2D Stars Examples This is classic 2D (right to left) star scrolling routine. This version is using parallel arrays for the stars coordinate and speed. There's a bunch of ways to do this; but here we're create filling our star with a random starting coordinate within the bitmap screen as well as give this star a random speed.
This is integer only so it has fixed point precision, which just means we scale our values up by some fixed constant and anything bellow this becomes the fractional part and anything above it is the whole number part.
[pbcode]
; PROJECT : Project1
; AUTHOR :
; CREATED : 29/08/2023
; ---------------------------------------------------------------------
AccBits = 2^16
ScreenWidth =800
ScreenHeight =600
Count=25000
Dim StarsX(Count)
Dim StarsY(Count)
Dim StarsSpeed(Count)
For lp =0 to count
StarsX(lp) = rnd(ScreenWidth*AccBits)
StarsY(lp) = rnd(ScreenHEight-1)
StarsSpeed(lp) = rndrange(1*AccBits,5*AccBits)
next
// -------------------------------------------
do // Main Loop
// -------------------------------------------
cls
lockbuffer
For lp =0 to count
// Move the star to the left
x=StarsX(lp)-StarsSpeed(lp)
if X<0
// wrap the X coordinate
X=X+(ScreenWidth*AccBits)
// give this star a new Y and speed
StarsY(lp) = rnd(ScreenHEight-1)
StarsSpeed(lp) = rndrange(1*AccBits,5*AccBits)
endif
// Store the updated X
StarsX(lp)=x
// draw it to the surface
dot x/AccBits,StarsY(lp)
next
unlockbuffer
// flip the buffers
sync
loop spacekey()=true
[/pbcode]
Learn to Code:
https://PlayBASIC.com
Also see: Electric 2D Stars (https://www.youtube.com/watch?v=uRkrxVNUFM8&ab_channel=PlayBasic)