def const_par_curve(self, knot, direction):
""" Get a Curve representation of the parametric line of some constant
knot value.
:param float knot: The constant knot value to sample the surface
:param int direction: The parametric direction for the constant value
:return: curve on this surface
:rtype: Curve
"""
direction = check_direction(direction, 2)
# clone basis since we need to augment this by knot insertion
b = self.bases[direction].clone()
# compute mapping matrix C which is the knotinsertion operator
mult = min(b.continuity(knot), b.order - 1)
C = np.identity(self.shape[direction])
for i in range(mult):
C = b.insert_knot(knot) @ C
# at this point we have a C0 basis, find the right interpolating index
i = max(bisect_left(b.knots, knot) - 1, 0)
# compute the controlpoints and return Curve
cp = np.tensordot(C[i, :], self.controlpoints, axes=(0, direction))
return Curve(self.bases[1 - direction], cp, self.rational)
def const_par_curve(self, knot, direction):
""" Get a Curve representation of the parametric line of some constant
knot value.
:param float knot: The constant knot value to sample the surface
:param int direction: The parametric direction for the constant value
:return: curve on this surface
:rtype: Curve
"""
direction = check_direction(direction, 2)
# clone basis since we need to augment this by knot insertion
b = self.bases[direction].clone()
# compute mapping matrix C which is the knotinsertion operator
mult = min(b.continuity(knot), b.order-1)
C = np.matrix(np.identity(self.shape[direction]))
for i in range(mult):
C = b.insert_knot(knot) * C
# at this point we have a C0 basis, find the right interpolating index
i = max(bisect_left(b.knots, knot) - 1,0)
# compute the controlpoints and return Curve
cp = np.tensordot(C[i,:], self.controlpoints, axes=(1, direction))
return Curve(self.bases[1-direction], cp, self.rational)
def geometric_refine(obj, alpha, n, direction=0, reverse=False):
"""geometric_refine(obj, alpha, n, [direction=0], [reverse=False])
Refine a spline object by making a geometric distribution of element sizes.
:param obj: The object to refine
:type obj: :class:`splipy.SplineObject`
:param float alpha: The length ratio between two sequential knot segments
:param int n: The number of knots to insert
:param direction: The direction to refine in
:param bool reverse: Set to `True` to refine towards the other end
"""
# some error tests on input
if n<=0:
raise ValueError('n should be greater than 0')
direction = check_direction(direction, obj.pardim)
if reverse:
obj.reverse(direction)
# fetch knots
knots = obj.knots()
knot_start = knots[direction][0]
knot_end = knots[direction][-1]
dk = knot_end - knot_start
# evaluate the factors
n = n+1 # redefine n to be knot spans instead of new internal knots
totProd = 1.0
totSum = 0.0
for i in range(n):
totSum += totProd
totProd *= alpha
d1 = 1.0 / totSum
knot = d1
# compute knot locations
new_knots = []
for i in range(n-1):
k = knot_start + knot*dk
if not knot_exists(knots[direction], k):
new_knots.append(k)
knot += alpha*d1
d1 *= alpha
# do the actual knot insertion
obj.insert_knot(new_knots, direction)
if reverse:
obj.reverse(direction)
return obj
def geometric_refine(obj, alpha, n, direction=0, reverse=False):
"""geometric_refine(obj, alpha, n, [direction=0], [reverse=False])
Refine a spline object by making a geometric distribution of element sizes.
:param obj: The object to refine
:type obj: :class:`splipy.SplineObject`
:param float alpha: The length ratio between two sequential knot segments
:param int n: The number of knots to insert
:param direction: The direction to refine in
:param bool reverse: Set to `True` to refine towards the other end
"""
# some error tests on input
if n <= 0:
raise ValueError('n should be greater than 0')
direction = check_direction(direction, obj.pardim)
if reverse:
obj.reverse(direction)
# fetch knots
knots = obj.knots()
knot_start = knots[direction][0]
knot_end = knots[direction][-1]
dk = knot_end - knot_start
# evaluate the factors
n = n + 1 # redefine n to be knot spans instead of new internal knots
totProd = 1.0
totSum = 0.0
for i in range(n):
totSum += totProd
totProd *= alpha
d1 = 1.0 / totSum
knot = d1
# compute knot locations
new_knots = []
for i in range(n - 1):
k = knot_start + knot * dk
if not knot_exists(knots[direction], k):
new_knots.append(k)
knot += alpha * d1
d1 *= alpha
# do the actual knot insertion
obj.insert_knot(new_knots, direction)
if reverse:
obj.reverse(direction)
return obj
def center_refine(obj, S, n, direction=0):
"""center_refine(obj, S, n, [direction=0])
Refine an object towards the center in a direction, by sampling an
tan function.
:param obj: The object to refine
:type obj: :class:`splipy.SplineObject`
:param float S: The slope of the tan function (range 0,pi/2)
:param int n: The number of knots to insert
:param direction: The direction to refine in
"""
# some error tests on input
if n <= 0:
raise ValueError('n should be greater than 0')
assert 0 < S < np.pi / 2
direction = check_direction(direction, obj.pardim)
# fetch knots
knots = obj.knots()
knot_start = knots[direction][0]
knot_end = knots[direction][-1]
dk = knot_end - knot_start
# compute knot locations
new_knots = []
max_tan = tan(S)
for i in range(1, n + 1):
xi = -1.0 + 2.0 * i / (n + 1)
xi *= S
k = knot_start + (tan(xi) + max_tan) / 2 / max_tan * dk
if not knot_exists(knots[direction], k):
new_knots.append(k)
# do the actual knot insertion
obj.insert_knot(new_knots, direction)
return obj
def edge_refine(obj, S, n, direction=0):
"""edge_refine(obj, S, n, [direction=0])
Refine an object towards both edges in a direction, by sampling an
arctan function.
:param obj: The object to refine
:type obj: :class:`splipy.SplineObject`
:param float S: The slope of the arctan function.
:param int n: The number of knots to insert
:param direction: The direction to refine in
"""
# some error tests on input
if n<=0:
raise ValueError('n should be greater than 0')
direction = check_direction(direction, obj.pardim)
# fetch knots
knots = obj.knots()
knot_start = knots[direction][0]
knot_end = knots[direction][-1]
dk = knot_end - knot_start
# compute knot locations
new_knots = []
max_atan = atan(S)
for i in range(1,n+1):
xi = -1.0 + 2.0*i/(n+1)
xi *= S
k = knot_start + (atan(xi)+max_atan)/2/max_atan*dk
if not knot_exists(knots[direction], k):
new_knots.append(k)
# do the actual knot insertion
obj.insert_knot(new_knots, direction)
return obj
