-
Notifications
You must be signed in to change notification settings - Fork 0
/
ParametricHull.py
276 lines (233 loc) · 10 KB
/
ParametricHull.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
import FreeCAD, FreeCADGui, os, Part, scipy.optimize
import numpy as np
ui_path = os.path.join(os.path.dirname(__file__), 'parametric-hulls.ui')
def ft(m):
return m * 1000 / 25.4 / 12
def td(m, n):
def func(x):
return (1 - x ** 2) ** m * ((1 - x) / 2) ** (n / 2)
return func
def td_max(m, n):
return -n / (-n + 4*m)
def td_inv(f, y, centre, endpoint = 1):
step = endpoint - centre
x = centre
while abs(y - f(x)) > 1e-6:
step /= 2
direction = np.sign(f(x) - y)
x += direction * step
return x
def spline_from_vertices(vs):
# spline = Part.BSplineCurve()
# spline.buildFromPoles(vs)
# return spline
spline = Part.BSplineCurve()
spline.interpolate(vs)
return spline
def parabolic_sheer(x, teardrop_y_func, centre, rise, sheer_y):
"""Calculate the z-coordinates of the sheer line.
The sheer line is constructed by the following method:
From the point of maximum beam forward to the bow, the sheer line
is a parabola, fitted through these two points and with the
maximum beam at the parabola's minimum.
From the point of maximum beam aft to the sterm, the sheer line is
constructed so that fore-aft deck beams running parallel to the
centreline are horizontal. This makes the deck easy to construct,
easier to walk on and gives it a more traditional, 'shippy' look.
Mathematically, to construct the rear half of the sheer line's
z-coordinates, we start with that point's x,y coordinates. We
then find the x-coordinate forward of the maximum beam which has
the same y-coordinate as the point we're trying to construct and
use that point's z-coordinate as the z-coordinate of the point
we're constructing.
Or, put another way, "points on the sheer that have equal
y-coordinates also have equal z-coordinates".
"""
# The forward half is a parabola.
p = 1.
q = centre * 2. - 1.
sheer_z = np.array([0.] * len(x))
ps = (x >= centre)
def z_func(x):
return (x - p) * (x - q)
sheer_z[ps] = z_func(x[ps])
# The aft half is constructed from the forward half.
nps = ~ps
indices = np.array(range(len(x)))
for ii, xp, y in zip(indices[nps], x[nps], sheer_y[nps]):
# We know the stern is at the same elevation as the bow without doing
# any fancy maths
if ii == 0:
sheer_z[ii] = sheer_z[-1]
continue
if ii == len(x)-1:
sheer_z[ii] = sheer_z[0]
continue
opposite_x = td_inv(teardrop_y_func, y, centre)
sheer_z[ii] = z_func(opposite_x)
# Scaled to the correct fall at maximum beam.
sheer_z *= -rise / ((centre - p) * (centre - q))
return sheer_z
class ParametricHullPanel():
def __init__(self):
self.form = FreeCADGui.PySideUic.loadUi(ui_path)
self.left = self.create_objects('left')
self.right = self.create_objects('right')
dev = 0.2
self.set_deviation(self.left, dev)
self.set_deviation(self.right, dev)
self.update_ft()
self.form.length.valueChanged.connect(self.update_ft)
self.form.beam.valueChanged.connect(self.update_ft)
self.form.draft.valueChanged.connect(self.update_ft)
self.form.freeboard.valueChanged.connect(self.update_ft)
self.form.stations.valueChanged.connect(self.update)
self.form.h_box.valueChanged.connect(self.update)
self.form.v_box.valueChanged.connect(self.update)
self.form.l_box.valueChanged.connect(self.update)
self.form.teardrop.valueChanged.connect(self.update)
self.form.sheer_rise.valueChanged.connect(self.update)
def create_objects(self, suf):
return dict(
feature=FreeCAD.ActiveDocument.addObject('Part::Feature', 'boundary' + suf),
stations=FreeCAD.ActiveDocument.addObject('Part::Feature', 'stations' + suf),
beams=FreeCAD.ActiveDocument.addObject('Part::Feature', 'beams' + suf),
surface=FreeCAD.ActiveDocument.addObject('Surface::Filling', 'surface' + suf),
deck=FreeCAD.ActiveDocument.addObject("Surface::Filling", "deck" + suf)
)
def set_deviation(self, d, dev = 0.01):
for k, v in d.iteritems():
v.ViewObject.Deviation = dev
def update_ft(self, *args):
length = self.form.length.value()
self.form.length_ft.setValue(ft(length))
beam = self.form.beam.value()
self.form.beam_ft.setValue(ft(beam))
draft = self.form.draft.value()
self.form.draft_ft.setValue(ft(draft))
freeboard = self.form.freeboard.value()
self.form.freeboard_ft.setValue(ft(freeboard))
self.update()
def update(self, *args):
lod = self.form.length.value()
n_stations = self.form.stations.value()
n_points = self.form.control_points.value()
h_box = self.form.h_box.value()
v_box = self.form.v_box.value()
l_box = self.form.l_box.value()
beam = self.form.beam.value()
draft = self.form.draft.value()
freeboard = self.form.freeboard.value()
sheer_rise = self.form.sheer_rise.value()
teardrop_factor = self.form.teardrop.value()
self.create_geometry(1, lod, n_stations, n_points, h_box, v_box, l_box,
beam, draft, freeboard, sheer_rise, teardrop_factor,
self.left)
self.create_geometry(-1, lod, n_stations, n_points, h_box, v_box, l_box,
beam, draft, freeboard, sheer_rise, teardrop_factor,
self.right)
def create_geometry(self, direction, lod, n_stations, n_points, h_box, v_box, l_box,
beam, draft, freeboard, sheer_rise, teardrop_factor,
side):
feature = side['feature']
stations = side['stations']
beams = side['beams']
surface = side['surface']
deck = side['deck']
# Convert dimensions to mm
lod *= 1000
sheer_rise *= 1000
# TODO: other dimensions
# Generate normalised geometry on the domain [-1, 1]
print('Basic geom')
x = np.arange(-1, 1.00001, 2 / (n_stations + 1.0))
sheer_y_func = td(h_box, teardrop_factor)
sheer_y_norm = sheer_y_func(x)
norm_beam = max(sheer_y_norm)
rabbet_z_func = td(v_box, teardrop_factor)
rabbet_z = -rabbet_z_func(x)
norm_rabbet = max(abs(rabbet_z))
rabbet_z *= (draft + freeboard) * 1000 / norm_rabbet
beam_max = td_max(h_box, teardrop_factor)
sheer_z = parabolic_sheer(x, sheer_y_func, beam_max, sheer_rise, sheer_y_norm)
sheer_y = sheer_y_norm * (beam / 2) * 1000 / norm_beam * direction
rabbet_z[0] = sheer_z[0]
rabbet_z[-1] = sheer_z[-1]
ps = (x > beam_max)
# Now convert the x co-ordinates to the domain [0, lod]
x += 1
x *= lod / 2
# Now generate ribs at each design station
print('stations')
stations_geom = []
for ii, a in enumerate(x):
station = [FreeCAD.Vector(a, sheer_y[ii], sheer_z[ii])]
for jj in range(n_points):
angle = np.pi / 2 / (n_points + 1) * (jj + 1)
v = FreeCAD.Vector(
a,
np.cos(angle) * sheer_y[ii],
#np.sin(angle)**v_box * np.sin(angle / 2)**teardrop_factor * rabbet_z[ii])
np.sin(angle)**l_box * rabbet_z[ii])
station.append(v)
station.append(FreeCAD.Vector(
a, 0, rabbet_z[ii]
))
stations_geom.append(station)
print('Splines')
boundary = [
spline_from_vertices([FreeCAD.Vector(a, b, c) for a, b, c in zip(x, sheer_y, sheer_z)]),
spline_from_vertices([FreeCAD.Vector(a, 0, b) for a, b in zip(x, rabbet_z)])
]
# At either end, the "curves" resolve to a single point and so can't be interpolated
station_curves = [spline_from_vertices(l) for l in stations_geom[1:-1]]
print('beams')
beams_geom = []
for px, ny, py, pz in zip(x[ps], sheer_y_norm[ps], sheer_y[ps], sheer_z[ps]):
if px == 0:
opx = 1
else:
opx = td_inv(sheer_y_func, ny, beam_max, -1)
opposite_x = (opx + 1) * lod / 2
print(px, py, pz, opx, opposite_x)
beams_geom.append(spline_from_vertices([FreeCAD.Vector(px, py, pz), FreeCAD.Vector(opposite_x, py, pz)]))
print('Shapes')
shape_lines = [p.toShape() for p in boundary]
station_lines = [p.toShape() for p in station_curves]
beam_lines = [p.toShape() for p in beams_geom]
print('Parts')
feature.Shape = Part.makeCompound(shape_lines)
stations.Shape = Part.makeCompound(station_lines)
beams.Shape = Part.makeCompound(beam_lines)
FreeCAD.ActiveDocument.recompute()
print('Surfaces')
surface.BoundaryEdges = [
(feature, ['Edge{}'.format(ii+1) for ii in range(len(boundary))])
]
surface.UnboundEdges = [
(stations, ['Edge{}'.format(ii+1) for ii in range(len(station_lines))])
]
surface.recompute()
deck.BoundaryEdges = [
(feature, ["Edge1"]),
(beams, ["Edge{}".format(len(beam_lines))])
]
deck.UnboundEdges = [
(beams, ["Edge{}".format(ii + 1) for ii in range(1, len(beam_lines)-1)])
]
deck.recompute()
# self.surface.recomputeFeature()
def accept(self):
return True
class CmdParametricHull():
def __init__(self):
self.panel = None
def Activated(self):
self.panel = ParametricHullPanel()
FreeCADGui.Control.showDialog(self.panel)
def IsActive(self):
return FreeCAD.ActiveDocument is not None
def GetResources(self):
return { 'Pixmap': ':/icons/Hull.svg',
'MenuText': 'Generate Hull',
'ToolTip': 'Generate parametric hull' }