def discretize_edge(a_topods_edge, deflection=0.5):
""" Take a TopoDS_Edge and returns a list of points
The more deflection is small, the more the discretization is precise,
i.e. the more points you get in the returned points
"""
if not is_edge(a_topods_edge):
raise AssertionError(
"You must provide a TopoDS_Edge to the discretize_edge function.")
if a_topods_edge.IsNull():
print(
"Warning : TopoDS_Edge is null. discretize_edge will return an empty list of points."
)
return []
curve_adaptator = BRepAdaptor_Curve(a_topods_edge)
first = curve_adaptator.FirstParameter()
last = curve_adaptator.LastParameter()
discretizer = GCPnts_UniformAbscissa()
discretizer.Initialize(curve_adaptator, deflection, first, last)
if not discretizer.IsDone():
raise AssertionError("Discretizer not done.")
if not discretizer.NbPoints() > 0:
raise AssertionError("Discretizer nb points not > 0.")
points = []
for i in range(1, discretizer.NbPoints() + 1):
p = curve_adaptator.Value(discretizer.Parameter(i))
points.append(p.Coord())
return points
def divide_by_number_of_points(self, n_pts, lbound=None, ubound=None):
'''returns a nested list of parameters and points on the edge
at the requested interval [(param, gp_Pnt),...]
'''
_lbound, _ubound = self.domain()
if lbound:
_lbound = lbound
elif ubound:
_ubound = ubound
# minimally two points or a Standard_ConstructionError is raised
if n_pts <= 1:
n_pts = 2
try:
npts = GCPnts_UniformAbscissa(self.adaptor, n_pts, _lbound, _ubound)
except:
print("Warning : GCPnts_UniformAbscissa failed")
if npts.IsDone():
tmp = []
for i in xrange(1, npts.NbPoints()+1):
param = npts.Parameter(i)
pnt = self.adaptor.Value(param)
tmp.append((param, pnt))
return tmp
else:
return None
def test_point_from_curve(self):
'''Test: point from curve'''
radius, abscissa = 5., 3.
C = Geom2d_Circle(gp_OX2d(), radius, True)
GAC = Geom2dAdaptor_Curve(C)
UA = GCPnts_UniformAbscissa(GAC, abscissa)
aSequence = []
if UA.IsDone():
N = UA.NbPoints()
for count in range(1, N + 1):
P = gp_Pnt2d()
C.D0(UA.Parameter(count), P)
Parameter = UA.Parameter(count)
self.assertIsInstance(Parameter, float)
aSequence.append(P)
Abscissa = UA.Abscissa()
self.assertEqual(Abscissa, abscissa)
def divide_edge_by_nr_of_points(edg, n_pts):
'''returns a nested list of parameters and points on the edge
at the requested interval [(param, gp_Pnt),...]
'''
curve_adapt = BRepAdaptor_Curve(edg)
_lbound, _ubound = curve_adapt.FirstParameter(), curve_adapt.LastParameter(
)
if n_pts <= 1:
# minimally two points or a Standard_ConstructionError is raised
raise AssertionError("minimally 2 points required")
npts = GCPnts_UniformAbscissa(curve_adapt, n_pts, _lbound, _ubound)
if npts.IsDone():
tmp = []
for i in range(1, npts.NbPoints() + 1):
param = npts.Parameter(i)
pnt = curve_adapt.Value(param)
tmp.append((param, pnt))
return tmp
def points_from_curve():
radius = 5.
abscissa = 3.
circle = Geom2d_Circle(gp_OX2d(), radius, True)
gac = Geom2dAdaptor_Curve(circle)
ua = GCPnts_UniformAbscissa(gac, abscissa)
a_sequence = []
if ua.IsDone():
n = ua.NbPoints()
for count in range(1, n + 1):
p = gp_Pnt2d()
circle.D0(ua.Parameter(count), p)
a_sequence.append(p)
# convert analytic to bspline
display.DisplayShape(circle, update=True)
i = 0
for p in a_sequence:
i = i + 1
pstring = 'P%i : parameter %f' % (i, ua.Parameter(i))
pnt = gp_Pnt(p.X(), p.Y(), 0)
# display points
display.DisplayShape(pnt, update=True)
display.DisplayMessage(pnt, pstring)