Starfield with trails

[angros47]

Very simple starfield effect, made using the old school trick of color cycling. Use PgUp and PgDown to set the speed.

Code: Select all

const w=800: const h=600

screenres w, h, 8


Dim pal(0 To 255) As Integer

dim as single x, y, c, sx, sy, sc
c=1.0

for i as integer=1 to 300
	x=w/2: y=h/2
	sx=(rnd()*2.0)-1.0
	sy=(rnd()*2.0)-1.0
	sc=rnd()
	do
		x+=sx: y+=sy: c+=sc
		if c>255.0 then c-=254.0
		pset (x,y), c
	loop until x<0 orelse x>w orelse y<0 orelse y>h

next

dim t as single
dim speed as single=.01

do
	palette using pal

	dim d as integer=&hFF0000-(speed *100)
	for i as integer=1 to 255
		if pal(i) then pal(i)=pal(i)/20*19 and &hFF0000
	next
	t= (t+speed) 
	if t>=255.0 then t-=254.0
	pal (t+.5)=&hFFFFFF

	if multikey(&h49) andalso speed <1 then speed+=.001
	if multikey(&h51) andalso speed >0.001 then speed-=.001
	'screensync
	sleep 1

loop until multikey(1)

[dafhi]

neat! had to tweak. also looks cool with the lines uncommented

Code: Select all

   var rad = .01 + 250 * rnd
   var ang = rnd * tau
   sx = cos(ang)
   sy = sin(ang)
   x=w/2 + rad * sx
   y=h/2 + rad * sy
   rad = rnd + .1
   sx *= rad
   sy *= rad
   'sx = (rnd()*2.0)-1.0
   'sy = (rnd()*2.0)-1.0

[integer]

neat! had to tweak. also looks cool with the lines uncommented

Code: Select all

   var rad = .01 + 250 * rnd
   var ang = rnd * tau
   sx = cos(ang)
   sy = sin(ang)
   x=w/2 + rad * sx
   y=h/2 + rad * sy
   rad = rnd + .1
   sx *= rad
   sy *= rad
   'sx = (rnd()*2.0)-1.0
   'sy = (rnd()*2.0)-1.0

Just curious.
What is your initial value for "tau"?

[angros47]

tau is a math constant: it is equal to 2*pi, or 6.28318530718