Index

1. Architecture of Penguin Tower

• penguin tower consists of three main components
  • server, protocol and client
• server is written in Modula-2 and is multi-threaded and uses one thread for each player
  • a thread for each players normal arrow
  • a thread for each players magic arrow
  • a thread for the hand grenade

2. Hand grenade

• a single thread which waits in a loop for the pin to be pulled

• LOOP
     Wait(PinPulled) ;
     Sleep(25) ;
     CalculateDamage
  END

3. Arrow threads

• again LOOP waiting to be released at which time they will be given start coordinates and direction
• they then move the arrow a square at a time (independantly from the rest of the game)
  • apart from areas of mutual exclusion
• when an arrow hits something it determines whether it has hit a person or an object

4. Player threads

• again are continually in a LOOP reading a single character
• depending upon the character the particular operation is performed (see key commands in penguin tower documentation)

5. Multi Threading in the server

• main advantages of threading are:
• conceptually easy to consider each activity in isolation
  • global data structures are protected by mutual exclusive semaphores
• allows independant action of players, arrows and hand grenade
• when a new player joins a new thread is created appropriately
  • likewise when a player leaves or disconnects the thread is disposed

6. Protocol

• the client attempts to connect using a tcp socket on port number 7000 (or higher)
• once connected the client sends single characters to the server
  • except Esc which if pressed terminates the game
• the server sends lines of text to the client
  • each line is terminated by a newline \n character
• the advantages of this approach is
  • simplicity and the ability to test the server and client independantly
  • you can connect to the server using telnet on port 7000
  • likewise you can construct a file containing lines of text which will be read by the client

7. Protocol lines from the server

• each line from the server instructs the client to perform some activity
  • each line received is stored in the history list which could be re-read to give a slow motion (or fast motion) replay
  • see the function processLine in file penguin-tower.py
• sync erases the history list
  • useful so the replay does not become excessively long
• fl flush, forces the client to flip the double buffer
• quit or abort terminates the client
• clear clear the screen
• status draw the status screen with blank entries
• dWriteLn somestring
  • write somestring to the screen and move the cursor to the next line
• dWriteStr somestring
  • write somestring to the screen and leave the cursor at the end of the string
• dC character
  • write the single character to the screen
• eC erase character at the current cursor position
• dN somestring
  • display the name somestring on the status screen
• dMap somestring
  • display the mapname somestring in the status window
• dC1 somestring
  • display somestring in the first line of the comment area
• dC2 somestring
  • display somestring in the second line of the comment area
• dC3 somestring
  • display somestring in the third line of the comment area
• dC4 somestring
  • display somestring in the fourth line of the comment area
• dCMD somestring
  • display the action command in the status window
• eman x y
  • display player facing east at position, x, y
• wman , sman and nman
  • same as eman but facing in respective directions
• Wman , Eman , Sman and Nman
  • display opponent facing the appropriate direction
• hwall x1, y1, x2, y2
  • display a horizontal wall using the coordinates
• vwall x1, y1, x2, y2
  • display a vertical wall using the coordinates
• hhinge x1, y1, x2, y2
  • draw a horizontal hinge using the coordinates
• vhinge x1, y1, x2, y2
  • draw a horizontal hinge using the coordinates
• war , ear , nar , sar x, y
  • draw an arrow facing in a specified direction at position, x, y
• dW somestring
  • draw somestring in the wounds field
• dF , dA , dM dR dT
  • draw fatigue, draw arrow, draw magic arrow, draw room, draw time in the same way as draw wounds
• pS somestring
  • play sound file somestring
• eL x1 y1 x2 y2
  • erase line

Index

This document was produced using groff-1.19.