// Pre carga botones

function preCarga(){
	preBoton1 = new Image();
	preBoton2 = new Image();
	preBoton3 = new Image();
	preBoton4 = new Image();
	preBoton5 = new Image();
	preBoton6 = new Image();
	
	preBoton1.src = "images/bt1_on.png";
	preBoton2.src = "images/bt2_on.png";
	preBoton3.src = "images/bt3_on.png";
	preBoton4.src = "images/bt4_on.png";
	preBoton5.src = "images/bt5_on.png";
	preBoton6.src = "images/bt6_on.png";
}