XLANDER(6)XLANDER(6)NAMExlander - A lunar landing simulation with a twist
SYNOPSISxlander [ -controls controls ] [ -fn font ] [ -gravity planet ] [ -lat‐
eral 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, lagging behind slightly, which
gives a good illusion of motion.
The lander is equipped with five thrusters; four directional 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 keypad 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, allowing
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 simulation 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 circu‐
lar 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 backward, 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
automatically 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 ALSOxwave(1)X Version 11 27 April 1992 XLANDER(6)
