2 from __future__ import print_function
5 from numpy import cos, sin
8 from moebdebug import dbg
12 def augment(v): return np.append(v, 1)
13 def augment0(v): return np.append(v, 0)
14 def unaugment(v): return v[0:3]
16 findcurve_subproc = None
18 class HelixishCurve():
24 dp = unit_v(cp[1]-cp[0])
25 dq = unit_v(cp[3]-cp[2])
27 dbg('HelixishCurve __init__', cp)
30 # - solve in the plane containing dP and dQ
31 # - total distance normal to that plane gives mu
32 # - now resulting curve is not parallel to dP at P
33 # nor dQ at Q, so tilt it
34 # - [[ pick as the hinge point the half of the curve
35 # with the larger s or t ]] not yet implemented
36 # - increase the other distance {t,s} by a bodge factor
37 # approx distance between {Q,P} and {Q,P}' due to hinging
38 # but minimum is 10% of (wlog) {s,t} [[ not quite like this ]]
40 dPQplane_normal = np.cross(dp, dq)
41 if (np.norm(dPQplane_normal) < 1E6):
42 dPQplane_normal += [0, 0, 1E5]
43 dPQplane_normal = unit_v(dPQplane_normal)
45 dPQplane_basis = np.column_stack(np.cross(dp, dPQplane_normal),
49 dPQplane_basis = np.vstack(dPQplane_basis, [0,0,0,1])
50 dPQplane_into = np.linalg.inv(dPQplane_basis)
52 dp_plane = unaugment(dPQplane_into * augment0(dp))
53 dq_plane = unaugment(dPQplane_into * augment0(dq))
54 q_plane = unaugment(dPQplane_into * augment(q))
55 dist_pq_plane = np.linalg.norm(q_plane)
57 # two circular arcs of equal maximum possible radius
58 # algorithm courtesy of Simon Tatham (`Railway problem',
59 # pers.comm. to ijackson@chiark 23.1.2004)
60 railway_angleoffset = atan2(*q_plane[0:1])
61 railway_theta = tau/4 - railway_angleoffset
62 railway_phi = atan2(*dq_plane[0:1]) - railway_angleoffset
63 railway_cos_theta = cos(railway_theta)
64 railway_cos_phi = cos(railway_phi)
65 if railway_cos_theta**2 + railway_cos_phi**2 > 1E6:
66 railway_roots = np.roots([
67 2 * (1 + cos(railway_theta - railway_phi)),
68 2 * (railway_cos_theta - railway_cos_phi),
71 for railway_r in railway_roots:
72 def railway_CPQ(pq, dpq):
74 return pq + railway_r * [-dpq[1], dpq[0]]
76 railway_CP = railway_CPQ([0,0,0], dp_plane)
77 railway_QP = railway_CPQ(q_plane[0:2], -dq_plane)
78 railway_midpt = 0.5 * (railway_CP + railway_QP)
81 def railway_ST(C, start, end):
83 delta = atan2(*(end - C)[0:2]) - atan2(start - C)[0:2]
86 try_s = railway_ST(railway_CP, [0,0], midpt)
87 try_t = railway_ST(railway_CP, midpt, q_plane)
88 try_st = try_s + try_t
89 if best_st is None or try_st < best_st:
94 start_mu = q_plane[2] / (start_s + start_t)
96 else: # twoarcs algorithm is not well defined
98 start_s = dist_pq_plane * .65
99 start_t = dist_pq_plane * .35
102 bodge = max( q_plane[2] * mu,
103 (start_s + start_t) * 0.1 )
104 start_s += 0.5 * bodge
105 start_t += 0.5 * bodge
110 tilt_basis = np.array([
112 0, cos(tilt), -sin(tilt), 0,
113 0, sin(tilt), cos(tilt), 0,
116 findcurve_basis = dPQplane_basis * tilt_basis
117 findcurve_into = np.linalg.inv(findcurve_basis)
119 q_findcurve = unaugment(findcurve_into, augment(q))
120 dq_findcurve = unaugment(findcurve_into, augment0(dq))
122 findcurve_target = np.concatenate(q_findcurve, dq_findcurve)
123 findcurve_start = (sqrt(start_s), sqrt(start_t), start_la,
124 start_mu, start_gamma, start_kappa)
126 findcurve_epsilon = dist_pq_plane * 0.01
128 if findcurve_subproc is None:
129 findcurve_subproc = subprocess.Popen(
132 stdin=subprocess.PIPE,
133 stdout=subprocess.PIPE,
136 restore_signals=True,
137 universal_newlines=True,
140 findcurve_input = np.hstack((findcurve_target,
142 [findcurve_epsilon])))
143 dbg('RUNNING FINDCURVE', *findcurve_input)
144 print(findcurve_subproc.stdin, *findcurve_input)
145 findcurve_subproc.stdin.flush()
148 l = findcurve_subproc.stdout.readline()
153 findcurve_result = l[0:5]
155 symbolic.get_python(something)