All The Fun Of The Fair

Recreate the thrill and skill of the shooting gallery
with Jack Knight's game for the Spectrum.


The scene is a fairground booth, with a gaily striped awning at the top and a
red counter with Shooting Gallery emblazoned on it in gold. Inside, nine
light-coloured balls are bobbing up and down on air jets — and the game is to
shoot them off.

On the counter is your rifle sight, which can be moved under the air nozzle
of any ball. The pointer can be moved on the sight to represent the position
to be fired at. You're got 10 shots for your money, so take aim and fire.
Sounds easy? Try it!

You aim using the cursor keys, and use zero to fire. A counter displays the
score and high score. If you want another game, just clear the screen, and a
new game should start almost immediately.

My main problem in designing this game was how to stop a ball, once
destroyed, from reappearing. This was overcome by using DIM, and changing the
appropriately-numbered string in the PRINT statement from a ball graphic to
a blank space.

The only user-defined graphics used are for the balls and one of the five
parts of the main sight. I've converted the binary numbers to decimal to
save the tedium of BINing. The balls are GRAPHICS + A; the parts of
the rifle sight, GRAPHICS + B.


Variables
a,b,c     line positions of the balls (3 to a variable)
aa,bb,cc  allow for a, b,c to be +1 or -1
e         column position of rifle sight
g         line position of pointer
DIM q()   identifies the individual ball (for removal from game)
s         score
j         shots
k,l,m     store previous ball position for the blotting-out
d         random reversal of balls
i         avoids a series of e+l's
n,p,q     control variables
p


How it works
REM statements clearly identify the component parts
 100-220   continuously print (and blot out) the balls, reverse their
           direction at top and bottom and, where specified by RND, use
           INKEY$ to jump to sub-routines.
 400-470   count number of shots and if 10 exceeded jump program to end;
           check by ATTR whether a character space fired at is empty;
           if not there must be a ball there, so reduce the bal string to
           nil, increase the score and, if the maximum of 45, jump to the
           end routine.
 700-830   set the scene, make provision for score and high score.
1000-1800  assign variables.
1900-1920  print the rifle sight and pointer in a sub-routine to avoid
           re-printing each time the main loop is gone through.
2000-2600  create the graphics, assigning the ball to A and the part of the
           rifle sight to B.
3000-3300  at game end print comment on the score.
4000-4800  offer a new game and, if accepted, deal with high score, clear
           the screen as necessary, take the program through the variables
           and the sight and pointer re-printing, to the main loop.


Hints on conversion
There should be no problems in conversion after a study of the documentation
and the listing.

--
from Home Computing Weekly, 19th July 1983