Killer Game Programming in Java

Watching the Server

A TourWatcher thread monitors the server's output, waiting for messages. The message types are listed below with a brief description of what the TourWatcher does in response:

create n x z

Create a distributed sprite in the local world with name n at position (x, 0, z). By default, the sprite will face forward along the positive z-axis.

wantDetails A P

The client at IP address A and port P is requesting information about the local sprite on this machine. Gather the data and send the data back in a "detailsFor" message.

detailsFor n1 x1 z1 r

Create a distributed sprite with the name n1 at location (x1,0,z1), rotated r radians away from the positive z-axis.

n < move or rotation command >

< command > can be one of forward, back, left, right, rotCClock, or rotClock. The distributed sprite with name n is moved or rotated. rotCClock is a counter-clockwise rotation, and rotClock is clockwise.

n bye

A client has left the world, so the distributed sprite with name n is detached (deleted).

The activities using these messages are shown in Figures Figure 32-6, 32-7, and 32-8.

Almost all the messages are related to distributed sprites in the local world: creation, movement, rotation, and deletion. Therefore, these tasks are handled by TourWatcher, which maintains its sprites in a HashMap, mapping sprite names to DistTourSprite objects:

    private HashMap visitors;   // stores (name, sprite object) pairs

The run() method in TourWatcher accepts a message from the server and tests the ...