A 3d tunnel effect.
Code:
' sleepy_tunnel.n7
' ----------------
#win32
constant WIN_W = 640, WIN_H = 480
set window "Sleepy Tunnel", WIN_W, WIN_H
set redraw off
aa = 0
while not keydown(KEY_ESCAPE, true)
aa = aa + 0.05
zoffset = (zoffset + 0.001)%0.01
set color 0, 0, 0
cls
set color 255, 255, 255
maxz = 0.1 + 150*0.01
for i = 150 to 0
z = 0.1 + i*0.01 - zoffset
s = 50/z
x = cos(z*5 + aa)*(z - 0.1)*50
y = sin(z*5 + aa)*(z - 0.1)*25
intens = 255 - 255*z*1.5/maxz
set color intens*0.5, intens, intens*0.75
draw pixel WIN_W/2 + x/z + cos(rad(0))*s, WIN_H/2 + y/z + sin(rad(0))*s
a = 15
while a <= 360
draw line to WIN_W/2 + x/z + cos(rad(a))*s, WIN_H/2 + y/z + sin(rad(a))*s
a = a + 15
wend
next
redraw
fwait 60
wend