//Setting Offset of Draggable DIV
offset.left = Math.round((my.x*tile.width)-(screen.width/2));
            if((my.y % 2) == 0){
                offset.left = Math.round((my.x*tile.width)-(screen.width/2)+(tile.width/2));
            }
offset.top  = Math.round((my.y*(tile.height/2))-(screen.height/2)+(tile.height/2));

     $('screen').append('<div class="map" style="left:'+(offset.left*-1)+'px;top:'+(offset.top*-1)+'px"></div>');

//Calculate Start X/Y End X/Y to draw tiles
 var startX = Math.floor(offset.left/tile.width)-1; //+1 and -1 makes one line more than needed to display
            var endX = Math.round((offset.left+screen.width)/tile.width)+1;
            var startY =Math.floor(offset.top/tile.height)*2-1;
            var endY =Math.round((offset.top+screen.height)/tile.height)*2+1;

 for(var y = startY;y<=endY;y++){
                for(var x= startX;x<=endX;x++){
//draw tile
}
}