design/dtk/springs.py

   1 from pyx import *
   2
   3 n = 3       # number of masses
   4 r = 3.0     # system radius
   5 rcyc = 0.3  # radius of cycloid
   6 nl = 13     # number of cycloid half-loops
   7 rc = 0.5    # radius of masses
   8 eps = 0.03  # extra spacing for surrounding circles
   9
  10 c = canvas.canvas()
  11 springcircle = path.circle(0, 0, r)
  12 masspositions = [i*springcircle.arclen()/n
  13                  for i in range(n)]
  14 for springsegment in springcircle.split(masspositions):
  15     c.stroke(springsegment,
  16              [deformer.cycloid(rcyc, nl),
  17               deformer.smoothed(radius=0.1)])
  18 for x, y in springcircle.at(masspositions):
  19     c.fill(path.circle(x, y, rc))
  20 c.stroke(path.circle(0, 0, r - rc - eps))
  21 c.stroke(path.circle(0, 0, r + rc + eps))
  22 c.writeEPSfile("springs")