pkg://tclrobots-1.0.tar.gz:53994/tclrobots.txt
downloads
TclRobots(6) Tcl/Tk TclRobots(6)
TclRobots
Copyright 1994 Tom Poindexter
tpoind@advtech.uswest.com
tpoindex@nyx.cs.du.edu
WHAT IS TCLROBOTS?
TclRobots is a programming game, not unlike 'Core War'.
To play TclRobots, you must write a Tcl program that con-
trols a robot. The robot's mission is to survive a battle
with other robots. Two, three, or four robots compete
during a battle, each running different programs (or pos-
sibly the same program in different robots.) Each robot
is equipped with a scanner, cannon, drive mechanism. A
single match continues until one robot is left running. A
tournament can be run with any number of robot programs,
each robot playing every other in a round-robin fashion,
one-on-one. A battle simulator is available to help debug
robot programs.
The TclRobots program provides a physical environment,
imposing certain game parameters to which all robots must
adhere. TclRobots also provides a view on a battle, and a
controlling user interface.
TclRobots is strongly influenced by my 1985 game, CROBOTS.
CROBOTS is based on writing robot control programs in C,
and the entire environment is tightly coupled into a sin-
gle program that contains a small C compiler, virtual
stack-based CPU, multi-tasking scheduler, and execution
environment. TclRobots instead is loosely coupled, uti-
lizing separate Tcl wish interpreters for each robot.
Communication between a robot and the TclRobots program is
accomplished with Tk's send command.
TclRobots requirements: a wish interpreter built from Tcl
7.3 and Tk 3.6.
TclRobots uses the Tk "send" command - if your X server is
insecure (xhost access list not empty), you will need a
wish compiled with the "-DNO_TK_SECURITY" flag. Better
yet, use "xauth" instead of "xhost."
Availability:
TclRobots (and Tcl/Tk, if you don't already have it) are
available at the following locations:
ftp://harbor.ecn.purdue.edu/pub/tcl/code/tclrobots-1.0.tar.gz
ftp://ftp.cs.berkeley.edu/ucb/tcl/tcl7.3.tar.Z
ftp://ftp.cs.berkeley.edu/ucb/tcl/tk3.6.tar.Z
8/11/94 1
TclRobots(6) Tcl/Tk TclRobots(6)
INSTALLATION AND DEMO
- Edit the Makefile. All that is needed it the path
of your wish executable, and the directory where
you would like TclRobots installed. See the com-
ments at the top of the Makefile. `make' to
install.
- run `tclrobots' from the directory where you
unpacked the distribution.
- Double-Click on the `samples' directory in the
Files listbox.
- Click on `Select All'
- Click on `Run Battle'
SYNOPSIS
tclrobots [ [ -t timelimit ] [ -o results-file ]
files... ]
Tclrobots without any command line arguments starts
TclRobots in interactive mode. The user interface
(described below) is used to select files, start battles,
tournaments, or the simulator.
If command line arguments are specified, tclrobots starts
in tournament mode using the specified files. Options:
-t timelimit sets the number of minutes to run each match
in a tournament. Timelimit should be specified as
an integer number of minutes. If -t is omitted,
matches run a maximum of 10 minutes each.
-o results-file specifies the file name in which to
record tournament results. If -o is omitted, the
file name "results.out" is used.
THE ROBOT
All robots in TclRobots are constructed equally. What
differentiates the robots' behavior is the control program
that you write. The robot has the ability to move, look
for, and shoot at, other robots.
Robots use a compass system based on 0 to 359 degrees,
with 0 pointing due east, 90 due north, 180 due west, and
270 due south.
The robot's drive mechanism can be controlled to move the
robot in a particular direction, at some speed. Direction
is expressed as an integer degree heading 0 - 359, and
8/11/94 2
TclRobots(6) Tcl/Tk TclRobots(6)
speed is 0 to 100 percent. The motor is inefficient above
35% speed, and begins to overheat. When a heat index of
200 is reached, the motor cannot be operated over 35%
until cooling allows the heat index to drop back to 0.
While the robot is very agile and stable, safeguards are
built into the interface to prevent the robot from tipping
over while trying to turn at too fast a rate for any given
speed.
The following table represents maximum speeds at which a
delta course change can be made:
Degrees of Maximum
course change Speed
------------------------
25 or less 100%
25 - 50 50%
50 - 75 30%
75 or greater 20%
If a course change is attempted at a speed above the maxi-
mum for the change, the drive is disengaged (speed set to
0) on the present course. The drive mechanism also allows
the robot to turn faster at slower speeds.
Speed Rate of turn
per second
---------------------------
25% or less 90
25 - 50% 60
50 - 75% 40
75% or more 30
At 100% speed, the robot travels at 20 meters per second.
Robots are also subject to acceleration and deacceleara-
tion, a linear constant of 20% speed per second.
Each robot is equipped with a scanning device, which can
be pointed independently of the current drive heading of
the robot. A scan can be initiated in any direction,
0-359 degrees. The scanner has a variable resolution
capability, detecting other robots within a maximum of +/-
10 degrees from the scan direction. If a scan finds a
robot, the distance to the opposing robot is reported.
However, if a resolution greater than 0 is used, the scan-
ner's result may be reported inaccurately. In this case,
the distance reported may be off by as much as 10 meters
for each degree of resolution (up to 100 meters in error
for a +/- 10 degree resolution scan.) A high resolution
scan (0 specified for resolution) will always return accu-
rate results.
If two or more robots are in the scan's resolution, the
closest opponent is reported. It's also possible to
8/11/94 3
TclRobots(6) Tcl/Tk TclRobots(6)
distinguish various opposing robots, as the scanner has a
rudimentary digital signal processor, and each robot has a
arbitrary signature. A robot program can also be alerted
when it is the subject of a scan by another robot. The
signature of the scanning robot can be determined, but not
it's heading or distance.
A cannon is the robot's offensive weapon, firing a shell
at opposing robots. The cannon has a maximum range of 700
meters, and can be aimed independently of robot heading.
Damage to all surrounding robots is assessed as follows:
Meters from % Damage
explosion incurred
-----------------------
10 10%
20 5%
40 2%
While the robot has an large (unlimited) cache of shells
available, it can only reload fast enough to have one
shell in the air at maximum range at any one time (approx-
imately 4 seconds). Cannon shells are grouped four to a
clip; after a clip is exhausted, it is ejected and a new
clip loaded in place. The effect is that on every fourth
shell, the reload time is tripled (12 seconds.) The can-
non fires its shells in a high arc; a shell will not
impact into another robot that might be in the line of
flight. Shells travel at 200 meters per second toward the
target.
Various feedback registers in the robot can be accessed by
the control program, reporting the current amount of dam-
age, x and y battlefield location, current speed, and an
internal clock tick.
Robots incur damage expressed as a percent value. When
100% damage is reached, the robot is "dead", and ceases to
function. However, damage has no effect on operational
ability. A robot with 99% damage operates as well as one
with no damage.
THE BATTLEFIELD
The battlefield in TclRobots is a 1,000 by 1,000 meter
square area. Walls surround the battlefield, and robots
running into a wall will suffer 5% damage. The coordinate
system is based on increasing x and y axis values from the
southwest corner (bottom left is 0,0). 999,999 is the
extreme northeast (upper right).
Upon start up, robots are placed in random quadrants.
8/11/94 4
TclRobots(6) Tcl/Tk TclRobots(6)
THE ROBOT TCL LANGUAGE
Robot control programs are written in the Tcl language.
The following Tcl commands are available:
after if rename
append incr return
array join scan
break lappend set
case lindex source
catch linsert split
concat list string
continue llength switch
error lrange time
eval lreplace trace
exit lsearch unset
expr lsort update
file pid uplevel
for proc upvar
foreach rand while
format regexp
global regsub
Note that the after and update commands from Tk are avail-
able. See the Tcl and Tk man pages for information on
these commands.
THE ROBOT HARDWARE INTERFACES
The following Tcl commands are the interface to the
robot's hardware (syscalls.) Each interface command takes
a minimum of 100 milliseconds to complete (except the
scanner command, which requires 200 milliseconds.) Com-
mands that take arguments will return -1 if any argument
is out of valid ranges. For degrees, valid values are
0-359; for speed, 0-100, for resolution, 0-10, for cannon
range, 0-700.
scanner degree resolution
The scanner command invokes the robot's scanner.
Degree must be in the range 0-359. Scanner returns
0 if nothing found, or an integer greater than zero
indicating the distance to an opponent. Resolution
controls how wide in degrees the scan can detect
opponents from the absolute scanning direction, and
must be in the range 0-10. A robot that has been
destroyed is not reported by the scanner.
dsp
The dsp command returns a list of two integers, the
first element is the digital signature of the last
robot found using the scanner. The second element
is the percent of damage the scanned robot has
accumulated, 0-99 percent. Each robot in a battle
8/11/94 5
TclRobots(6) Tcl/Tk TclRobots(6)
has a distinct signature. If nothing was found
during the last scan (scanner command returned 0),
then the dsp command will return "0 0".
alert proc-name
The alert command names a procedure to be called
when the robot is being scanned by another robot.
When the robot detects it has been scanned, the
proc-name procedure is called with one argument,
the dsp signature of the robot that performed the
scan. If proc-name is null (""), then the alert
feature is disabled.
cannon degree range
The cannon commands fires a shell in the direction
specified by degree, for the distance range. Can-
non returns 1 if a shell was fired; if the cannon
is reloading, 0 is returned.
damage
The damage command reports the current percent of
damage suffered by the robot, 0-99. At 100% dam-
age, the robot is "dead", and as such, the control
program is no longer running.
drive degree speed
The drive command starts the robot's drive mecha-
nism. Degree must be in the range 0-359. Speed
must be in the range 0-100. Any change in course
that falls outside the "Degrees of course change"
table (see "The Robot", above) will cause the
robot's speed to be set to 0 along the current
course. A speed of 0 causes the robot to coast to
a stop. The drive command returns the speed set.
If the drive is currently overheated, the maximum
speed during overheating (35%) will be set.
speed
The speed command reports the current speed of the
robot, 0-100. Speed may return more or less than
what was last set with the drive command because of
acceleration/deaccelearation, drive overheating, or
collision into a wall.
heat
The heat command returns a list of two integers,
the first element is the overheating flag, 1 if the
maximum heat value was attained, otherwise 0. The
second element is the current heat index, 0-200.
loc_x
The loc_x command returns the current x axis loca-
tion of the robot, 0-999 meters.
8/11/94 6
TclRobots(6) Tcl/Tk TclRobots(6)
loc_y
The loc_y command returns the current y axis loca-
tion of the robot, 0-999 meters.
tick
The tick command returns the current robot clock
tick, which has a 500 millisecond resolution. The
clock is set to 0 upon robot startup.
Convenience commands
The following Tcl commands are available to the robot con-
trol program. As such, they execute immediately without
the 100 millisecond interface time.
dputs args
The dputs command prints a message on the robot's
status window. Dputs accepts any number of argu-
ments.
rand max
The rand command is a simple random number genera-
tor, based on Knuth's algorithm. The rand command
returns an integer between 0 and ( max - 1), where
max is in the range 1 to 65535. The seed value is
randomly set; if a particular seed value is
desired, the global variable _lastvalue may be set
to a value between 0-65535.
WRITING ROBOT CONTROL PROGRAMS
Several internal variables and procedures are loaded into
a robot before loading the robot control program.
Reserved variables and commands begin with and underscore
"_" or dot ".". Do not use variables or procedures in
robot control program that begin with either symbol.
Robot control programs may set variables or define proce-
dures as required. Robot control programs should never
exit, as they will not be restarted by TclRobots. Thus,
the main processing should be enclosed in an endless loop,
e.g. "while 1 { ... }"
Most standard Tcl commands are available to robot control
programs. Notable Tcl commands that are missing: all file
I/O ( gets, puts, open, close, etc.), exec, info, standard
Tcl library procs ( auto_load, unknown, tkerror etc.)
In addition, most standard Tk commands are also missing.
Tk commands that are available are after and update. Each
syscall implicitly performs the update command, or the
programmer can execute it any time to ensure that commands
8/11/94 7
TclRobots(6) Tcl/Tk TclRobots(6)
scheduled with after are run.
Any "unknown" procedure, or "tkerror" situation is
reported in the robot's status window, and the robot pro-
gram will terminate.
Robot control programs may also examine (but not set) the
global variable _debug to cause debugging code to be exe-
cuted during battle simulation. _debug is set to 1 if
running in the simulator, 0 otherwise. (see "The Simula-
tor" below.)
If the alert command is used, the procedure it specifies
should exist, and take one argument, e.g.
proc I_Was_Scanned {who} {
dputs $who scanned me!
}
alert I_Was_Scanned
Any valid filename can be used for a robot control pro-
gram; a suffix of .tr is recommended to indicate a
TclRobots file.
THE TCLROBOTS USER INTERFACE
TclRobots has a user interface to start battles, run the
simulator, commence a tournament, and view battles in
progress. Upon startup, TclRobots displays a bar of five
buttons, and two listboxes. The buttons are:
- Run Battle - runs a battle with selected robots
- Simulator.. - starts the simulator dialog
- Tournament.. - starts the tournament controller
- About.. - a small about box with TclRobots version
number
- Quit - immediately exits TclRobots
The two listboxes are a file section box (left side), and
a list of selected robot files (right side).
The file section box presents a list of directories and
files in the current directory. Double-clicking on a
directory changes to that directory. Double-clicking on a
file chooses that file to be run in a battle, simulator,
or tournament. A file filter entry is presented at the
top of the file selection box and may be used to filter
the selection by entering a pattern and pressing "Filter".
At the bottom of the file selection list is a file selec-
tion. Entering a file and pressing "Select" will enter
8/11/94 8
TclRobots(6) Tcl/Tk TclRobots(6)
that file in the "Robot Files Selected" list. The button
labeled "Select All" will select all files in the file
selection box to the Robot Files Selected list.
Robot files should be selected before pressing "Run Bat-
tle", "Simulator..", or "Tournament..". To run a single
battle, select two to four robot files from the file
selection list. A single file may be selected more than
once; separate robots will be loaded with the same file.
If the "Simulator.." button is pressed, the first file in
the Robot Files Selected list will be used for the Simula-
tor. If the "Tournament.." button is pressed, all files
in the Robot Files Selected list will be run in a tourna-
ment fashion. In a tournament, duplicate files will be
removed from the list.
The Robot Files Selected listbox has two buttons,
"Remove", and "Remove All". Selecting a file by single
clicking and pressing the Remove button will remove that
file from the list. The Remove All button will remove all
files from the Robot Files Selected list.
Robot files selected are not verified; if a file other
than a TclRobots robot control program is selected,
results are unpredictable.
When "Run Battle" is pressed, TclRobots will spawn a new
wish interpreter, position it to the right of the main
window, and load it with a selected robot control program.
After all robot wish interpreters are spawned, the file
selection frame is replaced with a view on the battlefield
and the battle will commence. Each robot is assigned a
specific color, and is represented on the battlefield by a
unique arrow shape of that color. When a robot issues the
scanner command, the scan is represented by a dotted line
emanating from the robot. Shells fired by a robot are
represented by a small black dot. The robot's current
damage status is shown below the robot's file name, just
above the battlefield.
During a battle, the "Run Battle" button is replaced, by
"Halt". If pressed, the current battle is halted, and the
spawned robot interpreters exit. The "Halt" button is
then replaced with "Reset", which removes the battlefield,
and presents the file selection frame.
Individual wish interpreters for the robots contain a
listbox and scrollbar, which hold output from the "dputs"
command.
8/11/94 9
TclRobots(6) Tcl/Tk TclRobots(6)
THE SIMULATOR
The "Simulator.." button starts the simulator, using the
first entry in the Robot Files Selected list. A simulator
control window appears, and a target robot is placed in
the middle of the battlefield (500,500).
The Simulator allows a robot program to be examined during
robot execution, revealing important information about the
robot. A robot control program can be set to stop on each
"syscall" (any of the robot hardware interface commands.)
While the robot program is paused, the simulator can query
or set global variables in the robot control program.
The Simulator has its control buttons at the top of the
Simulator window. A checkbutton "Step syscalls" toggles
the single step action of the robot control program. The
button "Single Step" will also set the Step Syscalls
checkbutton, or allow the robot control program to run to
the next syscall if already in Step Syscalls. The button
"5% Hit" simulates the robot incurring damage. The button
"Scan" simulates the robot being scanned by the target.
The target's dsp signature is "1". The button "Close"
will remove the simulator and the spawned robot wish
interpreter, and return to the file selection listbox
frame.
When the "Step Syscalls" button is in the "off" state, the
robot executes its code in real time. During "Single
Step", execution is paused at the next syscall and one
motion time cycle is executed. Thus, time is not accu-
rately represented. The behavior of a robot that is sin-
gle stepped may be exaggerated, especially while the robot
is in motion.
As the robot is simulated, the robot's X and Y location,
current heat index, speed, heading, and damage are
updated. If the simulator is in the Step Syscalls state,
these attributes may also be set by entering a new value.
Parameter fields only accept numeric entries in the range
that is acceptable for any particular parameter. The
"Heat" entry turns red (inverse on monochrome displays)
when the robot's motor is the in overheated state.
The last syscall executed by the robot is shown, along
with the arguments to the call (if any). The return value
from the syscall is shown in parentheses. The current
clock tick is also displayed, but cannot be altered.
At the bottom of the simulator, global variables in the
robot may be examined or set. Entering a variable name in
the "Variable" entry and pressing enter or the "Examine"
button will display the variable's value. Entering a new
value in the "Value" entry and pressing enter or the "Set"
button will set the variable.
8/11/94 10
TclRobots(6) Tcl/Tk TclRobots(6)
TOURNAMENT CONTROLLER
The "Tournament.." button starts the Tournament Controller
window. When the "Start Tournament" button is pressed,
files in the Robot Files Selected window are first scanned
for uniqueness, ignoring any duplicate filenames. A tour-
nament is run on the remaining files in a round-robin
fashion, each robot battling every other, one-on-one.
A time limit is imposed on each battle. The default is 10
minutes per battle, and may be set in the "Maximum minutes
per match" entry. Optionally, tournament results may be
saved into a file by specifying a valid file name in the
"Optional results file" entry.
Results of each individual match are displayed in the
"Results" listbox.
Each battle is scored. A robot winning a match receives
three points. A tie match (both robots still running
after the time limit expires) results in one point each.
At the end of the tournament, robots are ranked according
to total points.
During each match, the main window operates as in "Run
Battle" mode; "Halt may be used to stop a tournament in
progress. The Tournament Controller's window will display
the time remaining in the current match.
INTERNALS
TclRobots implements a small "physics" package (proc
update_robots) to control robot and missile (cannon
shells) movement. The proc is scheduled to run every 500
milliseconds during a battle.
Each robot in a battle executes in a separate wish inter-
preter. When a new robot is started, a series of setup
and interface code is first sent (using "send") to the new
intepreter. A "source" command is also sent to load an
individual robot control program. The interface code that
is sent causes each robot to relay its interface calls
back to TclRobots using the "send" command.
Most commands set parameters in an array that TclRobots
maintains. The "update_robots" proc carries out the
requests. "Scanner" is an exception, in that the scan is
computed and values returned. Commands that return status
information merely return relevant portions of the robot
array.
Cheating?
Since each robot communicates to TclRobots via the send
command, it exposes TclRobots to unauthorized access to
8/11/94 11
TclRobots(6) Tcl/Tk TclRobots(6)
its internals. Thus, a crafty robot programmer may be
tempted to use send to look at or set the state of other
robots. The setup code is modified for each robot, renam-
ing the send command to a randomly generated name. The
Tcl info command is deleted, so that the new send command
name is not readily apparent. However, this method is not
totally foolproof.
Just consider it to be "unsportsman-like" to attempt such
usage of send.
ACKNOWLEDGMENTS
I've used a few pieces of code in TclRobots that I didn't
write, and acknowledge those people:
John Ousterhout - mkDialog, from the "widget"
demo included with Tk
Mark Eichin - rand, from a comp.lang.tcl posting
Bill Burdick - every, from a comp.lang.tcl post-
ing
I also used the file selection box procs from my
"wisql" and "wosql"
programs distributed with Sybtcl and Oratcl.
I'd also like to recognize John Ousterhout again, for cre-
ating Tcl/Tk and making it available to the world. Tcl/Tk
is such a flexible language - I was able to graft in the
simulator and tournament controller as after thoughts,
without changing much existing code.
NOTES
If you are unfamiliar with 'Core war', it is a programming
game based on two assembly language programs running in
one address space of a virtual computer. Programs try to
cause the other to terminate, leaving the winning program
as the only one left running.
From the rec.games.corewar Frequently Asked Questions
(Stefan Strack):
Core War was first described in the "Core War
Guidelines" of March, 1984 by D. G. Jones and A. K.
Dewdney of the Department of Computer Science at
The University of Western Ontario (Canada). Dewd-
ney wrote several "Computer Recreations" articles
in "Scientific American" which discussed Core War,
starting with the May 1984 article.
8/11/94 12
TclRobots(6) Tcl/Tk TclRobots(6)
My CROBOTS game was released in 1985 as PC MSDOS "Share-
ware". It is still available from various FTP archives,
including:
ftp://oak.oakland.edu/pub/msdos/c/crobots.zip
CROBOTS was released in binary form only, and a source
license was available for payment of the shareware fee.
Working on TclRobots has again sparked my interest in such
games, and I'm tempted to update CROBOTS. Any such
release (no promises when that might be) will include
source.
If TclRobots complains that you are using "xhost" style
security, you should either use "xauth" style security, or
recompile your wish interpreter, uncommenting the Tk Make-
file line:
#SECURITY_FLAGS = -DTK_NO_SECURITY
Information on setting up "xauth" is available at:
ftp://harbor.ecn.purdue.edu/pub/tcl/docs/Xauthority.gz
BUGS
TclRobots is inherently simplistic in its treatment of
physics. Part of the goal is to run a challenging game
while still executing and updating the battlefield in a
reasonable time period. I developed TclRobots on a
486-50mhz pc running Linux, and can easily run a four
robot battle (five wish interpreters running.)
I've fixed the size of the main window, largely for ease
of plotting the robots and missiles in the canvas. Cur-
rently the canvas is 500x500 pixels, so reducing the bat-
tlefield arena to canvas locations is a simple divide by
two. My intent was to save as much processing during the
update cycle.
The time limit in Tournament mode is not actual wall clock
time, but rather a calculation that assumes the 500 mil-
lisecond tick rate of the physics package is accurate.
The time that "update_robots" takes to run on each tick is
cumulative in distorting tournament time.
The user interface was not designed. Instead, it evolved
from functionality. It could probably stand improvement.
No doubt that some programmers will carefully examine the
"physics" package and exploit its weaknesses. At least it
available for all to see. Some of the ideas I put in
TclRobots that was missing from CROBOTS is the "motor
heating", which should eliminate robots running a full
8/11/94 13
TclRobots(6) Tcl/Tk TclRobots(6)
speed for an extended period of time. Also, the cannon is
limited on its ability for rapid fire by introducing the
notion of a "clip", with longer reloading times.
AUTHOR
Tom Poindexter, Denver, Colorado. Version 1.0 released
August, 1994.
Any suggestions for improvement can be sent to me at
either address listed at the top of this document.
8/11/94 14
