def CircularArcFromNormal(center, resolution=100, normal=None,
polar=None, angle=None):
"""Create a circular arc defined by normal to the plane of the arc, and an angle.
The number of segments composing the polyline is controlled by
setting the object resolution.
Parameters
----------
center : np.ndarray or list
Center of the circle that defines the arc.
resolution : int, optional
The number of segments of the polyline that draws the arc.
Resolution of 1 will just create a line.
normal : np.ndarray or list, optional
The normal vector to the plane of the arc. By default it
points in the positive Z direction.
polar : np.ndarray or list, optional
Starting point of the arc in polar coordinates. By default it
is the unit vector in the positive x direction.
angle : float, optional
Arc length (in degrees) beginning at the polar vector. The
direction is counterclockwise. By default it is 360.
Examples
--------
Quarter arc centered at the origin in the xy plane.
>>> import pyvista
>>> normal = [0, 0, 1]
>>> polar = [-1, 0, 0]
>>> arc = pyvista.CircularArcFromNormal([0, 0, 0], normal=normal, polar=polar)
>>> pl = pyvista.Plotter()
>>> _ = pl.add_mesh(arc, color='k', line_width=4)
>>> _ = pl.show_bounds(location='all')
>>> _ = pl.view_xy()
>>> pl.show() # doctest:+SKIP
"""
check_valid_vector(center, 'center')
if normal is None:
normal = [0, 0, 1]
if polar is None:
polar = [1, 0, 0]
if angle is None:
angle = 90.0
arc = _vtk.vtkArcSource()
arc.SetCenter(*center)
arc.SetResolution(resolution)
arc.UseNormalAndAngleOn()
check_valid_vector(normal, 'normal')
arc.SetNormal(*normal)
check_valid_vector(polar, 'polar')
arc.SetPolarVector(*polar)
assert np.allclose(np.array(arc.GetPolarVector()), np.array(polar))
arc.SetAngle(angle)
arc.Update()
angle = np.deg2rad(arc.GetAngle())
arc = pyvista.wrap(arc.GetOutput())
# Compute distance of every point along circular arc
center = np.array(center)
radius = np.sqrt(np.sum((arc.points[0] - center)**2, axis=0))
angles = np.arange(0.0, 1.0 + 1.0/resolution, 1.0/resolution) * angle
arc['Distance'] = radius * angles
return arc
def CircularArc(pointa, pointb, center, resolution=100, normal=None,
polar=None, angle=None, negative=False):
"""Create a circular arc defined by two endpoints and a center.
The number of segments composing the polyline is controlled by
setting the object resolution. Alternatively, one can use a
better API (that does not allow for inconsistent nor ambiguous
inputs), using a starting point (polar vector, measured from the
arc's center), a normal to the plane of the arc, and an angle
defining the arc length.
Parameters
----------
pointa : np.ndarray or list
Position of the first end point.
pointb : np.ndarray or list
Position of the other end point.
center : np.ndarray or list
Center of the circle that defines the arc.
resolution : int, optional
The number of segments of the polyline that draws the arc.
Resolution of 1 will just create a line.
normal : np.ndarray or list
The normal vector to the plane of the arc. By default it
points in the positive Z direction.
polar : np.ndarray or list
(starting point of the arc). By default it is the unit vector
in the positive x direction. Note: This is only used when
normal has been input.
angle : float
Arc length (in degrees), beginning at the polar vector. The
direction is counterclockwise by default; a negative value
draws the arc in the clockwise direction. Note: This is only
used when normal has been input.
negative : bool, optional
By default the arc spans the shortest angular sector point1 and point2.
By setting this to true, the longest angular sector is used
instead (i.e. the negative coterminal angle to the shortest
one). This is only used when normal has not been input
Examples
--------
Quarter arc centered at the origin in the xy plane
>>> import pyvista
>>> arc = pyvista.CircularArc([-1, 0, 0], [0, 1, 0], [0, 0, 0])
>>> pl = pyvista.Plotter()
>>> _ = pl.add_mesh(arc, color='k', line_width=4)
>>> _ = pl.show_bounds(location='all')
>>> _ = pl.view_xy()
>>> pl.show() # doctest:+SKIP
Quarter arc centered at the origin in the xz plane
>>> arc = pyvista.CircularArc([-1, 0, 0], [1, 0, 0], [0, 0, 0], normal=[0, 0, 1])
>>> arc.plot() # doctest:+SKIP
"""
check_valid_vector(pointa, 'pointa')
check_valid_vector(pointb, 'pointb')
check_valid_vector(center, 'center')
# fix half-arc bug: if a half arc travels directly through the
# center point, it becomes a line
pointb = list(pointb)
pointb[0] -= 1E-10
pointb[1] -= 1E-10
arc = _vtk.vtkArcSource()
arc.SetPoint1(*pointa)
arc.SetPoint2(*pointb)
arc.SetCenter(*center)
arc.SetResolution(resolution)
arc.SetNegative(negative)
if normal is not None:
arc.UseNormalAndAngleOn()
check_valid_vector(normal, 'normal')
arc.SetNormal(*normal)
if polar is not None:
check_valid_vector(polar, 'polar')
arc.SetPolarVector(*polar)
if angle is not None:
arc.SetAngle(angle)
arc.Update()
return pyvista.wrap(arc.GetOutput())
def CircularArc(pointa, pointb, center, resolution=100, negative=False):
"""Create a circular arc defined by two endpoints and a center.
The number of segments composing the polyline is controlled by
setting the object resolution.
Parameters
----------
pointa : np.ndarray or list
Position of the first end point.
pointb : np.ndarray or list
Position of the other end point.
center : np.ndarray or list
Center of the circle that defines the arc.
resolution : int, optional
The number of segments of the polyline that draws the arc.
Resolution of 1 will just create a line.
negative : bool, optional
By default the arc spans the shortest angular sector between
``pointa`` and ``pointb``.
By setting this to ``True``, the longest angular sector is
used instead (i.e. the negative coterminal angle to the
shortest one).
Examples
--------
Create a quarter arc centered at the origin in the xy plane.
>>> import pyvista
>>> arc = pyvista.CircularArc([-1, 0, 0], [0, 1, 0], [0, 0, 0])
>>> pl = pyvista.Plotter()
>>> _ = pl.add_mesh(arc, color='k', line_width=4)
>>> _ = pl.show_bounds(location='all')
>>> _ = pl.view_xy()
>>> pl.show() # doctest:+SKIP
"""
check_valid_vector(pointa, 'pointa')
check_valid_vector(pointb, 'pointb')
check_valid_vector(center, 'center')
if not np.isclose(
np.linalg.norm(np.array(pointa) - np.array(center)),
np.linalg.norm(np.array(pointb) - np.array(center)),
):
raise ValueError("pointa and pointb are not equidistant from center")
# fix half-arc bug: if a half arc travels directly through the
# center point, it becomes a line
pointb = list(pointb)
pointb[0] -= 1E-10
pointb[1] -= 1E-10
arc = _vtk.vtkArcSource()
arc.SetPoint1(*pointa)
arc.SetPoint2(*pointb)
arc.SetCenter(*center)
arc.SetResolution(resolution)
arc.SetNegative(negative)
arc.Update()
angle = np.deg2rad(arc.GetAngle())
arc = pyvista.wrap(arc.GetOutput())
# Compute distance of every point along circular arc
center = np.array(center)
radius = np.sqrt(np.sum((arc.points[0]-center)**2, axis=0))
angles = np.arange(0.0, 1.0 + 1.0/resolution, 1.0/resolution) * angle
arc['Distance'] = radius * angles
return arc
