recursivebezier.py

   1
   2 from __future__ import print_function
   3
   4 import numpy as np
   5
   6 from bezier import BezierSegment
   7 from moenp import *
   8
   9 class RecursiveBezierishCurve():
  10   def __init__(db, cp, depth=10):
  11     single = BezierSegment(cp)
  12     midpoint = np.array(single.point_at_t(0.5))
  13     mid_dirn = single.point_at_t(0.5 + 0.001) - midpoint
  14     mid_dirn /= np.linalg.norm(mid_dirn)
  15     ocp_factor = 0.5
  16     mid_scale = ocp_factor * 0.5 * (np.linalg.norm(cp[1] - cp[0]) +
  17                                     np.linalg.norm(cp[3] - cp[2]))
  18     if depth > 0:
  19       constructor = lambda ccp: RecursiveBezierishCurve(ccp, depth-1)
  20     else:
  21       constructor = BezierSegment
  22
  23     db.b0 = constructor([ cp[0],
  24                           cp[1] * ocp_factor + cp[0] * (1-ocp_factor),
  25                           midpoint - mid_dirn * mid_scale,
  26                           midpoint ])
  27     db.b1 = constructor([ midpoint,
  28                           midpoint + mid_dirn * mid_scale,
  29                           cp[2] * ocp_factor + cp[3] * (1-ocp_factor),
  30                           cp[3] ])
  31   def point_at_t(db, t):
  32     if t < 0.5:
  33       return db.b0.point_at_t(t*2)
  34     else:
  35       return db.b1.point_at_t(t*2 - 1)
  36