def fill(self):
"""Fill the surface inside the polygon with triangles.
Returns a TriSurface filling the surface inside the polygon.
"""
print("AREA(self) %s" % self.area())
# creating elems array at once (more efficient than appending)
from gui.draw import draw, pause, undraw
from geomtools import insideTriangle
x = self.coords
n = x.shape[0]
tri = -ones((n - 2, 3), dtype=Int)
# compute all internal angles
e = arange(x.shape[0])
c = self.internalAngles()
# loop in order of smallest angles
itri = 0
while n > 3:
#print("ANGLES",c)
# try minimal angle
srt = c.argsort()
for j in srt:
#print("ANGLE: %s" % c[j])
if c[j] > 180.:
print(
"OOPS, I GOT STUCK!\nMaybe the curve is self-intersecting?"
)
#print("Remaining points: %s" % e)
#raise
#
# We could return here also the remaining part
#
return TriSurface(x, tri[:itri])
i = (j - 1) % n
k = (j + 1) % n
newtri = [e[i], e[j], e[k]]
# remove the point j of triangle i,j,k
# recompute adjacent angles of edge i,k
ii = (i - 1) % n
kk = (k + 1) % n
iq = e[[ii, i, k, kk]]
PQ = Polygon(x[iq])
cn = PQ.internalAngles()
cnew = cn[1:3]
reme = roll(e, -j)[2:-1]
T = x[newtri].reshape(1, 3, 3)
P = x[reme].reshape(-1, 1, 3)
check = insideTriangle(T, P)
if not check.any():
# Triangle is ok
break
#draw(TriSurface(x,newtri),bbox='last',color='red')
# accept new triangle
tri[itri] = newtri
c = roll(concatenate([cnew, roll(c, 1 - j)[3:]]), j - 1)
e = roll(roll(e, -j)[1:], j)
n -= 1
itri += 1
tri[itri] = e
return TriSurface(x, tri)
def run():
reset()
smooth()
lights(True)
S = TriSurface.read(getcfg('datadir')+'/horse.off')
SA = draw(S)
res = askItems([
('direction',[1.,0.,0.]),
('number of sections',20),
('color','red'),
('ontop',False),
('remove surface',False),
])
if not res:
return
d = res['direction']
n = res['number of sections']
c = res['color']
slices = S.slice(dir=d,nplanes=n)
linewidth(2)
draw(slices,color=c,view=None,bbox='last',nolight=True,ontop=res['ontop'])
export({'_HorseSlice_slices':slices})
if res['remove surface']:
undraw(SA)
zoomAll()
def remesh(self, edgelen=None):
"""Remesh a TriSurface.
edgelen is the suggested edge length
"""
if edgelen is None:
self.getElemEdges()
E = Mesh(self.coords, self.edges, eltype='line2')
edgelen = E.lengths().mean()
tmp = utils.tempFile(suffix='.stl').name
tmp1 = utils.tempFile(suffix='.stl').name
pf.message("Writing temp file %s" % tmp)
self.write(tmp, 'stl')
pf.message("Remeshing using VMTK (edge length = %s)" % edgelen)
cmd = "vmtk vmtksurfaceremeshing -ifile %s -ofile %s -edgelength %s" % (
tmp, tmp1, edgelen)
sta, out = utils.runCommand(cmd)
os.remove(tmp)
if sta:
pf.message("An error occurred during the remeshing.")
pf.message(out)
return None
S = TriSurface.read(tmp1)
os.remove(tmp1)
return S
def run():
global F, G
clear()
smooth()
view('iso')
F = cylinder(L=8., D=2., nt=36, nl=20, diag='u').centered()
F = TriSurface(F).setProp(3).close(method='planar').fixNormals()
G = F.rotate(90., 0).trl(0, 1.).setProp(1)
export({'F': F, 'G': G})
draw([F, G])
res = askItems([
_I('op',
text='Operation',
choices=[
'+ (Union)',
'- (Difference)',
'* Intersection',
'Intersection Curve',
],
itemtype='vradio'),
_I('verbose', False, text='Show stats'),
])
if not res:
return
op = res['op'][0]
verbose = res['verbose']
if op in '+-*':
I = F.boolean(G, op, verbose=verbose)
else:
I = F.intersection(G, verbose=verbose)
clear()
draw(I)
if op in '+-*':
return
else:
if ack('Create a surface inside the curve ?'):
I = I.toMesh()
e = connectedLineElems(I.elems)
I = Mesh(I.coords, connectedLineElems(I.elems)[0])
clear()
draw(I, color=red, linewidth=3)
S = fillBorder(I, method='planar')
draw(S)
def delaunay(X):
"""Return a Delaunay triangulation of the specified Coords.
While the Coords are 3d, only the first 2 components are used.
Returns a TriSurface with the Delaunay trinagulation in the x-y plane.
"""
from voronoi import voronoi
return TriSurface(X, voronoi(X[:, :2]).triangles)
def run():
global F,G
clear()
smooth()
view('iso')
F = cylinder(L=8.,D=2.,nt=36,nl=20,diag='u').centered()
F = TriSurface(F).setProp(3).close(method='planar').fixNormals()
G = F.rotate(90.,0).trl(0,1.).setProp(1)
export({'F':F,'G':G})
draw([F,G])
res = askItems(
[ _I('op',text='Operation',choices=[
'+ (Union)',
'- (Difference)',
'* Intersection',
'Intersection Curve',
],itemtype='vradio'),
_I('verbose',False,text='Show stats'),
])
if not res:
return
op = res['op'][0]
verbose = res['verbose']
if op in '+-*':
I = F.boolean(G,op,verbose=verbose)
else:
I = F.intersection(G,verbose=verbose)
clear()
draw(I)
if op in '+-*':
return
else:
if ack('Create a surface inside the curve ?'):
I = I.toMesh()
e = connectedLineElems(I.elems)
I = Mesh(I.coords,connectedLineElems(I.elems)[0])
clear()
draw(I,color=red,linewidth=3)
S = fillBorder(I,method='planar')
draw(S)
def smallestDirection(x,method='inertia',return_size=False):
"""Return the direction of the smallest dimension of a Coords
- `x`: a Coords-like array
- `method`: one of 'inertia' or 'random'
- return_size: if True and `method` is 'inertia', a tuple of a direction
vector and the size along that direction and the cross directions;
else, only return the direction vector.
"""
x = x.reshape(-1,3)
if method == 'inertia':
# The idea is to take the smallest dimension in a coordinate
# system aligned with the global axes.
C,r,Ip,I = x.inertia()
X = x.trl(-C).rot(r)
sizes = X.sizes()
i = sizes.argmin()
# r gives the directions as column vectors!
# TODO: maybe we should change that
N = r[:,i]
if return_size:
return N,sizes[i]
else:
return N
elif method == 'random':
# Take the mean of the normals on randomly created triangles
from plugins.trisurface import TriSurface
n = x.shape[0]
m = 3 * (n // 3)
e = arange(m)
random.shuffle(e)
if n > m:
e = concatenate([e,[0,1,n-1]])
el = e[-3:]
S = TriSurface(x,e.reshape(-1,3))
A,N = S.areaNormals()
ok = where(isnan(N).sum(axis=1) == 0)[0]
N = N[ok]
N = N*N
N = N.mean(axis=0)
N = sqrt(N)
N = normalize(N)
return N
def run():
reset()
smooth()
lights(True)
S = TriSurface.read(getcfg('datadir') + '/horse.off')
SA = draw(S)
bb = S.bbox()
bb1 = [1.1 * bb[0] - 0.1 * bb[1], 1.1 * bb[1] - 0.1 * bb[0]]
print(bb)
print(bb1)
res = askItems([
_I('Resolution', 100),
])
if not res:
return
nmax = res['Resolution']
sz = bb1[1] - bb1[0]
step = sz.max() / (nmax - 1)
n = (sz / step).astype(Int)
print(n)
P = Formex(simple.regularGrid(bb1[0], bb1[0] + n * step, n).reshape(-1, 3))
draw(P, marksize=1, color='black')
#drawNumbers(P)
zoomAll()
ind = S.inside(P)
vox = zeros(n + 1, dtype=uint8)
print(vox.shape)
vox1 = vox.reshape(-1)
print(vox1.shape, ind.max())
vox1[ind] = 1
print(vox.max())
P.setProp(vox1)
draw(P, marksize=8)
dirname = askDirname()
chdir(dirname)
# Create output file
if not checkWorkdir():
print("Could not open a directory for writing. I have to stop here")
return
fs = utils.NameSequence('horse', '.png')
clear()
flat()
A = None
for frame in vox:
B = showGreyImage(frame)
saveBinaryImage(frame * 255, fs.next())
undraw(A)
A = B
def run():
reset()
smooth()
lights(True)
S = TriSurface.read(getcfg('datadir')+'/horse.off')
SA = draw(S)
bb = S.bbox()
bb1 = [ 1.1*bb[0]-0.1*bb[1], 1.1*bb[1]-0.1*bb[0]]
print(bb)
print(bb1)
res = askItems([
_I('Resolution',100),
])
if not res:
return
nmax = res['Resolution']
sz = bb1[1]-bb1[0]
step = sz.max() / (nmax-1)
n = (sz / step).astype(Int)
print(n)
P = Formex(simple.regularGrid(bb1[0],bb1[0]+n*step,n).reshape(-1,3))
draw(P, marksize=1, color='black')
#drawNumbers(P)
zoomAll()
ind = S.inside(P)
vox = zeros(n+1,dtype=uint8)
print(vox.shape)
vox1 = vox.reshape(-1)
print(vox1.shape,ind.max())
vox1[ind] = 1
print(vox.max())
P.setProp(vox1)
draw(P, marksize=8)
dirname = askDirname()
chdir(dirname)
# Create output file
if not checkWorkdir():
print("Could not open a directory for writing. I have to stop here")
return
fs = utils.NameSequence('horse','.png')
clear()
flat()
A = None
for frame in vox:
B = showGreyImage(frame)
saveBinaryImage(frame*255,fs.next())
undraw(A)
A = B
def sphere(ndiv=6):
"""Create a triangulated spherical surface.
A high quality approximation of a spherical surface is constructed as
follows. First an icosahedron is constructed. Its triangular facets are
subdivided by dividing all edges in `ndiv` parts. The resulting mesh is
then projected on a sphere with unit radius. The higher `ndiv` is taken,
the better the approximation. `ndiv=1` results in an icosahedron.
Returns:
A TriSurface, representing a triangulated approximation of a
spherical surface with radius 1 and center at the origin.
"""
from elements import Icosa
from plugins.trisurface import TriSurface
M = TriSurface(Icosa.vertices,Icosa.faces)
M = M.subdivide(ndiv).fuse()
M = M.projectOnSphere()
return M
def run():
reset()
smooth()
lights(True)
transparent(False)
setView('horse', [20, 20, 0])
S = TriSurface.read(getcfg('datadir') + '/horse.off')
bb = S.bbox()
t = -0.3
bb[0] = (1.0 - t) * bb[0] + t * bb[1]
draw(S, bbox=bb, view='front')
try:
P, n, t = askSlices(S.bbox())
except:
return
a = t / len(P)
F = S.toFormex()
G = []
old = seterr(all='ignore')
setDrawOptions({'bbox': None})
clear()
A = None
for i, p in enumerate(P):
F1, F = F.cutWithPlane(p, -n)
if F1.nelems() > 0:
F1.setProp(i)
G = [g.rot(a, around=p) for g in G]
G.append(F1)
#clear()
B = draw([F, G])
if A:
undraw(A)
A = B
seterr(**old)
x = pf.canvas.width() / 2
y = pf.canvas.height() - 40
T = drawText("No animals got hurt during the making of this movie!",
x,
y,
size=18,
gravity='C')
for i in range(10):
sleep(0.3)
undecorate(T)
sleep(0.3)
decorate(T)
def run():
reset()
smooth()
lights(True)
transparent(False)
setView('horse',[20,20,0])
S = TriSurface.read(getcfg('datadir')+'/horse.off')
bb = S.bbox()
t = -0.3
bb[0] = (1.0-t)*bb[0] + t*bb[1]
draw(S,bbox=bb,view='front')
try:
P,n,t = askSlices(S.bbox())
except:
return
a = t/len(P)
F = S.toFormex()
G = []
old = seterr(all='ignore')
setDrawOptions({'bbox':None})
clear()
A = None
for i,p in enumerate(P):
F1,F = F.cutWithPlane(p,-n)
if F1.nelems() > 0:
F1.setProp(i)
G = [ g.rot(a,around=p) for g in G ]
G.append(F1)
#clear()
B = draw([F,G])
if A:
undraw(A)
A = B
seterr(**old)
x = pf.canvas.width()/2
y = pf.canvas.height() - 40
T = drawText("No animals got hurt during the making of this movie!",x,y,size=18,gravity='C')
for i in range(10):
sleep(0.3)
undecorate(T)
sleep(0.3)
decorate(T)
def gtsset(self,
surf,
op,
filt='',
ext='.tmp',
curve=False,
check=False,
verbose=False):
"""_Perform the boolean/intersection methods.
See the boolean/intersection methods for more info.
Parameters not explained there:
- filt: a filter command to be executed on the gtsset output
- ext: extension of the result file
- curve: if True, an intersection curve is computed, else the surface.
Returns the name of the (temporary) results file.
"""
op = {'+': 'union', '-': 'diff', '*': 'inter'}[op]
options = ''
if curve:
options += '-i'
if check:
options += ' -s'
if not verbose:
options += ' -v'
tmp = utils.tempFile(suffix='.gts').name
tmp1 = utils.tempFile(suffix='.gts').name
tmp2 = utils.tempFile(suffix=ext).name
pf.message("Writing temp file %s" % tmp)
self.write(tmp, 'gts')
pf.message("Writing temp file %s" % tmp1)
surf.write(tmp1, 'gts')
pf.message("Performing boolean operation")
cmd = "gtsset %s %s %s %s %s > %s" % (options, op, tmp, tmp1, filt, tmp2)
sta, out = utils.runCommand(cmd)
os.remove(tmp)
os.remove(tmp1)
if sta or verbose:
pf.message(out)
pf.message("Reading result from %s" % tmp2)
if curve:
res = read_gts_intersectioncurve(tmp2)
else:
res = TriSurface.read(tmp2)
os.remove(tmp2)
return res
def gtsset(self,surf,op,filt='',ext='.tmp',curve=False,check=False,verbose=False):
"""_Perform the boolean/intersection methods.
See the boolean/intersection methods for more info.
Parameters not explained there:
- filt: a filter command to be executed on the gtsset output
- ext: extension of the result file
- curve: if True, an intersection curve is computed, else the surface.
Returns the name of the (temporary) results file.
"""
op = {'+':'union', '-':'diff', '*':'inter'}[op]
options = ''
if curve:
options += '-i'
if check:
options += ' -s'
if not verbose:
options += ' -v'
tmp = utils.tempFile(suffix='.gts').name
tmp1 = utils.tempFile(suffix='.gts').name
tmp2 = utils.tempFile(suffix=ext).name
pf.message("Writing temp file %s" % tmp)
self.write(tmp,'gts')
pf.message("Writing temp file %s" % tmp1)
surf.write(tmp1,'gts')
pf.message("Performing boolean operation")
cmd = "gtsset %s %s %s %s %s > %s" % (options,op,tmp,tmp1,filt,tmp2)
sta,out = utils.runCommand(cmd)
os.remove(tmp)
os.remove(tmp1)
if sta or verbose:
pf.message(out)
pf.message("Reading result from %s" % tmp2)
if curve:
res = read_gts_intersectioncurve(tmp2)
else:
res = TriSurface.read(tmp2)
os.remove(tmp2)
return res
def run():
reset()
smooth()
lights(True)
S = TriSurface.read(getcfg('datadir') + '/horse.off')
SA = draw(S)
res = askItems([
('direction', [1., 0., 0.]),
('number of sections', 20),
('color', 'red'),
('ontop', False),
('remove surface', False),
])
if not res:
return
d = res['direction']
n = res['number of sections']
c = res['color']
slices = S.slice(dir=d, nplanes=n)
linewidth(2)
draw(slices,
color=c,
view=None,
bbox='last',
nolight=True,
ontop=res['ontop'])
export({'_HorseSlice_slices': slices})
if res['remove surface']:
undraw(SA)
zoomAll()
def remesh(self,edgelen=None):
"""Remesh a TriSurface.
edgelen is the suggested edge length
"""
if edgelen is None:
self.getElemEdges()
E = Mesh(self.coords,self.edges,eltype='line2')
edgelen = E.lengths().mean()
tmp = utils.tempFile(suffix='.stl').name
tmp1 = utils.tempFile(suffix='.stl').name
pf.message("Writing temp file %s" % tmp)
self.write(tmp,'stl')
pf.message("Remeshing using VMTK (edge length = %s)" % edgelen)
cmd = "vmtk vmtksurfaceremeshing -ifile %s -ofile %s -edgelength %s" % (tmp,tmp1,edgelen)
sta,out = utils.runCommand(cmd)
os.remove(tmp)
if sta:
pf.message("An error occurred during the remeshing.")
pf.message(out)
return None
S = TriSurface.read(tmp1)
os.remove(tmp1)
return S
totalrot = res['total rot']
xmin,xmax = bb[:,axis]
dx = (xmax-xmin) / nslices
x = arange(nslices+1) * dx
N = unitVector(axis)
P = [ bb[0]+N*s for s in x ]
return P,N,totalrot
else:
return None
reset()
smooth()
lights(True)
transparent(False)
setView('horse',[20,20,0])
S = TriSurface.read(getcfg('datadir')+'/horse.off')
bb = S.bbox()
t = -0.3
bb[0] = (1.0-t)*bb[0] + t*bb[1]
draw(S,bbox=bb,view='front')
try:
P,n,t = askSlices(S.bbox())
except:
exit()
a = t/len(P)
F = S.toFormex()
G = []
def drawSurf(F, surface=False, **kargs):
"""Draw a Formex as surface or not."""
if surface:
F = TriSurface(F)
return draw(F, **kargs)
sw=sp[w]
return px[sw], w, itx[sw], delete( arange(len(segm)), w)
else:return px, ilx, itx
clear()
smooth()
lights(True)
transparent(False)
view('iso')
image = None
scaled_image = None
# read the teapot surface
T = TriSurface.read(getcfg('datadir')+'/teapot.off')
xmin,xmax = T.bbox()
T= T.trl(-T.center()).scale(4./(xmax[0]-xmin[0])).setProp(2)
draw(T)
# default image file
filename = getcfg('datadir')+'/benedict_6.jpg'
viewer = ImageView(filename)
px,py = 5,5 #control points for projection of patches
kx,ky = 60,50 #number of cells in each patch
scale = 0.8
method='projection'
res = askItems([
I('filename',filename,text='Image file',itemtype='button',func=selectImage),
def run():
clear()
linewidth(2)
flatwire()
setDrawOptions({'bbox': 'auto'})
# A tapered grid of points
F = Formex([0.]).replic2(10, 5, taper=-1)
draw(F)
# Split in parts by testing y-position; note use of implicit loop!
G = [F.clip(F.test(dir=1, min=i - 0.5, max=i + 0.5)) for i in range(5)]
print([Gi.nelems() for Gi in G])
def annot(char):
[
drawText3D(G[i][0, 0] + [-0.5, 0., 0.], "%s%s" % (char, i))
for i, Gi in enumerate(G)
]
# Apply a general mapping function : x,y,x -> [ newx, newy, newz ]
G = [
Gi.map(lambda x, y, z: [x, y + 0.01 * float(i + 1)**1.5 * x**2, z])
for i, Gi in enumerate(G)
]
clear()
draw(G)
annot('G')
setDrawOptions({'bbox': 'last'})
# Connect G0 with G1
H1 = connect([G[0], G[1]])
draw(H1, color=blue)
# Connect G1 with G2 with a 2-element bias
H2 = connect([G[1], G[2]], bias=[0, 2])
draw(H2, color=green)
# Connect G3 with G4 with a 1-element bias plus loop
H2 = connect([G[3], G[4]], bias=[1, 0], loop=True)
draw(H2, color=red)
# Create a triangular grid of bars
clear()
draw(G)
annot('G')
# Connect Gi[j] with Gi[j+1] to create horizontals
K1 = [connect([i, i], bias=[0, 1]) for i in G]
draw(K1, color=blue)
# Connect Gi[j] with Gi+1[j] to create verticals
K2 = [connect([i, j]) for i, j in zip(G[:-1], G[1:])]
draw(K2, color=red)
# Connect Gi[j+1] with Gi+1[j] to create diagonals
K3 = [connect([i, j], bias=[1, 0]) for i, j in zip(G[:-1], G[1:])]
draw(K3, color=green)
# Create triangles
clear()
draw(G)
annot('G')
L1 = [connect([i, i, j], bias=[0, 1, 0]) for i, j in zip(G[:-1], G[1:])]
draw(L1, color=red)
L2 = [connect([i, j, j], bias=[1, 0, 1]) for i, j in zip(G[:-1], G[1:])]
draw(L2, color=green)
# Connecting multiplex Formices using bias
clear()
annot('K')
draw(K1)
L1 = [connect([i, i, j], bias=[0, 1, 0]) for i, j in zip(K1[:-1], K1[1:])]
draw(L1, color=red)
L2 = [connect([i, j, j], bias=[1, 0, 1]) for i, j in zip(K1[:-1], K1[1:])]
draw(L2, color=green)
# Connecting multiplex Formices using nodid
clear()
draw(K1)
annot('K')
L1 = [connect([i, i, j], nodid=[0, 1, 0]) for i, j in zip(K1[:-1], K1[1:])]
draw(L1, color=red)
L2 = [connect([i, j, j], nodid=[1, 0, 1]) for i, j in zip(K1[:-1], K1[1:])]
draw(L2, color=green)
# Add the missing end triangles
L3 = [
connect([i, i, j],
nodid=[0, 1, 1],
bias=[i.nelems() - 1,
i.nelems() - 1,
j.nelems() - 1]) for i, j in zip(K1[:-1], K1[1:])
]
draw(L3, color=magenta)
# Collect all triangles in a single Formex
L = (Formex.concatenate(L1) +
Formex.concatenate(L3)).setProp(1) + Formex.concatenate(L2).setProp(2)
clear()
draw(L)
# Convert to a Mesh
print("nelems = %s, nplex = %s, coords = %s" %
(L.nelems(), L.nplex(), L.coords.shape))
M = L.toMesh()
print("nelems = %s, nplex = %s, coords = %s" %
(M.nelems(), M.nplex(), M.coords.shape))
clear()
draw(M, color=yellow, mode='flatwire')
drawNumbers(M)
draw(M.getBorderMesh(), color=black, linewidth=6)
# Convert to a surface
from plugins.trisurface import TriSurface
S = TriSurface(M)
print("nelems = %s, nplex = %s, coords = %s" %
(S.nelems(), S.nplex(), S.coords.shape))
clear()
draw(S)
print("Total surface area: %s" % S.area())
export({'surface-1': S})
setDrawOptions({'bbox': 'auto'})
def createShellModel():
"""Create the Finite Element Model.
It is supposed here that the Geometry has been created and is available
as a global variable F.
"""
# Turn the Formex structure into a TriSurface
# This guarantees that element i of the Formex is element i of the TriSurface
S = TriSurface(F)
print "The structure has %s nodes, %s edges and %s faces" % (S.ncoords(),S.nedges(),S.nfaces())
nodes = S.coords
elems = S.elems # the triangles
clear()
draw(F)
# Shell section and material properties
# VALUES SHOULD BE SET CORRECTLY
glass_plate = {
'name': 'glass_plate',
'sectiontype': 'shell',
'thickness': 18,
'material': 'glass',
}
glass = {
'name': 'glass',
'young_modulus': 72000,
'shear_modulus': 26200,
'density': 2.5e-9, # T/mm**3
}
print glass_plate
print glass
glasssection = ElemSection(section=glass_plate,material=glass)
PDB = PropertyDB()
# All elements have same property:
PDB.elemProp(set=arange(len(elems)),section=glasssection,eltype='STRI3')
# Calculate the nodal loads
# Area of triangles
area,normals = S.areaNormals()
print "Area:\n%s" % area
### DEFINE LOAD CASE (ask user) ###
res = askItems([('Glass',True),('Snow',False)])
if not res:
return
step = 0
if res['Glass']:
step += 1
NODLoad = zeros((S.ncoords(),3))
# add the GLASS weight
wgt = 450e-6 # N/mm**2
# Or, calculate weight from density:
# wgt = glass_plate['thickness'] * glass['density'] * 9810
# assemble uniform glass load
for e,a in zip(S.elems,area):
NODLoad[e] += [ 0., 0., - a * wgt / 3 ]
# Put the nodal loads in the properties database
for i,P in enumerate(NODLoad):
PDB.nodeProp(tag=step,set=i,cload=[P[0],P[1],P[2],0.,0.,0.])
if res['Snow']:
step += 1
NODLoad = zeros((S.ncoords(),3))
# add NON UNIFORM SNOW
fn = 'hesperia-nieve.prop'
snowp = fromfile(fn,sep=',')
snow_uniform = 320e-6 # N/mm**2
snow_non_uniform = { 1:333e-6, 2:133e-6, 3:133e-6, 4:266e-6, 5:266e-6, 6:667e-6 }
# assemble non-uniform snow load
for e,a,p in zip(S.elems,area,snowp):
NODLoad[e] += [ 0., 0., - a * snow_non_uniform[p] / 3]
# Put the nodal loads in the properties database
for i,P in enumerate(NODLoad):
PDB.nodeProp(tag=step,set=[i],cload=[P[0],P[1],P[2],0.,0.,0.])
# Get support nodes
botnodes = where(isClose(nodes[:,2], 0.0))[0]
bot = nodes[botnodes].reshape((-1,1,3))
pf.message("There are %s support nodes." % bot.shape[0])
botofs = bot + [ 0.,0.,-0.2]
bbot2 = concatenate([bot,botofs],axis=1)
print bbot2.shape
S = Formex(bbot2)
draw(S)
## np_central_loaded = NodeProperty(3, displacement=[[1,radial_displacement]],coords='cylindrical',coordset=[0,0,0,0,0,1])
## #np_transf = NodeProperty(0,coords='cylindrical',coordset=[0,0,0,0,0,1])
## # Radial movement only
## np_fixed = NodeProperty(1,bound=[0,1,1,0,0,0],coords='cylindrical',coordset=[0,0,0,0,0,1])
# Since we left out the ring beam, we enforce no movement at the botnodes
bc = PDB.nodeProp(set=botnodes,bound=[1,1,1,0,0,0],csys=CoordSystem('C',[0,0,0,0,0,1]))
# And we record the name of the bottom nodes set
botnodeset = Nset(bc.nr)
fe_model = Dict(dict(nodes=nodes,elems=elems,prop=PDB,botnodeset=botnodeset,nsteps=step))
export({'fe_model':fe_model})
smooth()
lights(False)
def createFrameModel():
"""Create the Finite Element Model.
It is supposed here that the Geometry has been created and is available
as a global variable F.
"""
wireframe()
lights(False)
# Turn the Formex structure into a TriSurface
# This guarantees that element i of the Formex is element i of the TriSurface
S = TriSurface(F)
nodes = S.coords
elems = S.elems # the triangles
# Create edges and faces from edges
print "The structure has %s nodes, %s edges and %s faces" % (S.ncoords(),S.nedges(),S.nfaces())
# Create the steel structure
E = Formex(nodes[S.getEdges()])
clear()
draw(E)
# Get the tri elements that are part of a quadrilateral:
prop = F.prop
quadtri = S.getFaceEdges()[prop==6]
nquadtri = quadtri.shape[0]
print "%s triangles are part of quadrilateral faces" % nquadtri
if nquadtri > 0:
# Create triangle definitions of the quadtri faces
tri = Connectivity.tangle(quadtri,S.getEdges())
D = Formex(nodes[tri])
clear()
flatwire()
draw(D,color='yellow')
conn = connections(quadtri)
print conn
# Filter out the single connection edges
internal = [ c[0] for c in conn if len(c[1]) > 1 ]
print "Internal edges in quadrilaterals: %s" % internal
E = Formex(nodes[S.getEdges()],1)
E.prop[internal] = 6
wireframe()
clear()
draw(E)
# Remove internal edges
tubes = S.getEdges()[E.prop != 6]
print "Number of tube elements after removing %s internals: %s" % (len(internal),tubes.shape[0])
D = Formex(nodes[tubes],1)
clear()
draw(D)
# Beam section and material properties
b = 60
h = 100
t = 4
b1 = b-2*t
h1 = h-2*t
A = b*h - b1*h1
print b*h**3
I1 = (b*h**3 - b1*h1**3) / 12
I2 = (h*b**3 - h1*b1**3) / 12
I12 = 0
J = 4 * A**2 / (2*(b+h)/t)
tube = {
'name':'tube',
'cross_section': A,
'moment_inertia_11': I1,
'moment_inertia_22': I2,
'moment_inertia_12': I12,
'torsional_constant': J
}
steel = {
'name':'steel',
'young_modulus' : 206000,
'shear_modulus' : 81500,
'density' : 7.85e-9,
}
print tube
print steel
tubesection = ElemSection(section=tube,material=steel)
# Calculate the nodal loads
# Area of triangles
area,normals = S.areaNormals()
print "Area:\n%s" % area
# compute bar lengths
bars = nodes[tubes]
barV = bars[:,1,:] - bars[:,0,:]
barL = sqrt((barV*barV).sum(axis=-1))
print "Member length:\n%s" % barL
### DEFINE LOAD CASE (ask user) ###
res = askItems([('Steel',True),
('Glass',True),
('Snow',False),
('Solver',None,'select',['Calpy','Abaqus']),
])
if not res:
return
nlc = 0
for lc in [ 'Steel','Glass','Snow' ]:
if res[lc]:
nlc += 1
NODLoad = zeros((nlc,S.ncoords(),3))
nlc = 0
if res['Steel']:
# the STEEL weight
lwgt = steel['density'] * tube['cross_section'] * 9810 # mm/s**2
print "Weight per length %s" % lwgt
# assemble steel weight load
for e,L in zip(tubes,barL):
NODLoad[nlc,e] += [ 0., 0., - L * lwgt / 2 ]
nlc += 1
if res['Glass']:
# the GLASS weight
wgt = 450e-6 # N/mm**2
# assemble uniform glass load
for e,a in zip(S.elems,area):
NODLoad[nlc,e] += [ 0., 0., - a * wgt / 3 ]
nlc += 1
if res['Snow']:
# NON UNIFORM SNOW
fn = 'hesperia-nieve.prop'
snowp = fromfile(fn,sep=',')
snow_uniform = 320e-6 # N/mm**2
snow_non_uniform = { 1:333e-6, 2:133e-6, 3:133e-6, 4:266e-6, 5:266e-6, 6:667e-6 }
# assemble non-uniform snow load
for e,a,p in zip(S.elems,area,snowp):
NODLoad[nlc,e] += [ 0., 0., - a * snow_non_uniform[p] / 3]
nlc += 1
# For Abaqus: put the nodal loads in the properties database
print NODLoad
PDB = PropertyDB()
for lc in range(nlc):
for i,P in enumerate(NODLoad[lc]):
PDB.nodeProp(tag=lc,set=i,cload=[P[0],P[1],P[2],0.,0.,0.])
# Get support nodes
botnodes = where(isClose(nodes[:,2], 0.0))[0]
bot = nodes[botnodes]
pf.message("There are %s support nodes." % bot.shape[0])
# Upper structure
nnodes = nodes.shape[0] # node number offset
ntubes = tubes.shape[0] # element number offset
PDB.elemProp(set=arange(ntubes),section=tubesection,eltype='FRAME3D')
# Create support systems (vertical beams)
bot2 = bot + [ 0.,0.,-200.] # new nodes 200mm below bot
botnodes2 = arange(botnodes.shape[0]) + nnodes # node numbers
nodes = concatenate([nodes,bot2])
supports = column_stack([botnodes,botnodes2])
elems = concatenate([tubes,supports])
## !!!
## THIS SHOULD BE FIXED !!!
supportsection = ElemSection(material=steel,section={
'name':'support',
'cross_section': A,
'moment_inertia_11': I1,
'moment_inertia_22': I2,
'moment_inertia_12': I12,
'torsional_constant': J
})
PDB.elemProp(set=arange(ntubes,elems.shape[0]),section=supportsection,eltype='FRAME3D')
# Finally, the botnodes2 get the support conditions
botnodes = botnodes2
## # Radial movement only
## np_fixed = NodeProperty(1,bound=[0,1,1,0,0,0],coords='cylindrical',coordset=[0,0,0,0,0,1])
## # No movement, since we left out the ring beam
## for i in botnodes:
## NodeProperty(i,bound=[1,1,1,0,0,0],coords='cylindrical',coordset=[0,0,0,0,0,1])
## np_central_loaded = NodeProperty(3, displacement=[[1,radial_displacement]],coords='cylindrical',coordset=[0,0,0,0,0,1])
## #np_transf = NodeProperty(0,coords='cylindrical',coordset=[0,0,0,0,0,1])
# Draw the supports
S = connect([Formex(bot),Formex(bot2)])
draw(S,color='black')
if res['Solver'] == 'Calpy':
fe_model = Dict(dict(solver='Calpy',nodes=nodes,elems=elems,prop=PDB,loads=NODLoad,botnodes=botnodes,nsteps=nlc))
else:
fe_model = Dict(dict(solver='Abaqus',nodes=nodes,elems=elems,prop=PDB,botnodes=botnodes,nsteps=nlc))
export({'fe_model':fe_model})
print "FE model created and exported as 'fe_model'"
# Add the missing end triangles
L3 = [ connect([i,i,j],nodid=[0,1,1],bias=[i.nelems()-1,i.nelems()-1,j.nelems()-1]) for i,j in zip(K1[:-1],K1[1:]) ]
draw(L3,color=magenta)
# Collect all triangles in a single Formex
L = (Formex.concatenate(L1)+Formex.concatenate(L3)).setProp(1) + Formex.concatenate(L2).setProp(2)
clear()
draw(L)
# Convert to a Mesh
print "nelems = %s, nplex = %s, coords = %s" % (L.nelems(),L.nplex(),L.coords.shape)
M = L.toMesh()
print "nelems = %s, nplex = %s, coords = %s" % (M.nelems(),M.nplex(),M.coords.shape)
clear()
draw(M,color=yellow,mode=flatwire)
drawNumbers(M)
draw(M.getBorderMesh(),color=black,linewidth=6)
# Convert to a surface
from plugins.trisurface import TriSurface
S = TriSurface(M)
print "nelems = %s, nplex = %s, coords = %s" % (S.nelems(),S.nplex(),S.coords.shape)
clear()
draw(S)
print "Total surface area: %s" % S.area()
export({'surface-1':S})
setDrawOptions({'bbox':'auto'})
# End
def createFrameModel():
"""Create the Finite Element Model.
It is supposed here that the Geometry has been created and is available
as a global variable F.
"""
wireframe()
lights(False)
# Turn the Formex structure into a TriSurface
# This guarantees that element i of the Formex is element i of the TriSurface
S = TriSurface(F)
nodes = S.coords
elems = S.elems # the triangles
# Create edges and faces from edges
print("The structure has %s nodes, %s edges and %s faces" %
(S.ncoords(), S.nedges(), S.nfaces()))
# Remove the edges between to quad triangles
drawNumbers(S.coords)
quadtri = where(S.prop == 6)[0]
nquadtri = quadtri.shape[0]
print("%s triangles are part of quadrilateral faces" % nquadtri)
faces = S.getElemEdges()[quadtri]
cnt, ind, xbin = histogram2(faces.reshape(-1), arange(faces.max() + 1))
rem = where(cnt == 2)[0]
print("Total edges %s" % len(S.edges))
print("Removing %s edges" % len(rem))
edges = S.edges[complement(rem, n=len(S.edges))]
print("Remaining edges %s" % len(edges))
# Create the steel structure
E = Formex(nodes[edges])
clear()
draw(E)
warning("Beware! This script is currently under revision.")
conn = connections(quadtri)
print(conn)
# Filter out the single connection edges
internal = [c[0] for c in conn if len(c[1]) > 1]
print("Internal edges in quadrilaterals: %s" % internal)
E = Formex(nodes[edges], 1)
E.prop[internal] = 6
wireframe()
clear()
draw(E)
# Remove internal edges
tubes = edges[E.prop != 6]
print("Number of tube elements after removing %s internals: %s" %
(len(internal), tubes.shape[0]))
D = Formex(nodes[tubes], 1)
clear()
draw(D)
# Beam section and material properties
b = 60
h = 100
t = 4
b1 = b - 2 * t
h1 = h - 2 * t
A = b * h - b1 * h1
print(b * h**3)
I1 = (b * h**3 - b1 * h1**3) / 12
I2 = (h * b**3 - h1 * b1**3) / 12
I12 = 0
J = 4 * A**2 / (2 * (b + h) / t)
tube = {
'name': 'tube',
'cross_section': A,
'moment_inertia_11': I1,
'moment_inertia_22': I2,
'moment_inertia_12': I12,
'torsional_constant': J
}
steel = {
'name': 'steel',
'young_modulus': 206000,
'shear_modulus': 81500,
'density': 7.85e-9,
}
print(tube)
print(steel)
tubesection = ElemSection(section=tube, material=steel)
# Calculate the nodal loads
# Area of triangles
area, normals = S.areaNormals()
print("Area:\n%s" % area)
# compute bar lengths
bars = nodes[tubes]
barV = bars[:, 1, :] - bars[:, 0, :]
barL = sqrt((barV * barV).sum(axis=-1))
print("Member length:\n%s" % barL)
### DEFINE LOAD CASE (ask user) ###
res = askItems([
_I('Steel', True),
_I('Glass', True),
_I('Snow', False),
_I('Solver', choices=['Calpy', 'Abaqus']),
])
if not res:
return
nlc = 0
for lc in ['Steel', 'Glass', 'Snow']:
if res[lc]:
nlc += 1
NODLoad = zeros((nlc, S.ncoords(), 3))
nlc = 0
if res['Steel']:
# the STEEL weight
lwgt = steel['density'] * tube['cross_section'] * 9810 # mm/s**2
print("Weight per length %s" % lwgt)
# assemble steel weight load
for e, L in zip(tubes, barL):
NODLoad[nlc, e] += [0., 0., -L * lwgt / 2]
nlc += 1
if res['Glass']:
# the GLASS weight
wgt = 450e-6 # N/mm**2
# assemble uniform glass load
for e, a in zip(S.elems, area):
NODLoad[nlc, e] += [0., 0., -a * wgt / 3]
nlc += 1
if res['Snow']:
# NON UNIFORM SNOW
fn = '../data/hesperia-nieve.prop'
snowp = fromfile(fn, sep=',')
snow_uniform = 320e-6 # N/mm**2
snow_non_uniform = {
1: 333e-6,
2: 133e-6,
3: 133e-6,
4: 266e-6,
5: 266e-6,
6: 667e-6
}
# assemble non-uniform snow load
for e, a, p in zip(S.elems, area, snowp):
NODLoad[nlc, e] += [0., 0., -a * snow_non_uniform[p] / 3]
nlc += 1
# For Abaqus: put the nodal loads in the properties database
print(NODLoad)
PDB = PropertyDB()
for lc in range(nlc):
for i, P in enumerate(NODLoad[lc]):
PDB.nodeProp(tag=lc, set=i, cload=[P[0], P[1], P[2], 0., 0., 0.])
# Get support nodes
botnodes = where(isClose(nodes[:, 2], 0.0))[0]
bot = nodes[botnodes]
pf.message("There are %s support nodes." % bot.shape[0])
# Upper structure
nnodes = nodes.shape[0] # node number offset
ntubes = tubes.shape[0] # element number offset
PDB.elemProp(set=arange(ntubes), section=tubesection, eltype='FRAME3D')
# Create support systems (vertical beams)
bot2 = bot + [0., 0., -200.] # new nodes 200mm below bot
botnodes2 = arange(botnodes.shape[0]) + nnodes # node numbers
nodes = concatenate([nodes, bot2])
supports = column_stack([botnodes, botnodes2])
elems = concatenate([tubes, supports])
## !!!
## THIS SHOULD BE FIXED !!!
supportsection = ElemSection(material=steel,
section={
'name': 'support',
'cross_section': A,
'moment_inertia_11': I1,
'moment_inertia_22': I2,
'moment_inertia_12': I12,
'torsional_constant': J
})
PDB.elemProp(set=arange(ntubes, elems.shape[0]),
section=supportsection,
eltype='FRAME3D')
# Finally, the botnodes2 get the support conditions
botnodes = botnodes2
## # Radial movement only
## np_fixed = NodeProperty(1,bound=[0,1,1,0,0,0],coords='cylindrical',coordset=[0,0,0,0,0,1])
## # No movement, since we left out the ring beam
## for i in botnodes:
## NodeProperty(i,bound=[1,1,1,0,0,0],coords='cylindrical',coordset=[0,0,0,0,0,1])
## np_central_loaded = NodeProperty(3, displacement=[[1,radial_displacement]],coords='cylindrical',coordset=[0,0,0,0,0,1])
## #np_transf = NodeProperty(0,coords='cylindrical',coordset=[0,0,0,0,0,1])
# Draw the supports
S = connect([Formex(bot), Formex(bot2)])
draw(S, color='black')
if res['Solver'] == 'Calpy':
fe_model = Dict(
dict(solver='Calpy',
nodes=nodes,
elems=elems,
prop=PDB,
loads=NODLoad,
botnodes=botnodes,
nsteps=nlc))
else:
fe_model = Dict(
dict(solver='Abaqus',
nodes=nodes,
elems=elems,
prop=PDB,
botnodes=botnodes,
nsteps=nlc))
export({'fe_model': fe_model})
print("FE model created and exported as 'fe_model'")
def createShellModel():
"""Create the Finite Element Model.
It is supposed here that the Geometry has been created and is available
as a global variable F.
"""
# Turn the Formex structure into a TriSurface
# This guarantees that element i of the Formex is element i of the TriSurface
S = TriSurface(F)
print("The structure has %s nodes, %s edges and %s faces" %
(S.ncoords(), S.nedges(), S.nfaces()))
nodes = S.coords
elems = S.elems # the triangles
clear()
draw(F)
# Shell section and material properties
# VALUES SHOULD BE SET CORRECTLY
glass_plate = {
'name': 'glass_plate',
'sectiontype': 'shell',
'thickness': 18,
'material': 'glass',
}
glass = {
'name': 'glass',
'young_modulus': 72000,
'shear_modulus': 26200,
'density': 2.5e-9, # T/mm**3
}
print(glass_plate)
print(glass)
glasssection = ElemSection(section=glass_plate, material=glass)
PDB = PropertyDB()
# All elements have same property:
PDB.elemProp(set=arange(len(elems)), section=glasssection, eltype='STRI3')
# Calculate the nodal loads
# Area of triangles
area, normals = S.areaNormals()
print("Area:\n%s" % area)
### DEFINE LOAD CASE (ask user) ###
res = askItems([('Glass', True), ('Snow', False)])
if not res:
return
step = 0
if res['Glass']:
step += 1
NODLoad = zeros((S.ncoords(), 3))
# add the GLASS weight
wgt = 450e-6 # N/mm**2
# Or, calculate weight from density:
# wgt = glass_plate['thickness'] * glass['density'] * 9810
# assemble uniform glass load
for e, a in zip(S.elems, area):
NODLoad[e] += [0., 0., -a * wgt / 3]
# Put the nodal loads in the properties database
for i, P in enumerate(NODLoad):
PDB.nodeProp(tag=step, set=i, cload=[P[0], P[1], P[2], 0., 0., 0.])
if res['Snow']:
step += 1
NODLoad = zeros((S.ncoords(), 3))
# add NON UNIFORM SNOW
fn = '../data/hesperia-nieve.prop'
snowp = fromfile(fn, sep=',')
snow_uniform = 320e-6 # N/mm**2
snow_non_uniform = {
1: 333e-6,
2: 133e-6,
3: 133e-6,
4: 266e-6,
5: 266e-6,
6: 667e-6
}
# assemble non-uniform snow load
for e, a, p in zip(S.elems, area, snowp):
NODLoad[e] += [0., 0., -a * snow_non_uniform[p] / 3]
# Put the nodal loads in the properties database
for i, P in enumerate(NODLoad):
PDB.nodeProp(tag=step,
set=[i],
cload=[P[0], P[1], P[2], 0., 0., 0.])
# Get support nodes
botnodes = where(isClose(nodes[:, 2], 0.0))[0]
bot = nodes[botnodes].reshape((-1, 1, 3))
pf.message("There are %s support nodes." % bot.shape[0])
botofs = bot + [0., 0., -0.2]
bbot2 = concatenate([bot, botofs], axis=1)
print(bbot2.shape)
S = Formex(bbot2)
draw(S)
## np_central_loaded = NodeProperty(3, displacement=[[1,radial_displacement]],coords='cylindrical',coordset=[0,0,0,0,0,1])
## #np_transf = NodeProperty(0,coords='cylindrical',coordset=[0,0,0,0,0,1])
## # Radial movement only
## np_fixed = NodeProperty(1,bound=[0,1,1,0,0,0],coords='cylindrical',coordset=[0,0,0,0,0,1])
# Since we left out the ring beam, we enforce no movement at the botnodes
bc = PDB.nodeProp(set=botnodes,
bound=[1, 1, 1, 0, 0, 0],
csys=CoordSystem('C', [0, 0, 0, 0, 0, 1]))
# And we record the name of the bottom nodes set
botnodeset = Nset(bc.nr)
fe_model = Dict(
dict(nodes=nodes,
elems=elems,
prop=PDB,
botnodeset=botnodeset,
nsteps=step))
export({'fe_model': fe_model})
smooth()
lights(False)
def run():
global wviewer,pcolor,px,py
clear()
smooth()
lights(True)
transparent(False)
view('iso')
image = None
scaled_image = None
# read the teapot surface
T = TriSurface.read(getcfg('datadir')+'/teapot.off')
xmin,xmax = T.bbox()
T= T.trl(-T.center()).scale(4./(xmax[0]-xmin[0])).setProp(2)
draw(T)
# default image file
dfilename = getcfg('datadir')+'/benedict_6.jpg'
wviewer = ImageView(dfilename,maxheight=200)
res = askItems([
_I('filename',dfilename,text='Image file',itemtype='button',func=selectImage),
wviewer,
_I('px',4,text='Number of patches in x-direction'),
_I('py',6,text='Number of patches in y-direction'),
_I('kx',30,text='Width of a patch in pixels'),
_I('ky',30,text='Height of a patch in pixels'),
_I('scale',1.0,text='Scale factor'),
_I('trl',[-0.4,-0.1,2.],itemtype='point',text='Translation'),
_I('method',choices=['projection','intersection']),
])
if not res:
return
globals().update(res)
nx,ny = px*kx,py*ky # pixels
print('The image is reconstructed with %d x %d pixels'%(nx, ny))
F = Formex('4:0123').replic2(nx,ny).centered()
if image is None:
print("Loading image")
image = loadImage(filename)
wpic,hpic = image.width(),image.height()
print("Image size is %sx%s" % (wpic,hpic))
if image is None:
return
# Create the colors
color,colortable = image2glcolor(image.scaled(nx,ny))
# Reorder by patch
pcolor = color.reshape((py,ky,px,kx,3)).swapaxes(1,2).reshape(-1,kx*ky,3)
print("Shape of the colors array: %s" % str(pcolor.shape))
mH = makeGrid(px,py,'Quad8')
try:
ratioYX = float(hpic)/wpic
mH = mH.scale(ratioYX,1) # Keep original aspect ratio
except:
pass
mH0 = mH.scale(scale).translate(trl)
dg0 = draw(mH0,mode='wireframe')
zoomAll()
zoom(0.5)
print("Create %s x %s patches" % (px,py))
# Create the transforms
base = makeGrid(1,1,'Quad8').coords[0]
patch = makeGrid(kx,ky,'Quad4').toMesh()
d0 = drawImage(mH0,base,patch)
if method == 'projection':
pts = mH0.coords.projectOnSurface(T,[0.,0.,1.],'-f')
dg1 = d1 = [] # to allow dummy undraw
else:
mH1 = mH.rotate(-30.,0).scale(0.5).translate([0.,-.7,-2.])
dg1 = draw(mH1,mode='wireframe')
d1 = drawImage(mH1,base,patch)
x = connect([mH0.asPoints(),mH1.asPoints()])
dx = draw(x)
print("Creating intersection with surface")
pts, il, it, mil=intersectSurfaceWithSegments2(T, x, max1xperline=True)
if len(x) != len(pts):
print("Some of the lines do not intersect the surface:")
print(" %d lines, %d intersections %d missing" % (len(x),len(pts),len(mil)))
return
dp = draw(pts, marksize=6, color='white')
#print pts.shape
mH2 = Formex(pts.reshape(-1,8,3))
if method == 'projection':
x = connect([mH0.points(),mH2.points()])
dx = draw(x)
print("Create projection mapping using the grid points")
d2 = drawImage(mH2.trl([0.,0.,0.01]),base,patch)
# small translation to make sure the image is above the surface, not cutting it
print("Finally show the finished image")
undraw(dp);
undraw(dx);
undraw(d0);
undraw(d1);
undraw(dg0);
undraw(dg1);
view('front')
zoomAll()
sleep(1)
transparent()
##
"""HorseTorse
level = 'advanced'
topics = ['geometry','surface','mesh']
techniques = ['intersection']
"""
from plugins.trisurface import TriSurface
from mesh import Mesh
reset()
smooth()
lights(True)
S = TriSurface.read(getcfg("datadir") + "/horse.off")
SA = draw(S)
res = askItems([("direction", [1.0, 0.0, 0.0]), ("number of sections", 20), ("color", "red"), ("ontop", False)])
if not res:
exit()
d = res["direction"]
n = res["number of sections"]
c = res["color"]
slices = S.slice(dir=d, nplanes=n)
linewidth(2)
draw(slices, color=c, view=None, bbox="last", nolight=True, ontop=res["ontop"])
draw(slices[0])
