def tangentAt(self, locationVector=None):
"""
Compute tangent vector at the specified location.
:param locationVector: location to use. Use the center point if None
:return: tangent vector
"""
curve = self._geomAdaptor()
if locationVector:
raise NotImplementedError
else:
umin, umax = curve.FirstParameter(), curve.LastParameter()
umid = 0.5 * (umin + umax)
# TODO what are good parameters for those?
curve_props = BRepLProp_CLProps(curve, 2, curve.Tolerance())
curve_props.SetParameter(umid)
if curve_props.IsTangentDefined():
dir_handle = gp_Dir(
) # this is awkward due to C++ pass by ref in the API
curve_props.Tangent(dir_handle)
return Vector(dir_handle)
class DiffGeomCurve(object):
def __init__(self, instance):
self.instance = instance
from OCC.BRepLProp import BRepLProp_CLProps
# initialize with random parameter: 0
self._curvature = BRepLProp_CLProps(self.instance.adaptor, 0, 2, self.instance.tolerance)
def curvature(self, u, n, resolution=1e-7):
self._curvature.SetParameter(u)
def radius(self, u):
'''returns the radius at u
'''
# NOT SO SURE IF THIS IS THE SAME THING!!!
self._curvature.SetParameter(u)
pnt = gp_Pnt()
self._curvature.CentreOfCurvature(pnt)
return pnt
def curvature(self, u):
# TODO: find a better way to achieve this method
self._curvature.SetParameter(u)
return self._curvature.Curvature()
def tangent(self, u ):
'''sets or gets ( iff vector ) the tangency at the u parameter
tangency can be constrained so when setting the tangency, you're constrainting it in fact
'''
self._curvature.SetParameter(u)
if self._curvature.IsTangentDefined():
direction = gp_Dir()
self._curvature.Tangent(direction)
return ddd
else:
raise ValueError('no tangent defined')
def normal(self, u):
'''returns the normal at u
'''
try:
self._curvature.SetParameter(u)
ddd = gp_Dir()
self._curvature.Normal(ddd)
return ddd
except:
raise ValueError('no normal was found')
def derivative(self, u, n):
'''
returns n derivatives at parameter b
'''
self._curvature.SetParameter(u)
deriv = {1:self._curvature.D1,
2:self._curvature.D2,
3:self._curvature.D3,
}
try:
return deriv[n]
except KeyError:
raise AssertionError, 'n of derivative is one of [1,2,3]'
def points_from_tangential_deflection(self):
from OCC.GCPnts import GCPnts_TangentialDeflection
pass