect(0,0,173,173);
                    ctx.translate(86.5,86.5); // to get it in the origin
                    rotation +=.1;
                    ctx.rotate(rotation*Math.PI/64); //rotate in origin
                    ctx.translate(-86.5,-86.5); //put it back
                    ctx.drawImage(cog,0,0);
                    ctx.restore();
    			}
    			init();
    			
    			var rotation = 0;
                function draw(){
                    var ctx = document.getElementById('smallwheelcanvas').getContext('2d');
                    ctx.globalCompositeOperation = 'destination-over';
                    ctx.save();
                    ctx.clearRect(0,0,150,150);
                    ctx.translate(75,75); // to get it in the origin
                    rotation -=.1;
                    ctx.rotate(rotation*Math.PI/64); //rotate in origin
                    ctx.translate(-75,-75); //put it back
                    ctx.drawImage(cog2,0,0);
                    ctx.restore();
    			}
    			init();	
    
            </script>
    HTML

    Code:
    <div id="bigwheel">
    	
        <canvas id="bigwheelcanvas" width="173" height="173"></canvas>
    
    </div><!--bigwheel-->
    
    <div id="smallwheel">
    	
      <canvas id="smallwheelcanvas" width="150" height="150"></canvas>
    
    </div><!--smallwheel-->

  2. #2
    Join Date
    Jun 2004
    Location
    Portsmouth UK
    Posts
    2,709
    Code:
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
        "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    
    <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
    
    <head>
      <title></title>
    </head>
    
    <body>
    <div id="bigwheel">
    
        <canvas id="bigwheelcanvas" width="173" height="173"></canvas>
    
    </div><!--bigwheel-->
    
    <div id="smallwheel">
    
      <canvas id="smallwheelcanvas" width="150" height="150"></canvas>
    
    </div><!--smallwheel-->
      <script type="text/javascript">
                var cog = new Image();
    			var cog2 = new Image();
    
    			function init() {
                    cog.src = 'http://www.vicsjavascripts.org.uk/StdImages/Egypt5.jpg';
                    draw('bigwheelcanvas',cog,173,173,0,0.1);
                }
    
    			function init2() {
                    cog2.src = 'http://www.vicsjavascripts.org.uk/StdImages/Egypt5.jpg';
                    draw('smallwheelcanvas',cog2,150,150,0,-0.1);
                }
    
                function draw(id,img,w,h,cnt,i){
                    var ctx = document.getElementById(id).getContext('2d');
                    ctx.globalCompositeOperation = 'destination-over';
                    ctx.save();
                    ctx.clearRect(0,0,w,h);
                    ctx.translate(w/2,h/2); // to get it in the origin
                    cnt +=i;
                    ctx.rotate(cnt*Math.PI/64); //rotate in origin
                    ctx.translate(-w/2,-h/2); //put it back
                    ctx.drawImage(img,0,0);
                    ctx.restore();
                    setTimeout(function(){ draw(id,img,w,h,cnt,i); },10);
    	     	}
    
    			init();
    			init2();
    
            </script></body>
    
    </html>
    Vic

    God loves you and will never love you less.

    http://www.vicsjavascripts.org/Home.htm
    If my post has been useful please donate to http://www.operationsmile.org.uk/

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