|  The Horde | |
| |
| | Description | THE HORDE
for the Commodore 16/116/+4
Original game idea by Fabrizio Caruso
This is an action game.
You have to stop the horde of zombies that keep on advancing towards you.
If a zombie reaches the line behind you, the game is over.
CONTROLS:
- Use J L to move
- SPACE to fire a missile |
| |
| | Commented Code | VARIABLES
e(i) i-th zombie vertical position
l space character (32)
i zombie index
c arc character: with arc (41), without arrow (43)
s zombie character (40)
d arrow character (42)
y flag for arrow flying (0) or available (1)
p start player position
q player's position offset
g base address for zombie position
j score
r record
n index of zombie on the arrow trajectory
u vertical offset of zombie spawn position
EXTENDED CODE (using CBM Prg Studio notation for special characters)
0poke52,31:poke56,31:clr:s=40:dime(s):poke1177,62:fori=8to519:poke8192+i,peek(53248+i):next
1color.,1:color4,1:reada$:fori=.to31:poke8512+i,asc(mid$(a$,i+1))-1:next:poke1177,63:z=65298:vol6
2l=32:pokez+1,l:pokez,.:u=920:print"{clear}{white}j l {gray}[spc]":b=80:p=3152:g=p-b:getkeyk$:scnclr:ifj>rthenr=j
3c=41:d=42:fori=0to39:e(i)=u:pokep+i-g/3,66:pokep-s+i,64:pokeg+u+i,s:next:j=.:q=20:gosub9
4pokep+q,c:i=rnd(.)*s:h=e(i):pokeg+h+i,l:e(i)=h-s:pokeg+m+n,l:ifythenm=m+s:pokeg+m+n,d
5pokeg+e(i)+i,s:ifythenifm>=e(n)thenpokeg+e(n)+n,l:e(n)=u:j=j+1:y=.:c=41:sound3,b,2:gosub9
6geta$:ifa$<>""thena=asc(a$):pokep+q,l:k=q+(a=74)-(a=76):ifk>=.thenifk7ify=.thenifa=lthensound1,1,3:y=1:n=q:m=b:c=43:data"{25}{61}{25}{103}{154}{25}{37}{103}{21}{09}{158}{172}{75}{75}{45}{25}{21}{09}{09}{09}{09}{09}{29}{09}{01}{01}{130}{190}{67}{67}{37}{25}"
8a=.:on-(e(i)>b)goto4:char1,15,9,"{red}game over":sound3,d,s:fory=.tog:next:getkeyk$:y=.:goto2
9pokeg+m+n,l:pokeg+u+n,s:m=u+s:u=u+s*((jand63)=9):print"{home}"spc(12)"{cyan}score{white}"j" {gray}hi{light gray}"r:return
COMMENTED, EXTENDED, INDENTED CODE
0
// Lower BASIC code and vaiable top address, clear memory
poke52,31:poke56,31:clr:
// Initialization
s=40:dime(s):
// Ser read from ROM
poke1177,62:
fori=8to519:
poke8192+i,peek(53248+i):
next
1
// Set background and border color to black
color.,1:color4,1:
// Read graphics data from a single string containing editable characters (the -1 is there to avoid invalid characters)
reada$:
fori=.to31:
poke8512+i,asc(mid$(a$,i+1))-1:
next:
// Set read from RAM
poke1177,63:
// Initialization
z=65298:
// Set volume level
vol6
2
// Initialization
l=32:
// Set characters in RAM
pokez+1,l:pokez,.:
// Initialization initial zombie position
u=920:
// Display instructions
print"{clear}{white}j l {gray}[spc]":
// Initialization
b=80:p=3152:g=p-b:
// Wait for key-press
getkeyk$:
// Clear the screen
scnclr:
// Check for record and set
ifj>rthenr=j
3
// Initialization
c=41:d=42:
fori=0to39:
e(i)=u:
pokep+i-g/3,66:
pokep-s+i,64:
pokeg+u+i,s:
next:
// Set score to zero
j=.:
// Initialization
q=20:
// Display score line
gosub9
4 -- MAIN GAME LOOP
// Display player
pokep+q,c:
// Compute random zombie to move
i=rnd(.)*s:
// Delete moving zombie and update his position
h=e(i):pokeg+h+i,l:e(i)=h-s:
// Delete zombie in arrow trajectory
pokeg+m+n,l:
// If zombie is moving, then display new position
ifythen
m=m+s:pokeg+m+n,d
5
// Display moving zombie
pokeg+e(i)+i,s:
// If arrow hits a zombie
ifythenifm>=e(n)then
// Delete zombie
pokeg+e(n)+n,l:
// Reset zombie position
e(n)=u:
// Increase score
j=j+1:
// Reset flag
y=.:
// Reset arc with arrow character
c=41:
// Sound
sound3,b,2:
// Display score
gosub9
6
// Read keyboard
geta$:
// If key-press
ifa$<>""then
// Use IJKL trick (see [*])
a=asc(a$):pokep+q,l:k=q+(a=74)-(a=76):
// If new player's position is within the valid bounds, then update player's position
ifk>=.thenifk thenq=k
7
// If arrow available and key pressed is the space bar
ify=.thenifa=lthen
// Beep, set arrow as not available, set index of zombie in arrow trajectory, set arc character as arc with no arrow
sound1,1,3:y=1:n=q:m=b:c=43:
data"{25}{61}{25}{103}{154}{25}{37}{103}{21}{09}{158}{172}{75}{75}{45}{25}{21}{09}{09}{09}{09}{09}{29}{09}{01}{01}{130}{190}{67}{67}{37}{25}"
8
// Reset ASCII code of key pressed
a=.:
// If zombie not on player's line, go to line 4
on-(e(i)>b)
goto4:
// else display "GAME OVER", beep, pause, wait for key-press, set arrow as available, go back to line 2
char1,15,9,"{red}game over":sound3,d,s:fory=.tog:next:getkeyk$:y=.:goto2
9
pokeg+m+n,l:pokeg+u+n,s:m=u+s:u=u+s*((jand63)=9):print"{home}"spc(12)"{cyan}score{white}"j" {gray}hi{light gray}"r:return
[TRICK] (*)
I have come up with this trick (by myself) in 2019. It may be a new trick.
I do not use conditionals, nor precomputed offsets, nor Boolean expressions.
I use an interpolating formula that computes the offset from the ASCII code of the pressed key.
I exploit the special symmetry of the ASCII codes of the keys I J K L:
- I and K have odd codes and a distance of 2 bytes
- J and L have even codes and a distance of 2 bytes
- I and K have odd ASCII codes
- J and L have even ASCII codes
So, given s=ASC(a$) with a$ either I or J or K or L, we update the position p with
p=p+c*(21*e+1)
where
- e=s and 1 -> parity of the code, i.e., vertical vs horizontal movement
- c=s-75+e -> -1 for left/up vs +1 for right/down
- 39*e+1 -> vertical vs horizontal offset absolute value, i.e., 1 vs 40 |
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Copyright © Plus/4 World Team, 2001-2024 |
