def _arc_to_nurbs(self, t_min, t_max, implementation=SvNurbsMaths.NATIVE):
alpha = t_max - t_min
p0_x = cos(t_min)
p0_y = sin(t_min)
p2_x = cos(t_max)
p2_y = sin(t_max)
t_mid = 0.5 * (t_max + t_min)
theta = 0.5 * alpha
p1_r = 1.0 / cos(theta)
p1_x = p1_r * cos(t_mid)
p1_y = p1_r * sin(t_mid)
control_points = np.array([[p0_x, p0_y, 0], [p1_x, p1_y, 0],
[p2_x, p2_y, 0]])
control_points = self.radius * control_points
control_points = np.apply_along_axis(lambda v: self.matrix @ v, 1,
control_points)
control_points = self.center + control_points
w1 = cos(theta)
weights = np.array([1, w1, 1])
degree = 2
knotvector = sv_knotvector.generate(degree, 3)
knotvector = sv_knotvector.rescale(knotvector, t_min, t_max)
nurbs = SvNurbsMaths.build_curve(implementation, degree, knotvector,
control_points, weights)
if alpha > 2 * pi / 3:
nurbs = nurbs.insert_knot(t_mid)
return nurbs
def reparametrize(self, new_t_min, new_t_max):
kv = self.get_knotvector()
t_min, t_max = kv[0], kv[-1]
if t_min == new_t_min and t_max == new_t_max:
return self
knotvector = sv_knotvector.rescale(kv, new_t_min, new_t_max)
return SvNurbsCurve.build(self.get_nurbs_implementation(),
self.get_degree(), knotvector,
self.get_control_points(),
self.get_weights())
def to_nurbs(self, implementation=SvNurbsMaths.NATIVE):
u_min, u_max = self.get_u_bounds()
knotvector = sv_knotvector.generate(1, 2)
knotvector = sv_knotvector.rescale(knotvector, u_min, u_max)
p1 = self.evaluate(u_min)
p2 = self.evaluate(u_max)
control_points = np.array([p1, p2])
return SvNurbsMaths.build_curve(implementation,
degree=1,
knotvector=knotvector,
control_points=control_points)
def reparametrize(self, new_t_min, new_t_max):
knotvector = sv_knotvector.rescale(self.get_knotvector(), new_t_min, new_t_max)
return SvNurbsCurve.build(self.get_nurbs_implementation(),
self.get_degree(), knotvector, self.get_control_points(), self.get_weights())