private void updateNPC(PacketBuilder packet, NPC npc) {
		/*
		 * Calculate the mask.
		 */
		int mask = 0;
		final UpdateFlags flags = npc.getUpdateFlags();

		if(flags.get(UpdateFlag.TRANSFORM)) {
			mask |= 0x1;
		}
		if(flags.get(UpdateFlag.FACE_ENTITY)) {
			mask |= 0x40;
		}
		if(flags.get(UpdateFlag.HIT)) {
			mask |= 0x80;
		}
		if(flags.get(UpdateFlag.GRAPHICS)) {
			mask |= 0x4;
		}
		if(flags.get(UpdateFlag.FORCED_CHAT)) {
			mask |= 0x20;
		}
		if(flags.get(UpdateFlag.FACE_COORDINATE)) {
			mask |= 0x8;
		}
		if(flags.get(UpdateFlag.ANIMATION)) {
			mask |= 0x2;
		}
		if(flags.get(UpdateFlag.HIT_2)) {
			mask |= 0x10;
		}

		/*
		 * And write the mask.
		 */
		packet.put((byte) mask);

		if(flags.get(UpdateFlag.TRANSFORM)) {
		  //putShortA(transformId)
		}
		if(flags.get(UpdateFlag.FACE_ENTITY)) {
			Entity entity = npc.getInteractingEntity();
			packet.putLEShort(entity == null ? -1 : entity.getClientIndex());
		}
		if(flags.get(UpdateFlag.HIT)) {
			//UByteA - hit
			//UByteA - hitType
			//UByte -
			//UByteS -
		}
		if(flags.get(UpdateFlag.GRAPHICS)) {
			packet.putShort(npc.getCurrentGraphic().getId());
			packet.putInt2(npc.getCurrentGraphic().getDelay());
		}
		if(flags.get(UpdateFlag.FORCED_CHAT)) {
			//putString
		}
		if(flags.get(UpdateFlag.FACE_COORDINATE)) {
			Location loc = npc.getFaceLocation();
			if(loc == null) {
				packet.putLEShort(0);
				packet.putLEShort(0);
			} else {
				packet.putLEShortA(loc.getX() * 2 + 1);
				packet.putLEShort(loc.getY() * 2 + 1);
			}
		}
		if(flags.get(UpdateFlag.ANIMATION)) {
			packet.putShort(npc.getCurrentAnimation().getId());
			packet.putByteS((byte) npc.getCurrentAnimation().getDelay());
		}
		if(flags.get(UpdateFlag.HIT_2)) {
			//UByteS - hit
			//UByteS - hitType
			//UByte -
			//UByteC -
		}
	}