function animate_up(bg_pos){
	
	var bg = $(".bg[motion]");
	if(bg.attr("motion") != 1) return false;
	
	bg.css("background-position","center -" + bg_pos);
	var bg_height = bg.attr("bg_height"); if(bg_height==0) bg_height = 150;
	
	var limit = bg_height;
	if(bg_pos<=limit){
		bg_pos += 1;
		var t=setTimeout( "animate_up("+bg_pos+");" ,60);
		//alert('oi '+bg_pos);
	} else {
		animate_down(bg_pos);
	}
}
function animate_down(bg_pos){

	var bg = $(".bg[motion]");
	if(bg.attr("motion") != 1) return false;
	bg.css("background-position","center -" + bg_pos);
	
	var limit = 0;
	if(bg_pos>=limit){
		bg_pos -= 1;
		var t=setTimeout( "animate_down("+bg_pos+");" ,60);
		//alert('oi '+bg_pos);
	} else {
		animate_up(0);
	}
}