The best way to do that is to make the sprites before-hand. Try this outside of the main loop:
for blast=1 to 4
sprite blast,320,-41,1
hide sprite blast
next blast
max=2000
DIM blast_y(max)
DIM blast_x(max)
speed=15
gun_cool=0
blast = 1
Then you test for the fire-key press using a code similar to this:
if spacekey()=1 and gun_cool=0
show sprite blast
blast_y(plasma)=player_y-16
blast_x(plasma)=player_x+5
sprite blast,blast_x(plasma),blast_y(plasma),8
gun_cool=10
blast=blast+1
if blast=5 then blast=1
endif
Then you handle the blasts like this:
rem handle blasts
for number=1 to 5
if blast_y(number) > -40
blast_y(number) = blast_y(number)-speed
sprite number,blast_x(number),blast_y(number),8
endif
if blast_y(number) < -40
hide sprite number
endif
next number
hope that helps. I know that only handles 5 blasts at a time, but that can be changed easily as well as the speed and gun-cool rate.
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