public void fire(){
		Bullet bullet = new Bullet(this) ;
		
		if( this.direction == Tank.direction_up){
			bullet.setLocation_x(this.location_x + this.width/2 - bullet.getWidth()/2 - 1);
			bullet.setLocation_y(this.location_y);
		}else if(this.direction == Tank.direction_down){
			bullet.setLocation_x(this.location_x + this.width/2 - bullet.getWidth()/2 - 1);
			bullet.setLocation_y(this.location_y + this.height - 3);
		}else if(this.direction == Tank.direction_left){
			bullet.setLocation_x(this.location_x);
			bullet.setLocation_y(this.location_y + this.width/2 - 1);
		}else if(this.direction == Tank.direction_right){
			bullet.setLocation_x(this.location_x + this.height - 3);
			bullet.setLocation_y(this.location_y + this.width/2 - 1);
		}
		bullet.setDirection(direction);
		//set bullet type
		if( this.tank_type == Tank.HREO){
			bullet.setType(Bullet.BULLET_HERO);
		}else{
			bullet.setType(Bullet.BULLET_ENEMY);
		}
		
		bullet.setMainFrame(this.getMainFrame());
		this.bullts.add(bullet);
		bullet.start();
		
		//sound play
		if( this.tank_type == Tank.HREO){
			SoundPlayFactory.getSoundByName("heroFire");
		}
	}