function preCache(){
	for(var k = 0; k < imgs_data.length; k++){
	  map_imgs[k] = new Object();
	  map_imgs[k]["id"] = imgs_data[k]["id"];
	  map_imgs[k]["i"] = new Image();
	  map_imgs[k]["i"].src = imgs_data[k]["i"];
	}
}

function showMap(_id){
	if(cur_map == _id) return;
	var mbox = document.getElementById('mapbox'+_id);
	if(!mbox) return;
	if(cur_map != false && !isNaN(cur_map)){
		var old_mbox = document.getElementById('mapbox'+cur_map);
		if(old_mbox) old_mbox.className = 'mbox_h';
	}
	clearFilter(_id);
	mbox.className = 'mbox_v';
	startFilter(_id);
	cur_map = _id;	
}

function getMap(_id){
	for(var i = 0; i < map_imgs.length; i++){
		if(map_imgs[i]["id"] == _id) return map_imgs[i];
	}
	return;	
}

function startFilter(_id){
	var mi = document.getElementById('map'+_id);
	if(!mi) return;
	if(mi.filters){
	  mi.filters.item(0).Apply();
	  mi.filters.item(0).Play();
	}
	mi.style.visibility="";
}

function clearFilter(_id){
	var mi = document.getElementById('map'+_id);
	if(!mi) return;
	mi.style.visibility = "hidden";	
}