unwinding color spiral

[tsh73]

I dunno
It started from the idea of creating a dot and increase radius from center
Like, how many will be fast enough
Then it turned out to be spiral
Then it turned out to be rotating spiral
Then it picked up color

EDIT
try to change
       #gr "circlefilled 10"
to
       #gr "circlefilled ";2+r/cx*10




nomainwin
global QuitRequested

open "emitting color circles" for graphics_nsb_nf as #gr
#gr "home; down; posxy cx cy"
#gr "trapclose [quit]"

N=40    'looks OK for my (slow) machine. Try to change
pi=acs(-1)
#gr "color white"
#gr "backcolor red"
while 1
   for i = 1 to N
       SCAN
       a=3*2*pi*i/N
       r=i/N*cx*1.2
       x=r*cos(a+a0)
       y=r*sin(a+a0)
       #gr "place ";cx+x;" ";cy+y
       #gr "backcolor ";rainbow$(((a+a0) mod pi) / pi)
       #gr "circlefilled 10"
   next
   a0=a0-3*2*pi/N
   call pause 30
   if  QuitRequested then [quit]
   #gr "cls"
wend


wait

[quit]
   timer 0
   close #gr
   end

sub pause mil    'now after pause you can check if QuitRequested
   t=time$("ms")
   while time$("ms")<t+mil
       scan
   wend
   exit sub
[quit]
    QuitRequested=1
end sub

function rainbow$(x)
   hi = int((x*6) mod 6)+ 5*(x<0)  'fixed to 0..5
   f = (x*6) mod 1 + (x<0)         'frac, 0..1
   q = (1-f)
   select case hi
   case 0
       r = 1: g = f: b = 0
   case 1
       r = q: g = 1: b = 0
   case 2
       r = 0: g = 1: b = f
   case 3
       r = 0: g = q: b = 1
   case 4
       r = f: g = 0: b = 1
   case 5
       r = 1: g = 0: b = q
   end select
   R = int(r*255)
   G = int(g*255)
   B = int(b*255)
   rainbow$= R;" ";G;" ";B
end function


[plus]

A little mod to sweeten the eye candy ;-))
nomainwin
global QuitRequested

open "emitting color circles" for graphics_nsb_nf as #gr
#gr "home; down; posxy cx cy"
#gr "trapclose [quit]"

N=90    'looks OK for my (slow) machine. Try to change
pi=acs(-1)
#gr "color white"
#gr "backcolor red"
while 1
   for i = 1 to N
       SCAN
       a=3*2*pi*i/N
       r=i/N*cx*1.2
       x=r*cos(a+a0)
       y=r*sin(a+a0)
       #gr "place ";cx+x;" ";cy+y
       for radius = 34 to 4 step -4
           #gr "color ";rainbow$(((a+a0+radius) mod pi) / .5*pi)
           #gr "backcolor ";rainbow$(((a+a0+radius) mod pi) / pi)
           #gr "circlefilled ";radius
       next
   next
   a0=a0-3*2*pi/N
   call pause 20
   if  QuitRequested then [quit]
   '#gr "cls"
wend


wait

[quit]
   timer 0
   close #gr
   end

sub pause mil    'now after pause you can check if QuitRequested
   t=time$("ms")
   while time$("ms")<t+mil
       scan
   wend
   exit sub
[quit]
    QuitRequested=1
end sub

function rainbow$(x)
   hi = int((x*6) mod 6)+ 5*(x<0)  'fixed to 0..5
   f = (x*6) mod 1 + (x<0)         'frac, 0..1
   q = (1-f)
   select case hi
   case 0
       r = 1: g = f: b = 0
   case 1
       r = q: g = 1: b = 0
   case 2
       r = 0: g = 1: b = f
   case 3
       r = 0: g = q: b = 1
   case 4
       r = f: g = 0: b = 1
   case 5
       r = 1: g = 0: b = q
   end select
   R = int(r*255)
   G = int(g*255)
   B = int(b*255)
   rainbow$= R;" ";G;" ";B
end function


b = b + ...