dfk@hp-lsd.COS.HP.COM (David F. Kurth) (06/07/91)
This is my first attempt at writing anything substantial for the
HP48 calculator. I wrote this in PASCAL about 10 years ago for
a HP3000 computer, then rewrote it in BASIC for a primative home
computer, and then massaged it into this for a great handheld calculator.
I am not a programmer, but enjoy trying to get something to work
the way I want. This program is by no means perfect, but I enjoy
playing it and wanted to share with everyone else.
Have fun playing.
Dave Kurth
dfk@hp-lsd.cos.hp.com
%%HP: T(3)A(R)F(.);
@ GRAVITY GAME
@
@ Original Concept Stolen From Some Ancient HP Desktop Calculator
@
@ Written for HP48 by Dave Kurth 06Jun91 Ver 1.0
@
@ Object: Launch a missile from your station (a cross or X
@ on the left side of the screen) to hit a target (a bull's-eye
@ on the right side of the screen). Two to five planets affect
@ the missile's path due to their gravitational field. Larger
@ diameter planets have more influence.
@
@ Controls: Your only input is the firing angle of your missile.
@ An angle of 0 degrees shoots horizontal to the right. 90 degrees
@ is straight up. If there is too much planet mass behind your
@ station, you may not be able to reach the target. On the other
@ hand, an indirect missile path may have surprising results.
@ Be careful, or you may hit yourself! Your station and the target
@ have no gravity, so they will not "attract" the missile.
@
@ Caution: This game is realtime. One must realize that when using
@ convention missiles without warp drive travelling way below the
@ speed of light, it takes time to cover such astronomical distances.
@ This game is ideal for long boring meetings where you have time
@ to burn and want everyone to think you're still solving those
@ complicated problems that *required* the purchase of your calculator
@ in the first place.
@
@ Starting: Download the program to the calculator. This is in
@ straight ASCII format, so there is no need to mess with ASC->
@ binary, uuencode, or any other format. Then push the GRAV menu key
@ to start the program.
@
@ For a simple demo, enter "2" for a seed and 10 degrees for the angle.
@ This direct shot takes about 30 seconds.
@ For a crazy demo, enter "2" for a seed and 20 degrees for the angle.
@ Now wait about 7 minutes and see what a different path the missile
@ follows to hit the target. When the missile is travelling, any
@ keystroke (other than ATTN/ON) will abort the current shot. You
@ may abort because you think your shot will miss. If you let the
@ missile continue though, you may find the missile will go around
@ again and eventually hit the target. This is what makes the game
@ fun to watch and predict.
@
@ This is presented with no rights reserved. I take no responsibility
@ for any damage or injury to anyone caused by this program. I
@ believe the physics are correct, but then again all the constants
@ are made up to fit the "universe" on the screen.
@ I'm no expert on the HP48 (I've only had one since Feb). I only
@ wish things would go faster. If you find a way to speed things up,
@ please post the info so I and everyone else may be enlightened.
@ Above all, have fun and maybe you'll learn something new.
@
@ Directory
@ Checksum # CDEEh
@ Bytes 4654
@ Checksum will change after program is run due to creation of variables
@
@
DIR
GRAV
\<< RCLF \-> f @ Save status
\<< 2 CF INIT 2 SF @ Set up variables
WHILE 2 FS? @ Start main loop
REPEAT
SENDMIS
END
f STOF @ Restore status
\>>
{ GRAV } ORDER 2 MENU @ Restore VAR menu with GRAV first
KILL @ Remove HALT annuciator.
\>>
INIT
\<< GETSEED ERASE { #0d #0d} PVIEW
5 'MAX.PL' STO @ Max Number of Planets
4 'T.SIZE' STO @ Target Size radius
3 'S.SIZE' STO @ Station Size radius
10 'MAX.MIS' STO @ Max Number of Missles
10 'MNUM' STO @ Missle Number of Current Shot
5 'TIME.MAG' STO @ Time Magnification when off-screen
1E-3 'MIN.FORC' STO @ Minumum Force to determine Missile lost
12 'VINIT' STO @ Initial Missle Velocity
360 'Gk' STO @ Gravitational Konstant
0 'ANGLE' STO @ Initial Missle Velocity Angle
0.2 'DTIME' STO @ Delta Time
{ } 'POSITION' STO @ Position/Mass Array, Station, Target, + Planets
MAX.PL 1 - RAND * IP 2 + 'NUM.P' STO @ Random number of Planets (2-5)
GENSTAT
GENTARG
GENPLAN
ANGLE SETMIS @ Set missile data in case user doesn't first time
\>>
GETSEED @ Set random number seed
\<<
"Enter random seed or\010"
"Nothing if don't care\010" +
"Push ENTER" +
""
INPUT DUP SIZE
IF 0 \=/
THEN
OBJ\-> RDZ @ If number entered, set seed
ELSE
DROP @ Else clear stack
END
\>>
GENTARG @ Locate and draw target in right half of screen
\<<
POSITION
24 RAND * IP 87 + @ X value
24 RAND * IP 20 + @ Y value
T.SIZE @ Mass (radius) value
3 \->LIST 1 \->LIST + 'POSITION' STO
DTARG
\>>
DTARG @ Draw target
\<<
PICT POSITION 2 GET OBJ\-> DROP2 SWAP 4 - R\->B
SWAP 4 - R\->B 2 \->LIST TARG REPL
\>>
GENSTAT @ Locate and draw station in left half of screen
\<<
POSITION
24 RAND * IP 20 + @ X value
24 RAND * IP 20 + @ Y value
S.SIZE @ Mass (radius) value
3 \->LIST 1 \->LIST + 'POSITION' STO
DSTAT
\>>
DSTAT @ Draw station
\<<
PICT POSITION 1 GET OBJ\-> DROP2 SWAP 3 - R\->B
SWAP 3 - R\->B 2 \->LIST STAT REPL
\>>
GENPLAN @ Locate and draw planets with separation
\<< 3 0 0 \-> i x y
\<<
DO
POSITION
110 RAND * IP 10 + DUP R\->B 'x' STO @ X value
40 RAND * IP 10 + DUP R\->B 'y' STO @ Y value
x y 2 \->LIST DUP 'x' STO PIXON @ Show location temporarily
5 RAND * IP 2 + @ Mass value
3 \->LIST 1 \->LIST + 'POSITION' STO
1 CF
1 i 1 -
FOR j
i j CALDIFF
IF 12 <
THEN 1 SF
END
NEXT
x PIXOFF
IF 1 FC?
THEN @ Location is valid, draw planet
i DPLAN 1 'i' STO+
ELSE @ Invalid location, remove from list
POSITION DUP SIZE 1 - 1 SWAP SUB 'POSITION' STO
END
UNTIL i NUM.P 2 + >
END
\>>
\>>
DPLAN @ Draw one planet
\<<
POSITION SWAP GET OBJ\-> DROP R\->B 3 ROLLD
R\->B SWAP R\->B SWAP 2 \->LIST SWAP
0 6.28 RAD ARC
\>>
CALDIFF @ Calculate distance between surface of planets i & j
\<< \-> i j
\<< @ DIFF = SQRT((Yj-Yi)^2 + (Xj-Xi)^2) - Mj - Mi
POSITION j GET OBJ\-> DROP POSITION i GET OBJ\-> DROP
4 ROLL + 5 ROLLD SWAP 3 ROLLD - DUP * 3 ROLLD - DUP *
+ \v/ SWAP -
\>>
\>>
REDRAW @ Draw station, target, and planets again
\<<
ERASE { #0d #0d } PVIEW DSTAT DTARG
3 NUM.P 2 +
FOR j
j DPLAN
NEXT
\>>
SENDMIS @ Send a missile
\<<
3 CF @ Outside Station Flag (clear for inside)
0 'HitSom' STO @ 0 = hit nothing
@ 1 = hit planet
@ 2 = hit target
@ 3 = hit station
@ 4 = lost in space
@ 5 = user aborted missile
@ 6 = quit program
IF MNUM 0 ==
THEN 2 CF @ Out missles, quit
ELSE
TEXT CLLCD @ Activate and clear text screen
{
{ "VIEW" \<< { #0d #0d} PVIEW WAITK DHELP \>> }
{ "REDR" \<< REDRAW DHELP \>> }
{ "SHOT" \<< TEXT CLLCD ""
IF MNUM MAX.MIS \=/
THEN
"Last Angle was " +
2 FIX ANGLE \->STR + "\010" +
END
"Input angle, push CONT" +
" 90" 3 DISP
"180 ** 0" 4 DISP
" -90" 5 DISP
3 FREEZE
PROMPT
DUP 'ANGLE' STO SETMIS DHELP \>> }
{ "CONT" CONT }
{ "GO" CONT }
{ "QUIT" \<< 2 CF 6 'HitSom' STO CONT \>> }
}
TMENU DHELP @ Display menu and help text
HALT
MNUM 1 - 'MNUM' STO @ One less missile now
{ #0d #0d } PVIEW
WHILE HitSom NOT @ Until we hit something
REPEAT UPDATE DRAWXY EVALPOS @ Calculate missle movement
END
END
\>>
SETMIS @ Set initial values for missile data, angle is on stack
\<<
NEG DUP DEG COS VINIT * 'VX' STO SIN
VINIT * 'VY' STO POSITION 1 GET OBJ\-> DROP2 'YM' STO
'XM' STO
\>>
DHELP @ Display help for temporary menu
\<<
TEXT CLLCD
"VIEW - See Planets" 1 DISP
"REDR - Redraw Screen" 2 DISP
"SHOT - Enter Angle" 3 DISP
"GO - Launch Missile" 4 DISP
"QUIT - Restore and End" 5 DISP
MNUM STD \->STR " Missle" +
IF MNUM 1 \=/ THEN "s" + END " Left" + 7 DISP
3 FREEZE
\>>
UPDATE @ Update missile position and velocity
\<< 0 0 \-> fx fy
\<<
IF XM DUP 0 < SWAP 130 > OR
YM DUP 0 < SWAP 63 > OR OR @ If off screen
THEN TIME.MAG DTIME * @ increase time interval
ELSE DTIME
END 'T' STO
3 NUM.P 2 +
FOR i @ For each planet
i CALDIST \-> x y m d @ Cal dist to missle
\<<
y YM - m * Gk * d DUP DUP * * DUP 3 ROLLD /
'fy' STO+
x XM - m * Gk * SWAP /
'fx' STO+ @ Sum resulting forces
\>>
NEXT
fx T * 'VX' STO+ fy T * 'VY' STO+ @ From total force
VX T * 'XM' STO+ VY T * 'YM' STO+ @ Find new velocity
fx DUP * fy DUP * + 'FORCE' STO @ and missile location
\>>
\>>
CALDIST @ Calculate distance from missile to center of planet
\<<
POSITION SWAP GET DUP OBJ\-> DROP2 YM - DUP * SWAP XM - DUP * + \v/
SWAP OBJ\-> DROP 4 ROLL @ Return X, Y, Mass, Distance
\>>
DRAWXY @ Draw pixel on screen for missile position
\<<
XM R\->B YM R\->B 2 \->LIST PIXON
\>>
EVALPOS @ Evaluate missile position
\<<
IF KEY @ If a key is hit, abort missile
THEN
5 'HitSom' STO
ELSE
IF DTIME TIME.MAG * T == @ If off screen
THEN
IF FORCE MIN.FORC < @ Check if lost in space
THEN 4 'HitSom' STO
END
ELSE @ Else when on screen
3 NUM.P 2 + @ Check if we hit a planet
FOR i
i CALDIST \-> x y m d
\<<
IF d m \<= THEN 1 'HitSom' STO END
\>>
NEXT
1 CALDIST @ Check if we hit the station
IF 3 FC? @ IF not outside station
THEN
IF S.SIZE 1 + > @ Are we outside yet?
THEN 3 SF @ We are now outside the station
END
ELSE @ We are outside
IF S.SIZE 1 + \<= @ did we hit ourself?
THEN 3 'HitSom' STO
END
END
2 CALDIST @ Check if we hit the target
IF T.SIZE 1 + \<= THEN 2 'HitSom' STO END
END
END
CLEAR @ Clear CALDIST stuff off stack
MESS @ Output appropriate message
\>>
MESS @ Display appropriate message
\<<
IF HitSom
THEN
TEXT CLLCD @ Display text screen and clear
CASE
HitSom 1 ==
THEN "Hit Planet"
END
HitSom 2 ==
THEN "You Hit the Target\010Using "
MAX.MIS MNUM - STD \->STR +
" Missile" +
IF MAX.MIS MNUM - 1 \=/
THEN "s" +
END
2 CF @ Stop program
END
HitSom 3 ==
THEN
"You Blew Yourself Up"
2 CF @ Stop program
END
HitSom 4 ==
THEN "Missle Escaped System"
END
HitSom 5 ==
THEN "Missle Aborted"
END
END
1 DISP
IF MNUM 0 ==
THEN
"Game Over No Missiles" 3 DISP
END
" Push any key EXCEPT" 4 DISP
" ATTN/ON to continue" 5 DISP WAITK
END
\>>
WAITK @ Wait for any key press
\<<
0 WAIT DROP
\>>
STAT GROB 7 7 C141F755F741C1 @ Station cross
TARG GROB 9 9 8300EF006C00BB10BA10BB106C00EF008300 @ Target bullseye
END