XLANDER(6)

NAME
       xlander - A lunar landing simulation with a twist

SYNOPSIS
       xlander  [  -controls  controls  ] [ -fn font ] [ -gravity
       planet ] [ -lateral value ] [ -repeat ] [ -retro value ]

DESCRIPTION
       XLander is a lunar landing simulation for X.  It  features
       an "out-the-window" scrolling 3-d display.

GAME PLAY
       As  you  play  the game, you will see the landing craft on
       the screen.  The 3-d view follows the craft  around,  lag-
       ging  behind  slightly,  which  gives  a  good illusion of
       motion.

       The lander is equipped with five  thrusters;  four  direc-
       tional  thrusters  which  control  lateral motion, and one
       retroactive thruster  which  fires  downwards  to  produce
       upward  momentum.   Each thruster is activated by pressing
       and holding a particular key.  By default, the  space  bar
       fires the retroactive thruster, and the 8, 2, 4 and 6 key-
       pad keys fire the front, rear, left and right  directional
       thrusters,  respectively.   The  control  keys  can be re-
       mapped using the -control option described below.  You can
       also  use  the  keyboard  arrow  keys  to fire directional
       thrusters if you like.

       Each thruster uses up a particular amount  of  fuel.   The
       retro  thruster  consumes  more  fuel than the directional
       thrusters, since it produces more  thrust  to  combat  the
       force of gravity.  Fuel is indicated on the control panel.
       Once it's gone, you can no longer thrust.

       At the start of the game, your landing craft will be free-
       falling toward the surface.  The goal is to land the craft
       on the landing pad with as  little  vertical  and  lateral
       motion  as  possible.   The  landing  pad  is visible as a
       square on the ground with a flag planted  at  one  corner.
       The shadow of the craft is projected on the ground, allow-
       ing you to see how high it is and where it will land.

       In order to land, you must be going slowly enough in  both
       the  vertical  and  lateral  directions.  Although you can
       land anywhere on the surface, you must land on the landing
       pad  to  get  points.   After each successful landing, the
       program gives you a score based on your vertical and  lat-
       eral speeds, refills your fuel tank, and restarts the sim-
       ulation at a higher difficulty level  (by  increasing  the
       force  of  gravity).  After you crash, the game shows your
       final score and then allows you to either  start  over  or

       quit.

GAUGES AND INDICATORS
       The  lunar  lander is equipped with a number of gauges and
       indicators which tell you its status.  At the left of  the
       gauge  panel  is  a circular heading indicator which tells
       you the lateral direction of the craft.  Next to this is a
       vertical  velocity  gauge,  which  tells  you your rate of
       ascent or descent; after this comes a fuel gauge, followed
       by  a  radar screen which tells you your position relative
       to the landing pad.

OPTIONS
       -controls controls
              Configure the keyboard controls  used  by  xlander.
              You  should  pass  a  string  of 5 characters.  The
              first character is the key used to thrust  forward,
              followed  in order by the keys used to thrust back-
              ward, left, and right.  After this comes the  retro
              thrust key.  The default control string is "8246 ".
              If you are used to the vi editor, you might want to
              try using the control string "kjhl ".

       -fn font
              Select  the  font  used to display the text used by
              the program.

       -gravity planet
              Simulate gravity of a particular  planet  or  other
              heavenly body.  Valid planets are:  moon (default),
              earth,  mercury,  venus,  mars,  jupiter,   saturn,
              uranus, neptune, and pluto.  This option also auto-
              matically adjusts the amount  of  retro  thrust  to
              suit the gravity of the planet (unless you override
              it using the -retro option).

       -lateral value
              Specify the amount of thrust, in ft/sec^2, provided
              by the four lateral thrusters on the craft.

       -repeat
              Do  not turn off key repeat for the duration of the
              game.
              Since thrust is activated  by  holding  down  keys,
              xlander  turns off auto key repeat during the game.
              This prevents keypress events from  getting  backed
              up in the queue.  When the game exits, the original
              key repeat mode is restored.  This option  disables
              this behavior.

       -retro value
              Specify the amount of thrust, in ft/sec^2, provided
              by the retroactive thruster.

BUGS
       Collision detection needs (a lot of)  work.   Suggestions,
       anyone?

       Since  we're  not  physicists  or mathematicians, we don't
       claim that this is a completely accurate simulation.   So,
       have fun with it but don't take it too seriously!

AUTHORS
       Paul Riddle paulr@umbc3.umbc.edu
       Mike Friedman mikef@umbc3.umbc.edu

SEE ALSO
       xwave(1)