# colorw.py3   color wheel based on phase angle
#              copied from 1/1/97 JSS initial version
#              may be run using  python colorw.py3
import tkinter
import math

top = tkinter.Tk()
C = tkinter.Canvas(top, bg="white", width=400, height=400)
top.title('colorw.py3')
Pi = 3.14159265358979323846
radius_1 = 160.0
radius_2 =  60.0
cnt = 0
xc = 200.0
yc = 210.0

A = -1.0
while(A < 1.0):  # walk the angle in bams around the circle 
         # A = arctan(Y, X)/PI   for normalized angle from X-Y plot
         # get double R,G,B  R==1 at A==0, G==1 at A==2/3, B==1 at A==-2/3 
  R = 1.0 - abs(A)
  AA = A - 2.0/3.0
  if(AA < -1.0):
    AA = 2.0+AA

  G = 1.0 - abs(AA)
  AA = A + 2.0/3.0
  if(AA > 1.0):
    AA = 2.0-AA

  B = 1.0 - abs(AA)

  # boost low end and normalize (this brightens colors) 
  R = R+0.2
  G = G+0.2
  B = B+0.2
  AAA = max(R, G)
  AAA = max(AAA, B)
  R = R/AAA
  G = G/AAA
  B = B/AAA
    
  # compute line ends 
  x1 = radius_1 * math.cos(A * Pi)
  y1 = radius_1 * math.sin(A * Pi)
  x2 = radius_2 * math.cos(A * Pi)
  y2 = radius_2 * math.sin(A * Pi)
  A = A + 0.01  # 240 lines, 0.01  200 lines -1.0 to 1.0 

  rh = hex(int(255*R))
  gh = hex(int(255*G))
  bh = hex(int(255*B))
  color = "#" + rh[2:] + gh[2:] + bh[2:]
  line = C.create_line(xc+x1, yc+y1, xc+x2, yc+y2, width=5, fill=color)

# end while
C.pack()
top.mainloop()