examples/path/springs.py

   1 # contributed by Gert-Ludwig Ingold
   2
   3 from pyx import *
   4
   5 n = 3                 # number of masses
   6 r = 3.0               # system radius
   7 rcyc = 0.3            # radius of cycloid
   8 nl = 13               # number of loops
   9 rc = 0.5              # radius of masses
  10 eps = 0.03            # extra spacing for surrounding circles
  11
  12 c = canvas.canvas()
  13 springcircle = path.circle(0, 0, r)
  14 masspositions = [i*springcircle.arclen()/n
  15                  for i in range(n)]
  16 for springsegment in springcircle.split(masspositions):
  17     c.stroke(springsegment,
  18              [deformer.cycloid(rcyc, nl),
  19               deformer.smoothed(radius=0.1)])
  20 for x, y in springcircle.at(masspositions):
  21     c.fill(path.circle(x, y, rc))
  22
  23 # draw border around springs.
  24 # In order to demonstrate another deformer, we construct
  25 # the border by expanding/constricting the original circle
  26 c.stroke(springcircle, [deformer.parallel(rc+eps)])
  27 c.stroke(springcircle, [deformer.parallel(-rc-eps)])
  28
  29 c.writeEPSfile("springs")
  30 c.writePDFfile("springs")