jan/masque
1
1
Fork 0
Code Issues Pull Requests Releases Wiki Activity

Fixup arclength calculation for wedges (or other thick arcs)

Browse Source
This commit is contained in:
Jan Petykiewicz 2024-10-05 11:24:40 -07:00
parent febaaeff0b
commit 73193473df
1 changed files with 13 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
masque/shapes/arc.py
View File

@ -244,30 +244,31 @@ class Arc(Shape):
#t0 = ellipeinc(a0 - pi / 2, m) #t0 = ellipeinc(a0 - pi / 2, m)
#perimeter2 = r0 * (t1 - t0) #perimeter2 = r0 * (t1 - t0)
def get_arclens(n_pts: int, a0: float, a1: float) -> tuple[NDArray[numpy.float64], NDArray[numpy.float64]]: def get_arclens(n_pts: int, a0: float, a1: float, dr: float) -> tuple[NDArray[numpy.float64], NDArray[numpy.float64]]:
""" Get `n_pts` arclengths """ """ Get `n_pts` arclengths """
t, dt = numpy.linspace(a0, a1, n_pts, retstep=True) # NOTE: could probably use an adaptive number of points t, dt = numpy.linspace(a0, a1, n_pts, retstep=True) # NOTE: could probably use an adaptive number of points
r0sin = r0 * numpy.sin(t) r0sin = (r0 + dr) * numpy.sin(t)
r1cos = r1 * numpy.cos(t) r1cos = (r1 + dr) * numpy.cos(t)
arc_dl = numpy.sqrt(r0sin * r0sin + r1cos * r1cos) arc_dl = numpy.sqrt(r0sin * r0sin + r1cos * r1cos)
#arc_lengths = numpy.diff(t) * (arc_dl[1:] + arc_dl[:-1]) / 2 #arc_lengths = numpy.diff(t) * (arc_dl[1:] + arc_dl[:-1]) / 2
arc_lengths = (arc_dl[1:] + arc_dl[:-1]) * numpy.abs(dt) / 2 arc_lengths = (arc_dl[1:] + arc_dl[:-1]) * numpy.abs(dt) / 2
return arc_lengths, t return arc_lengths, t
wh = self.width / 2.0
if num_vertices is not None: if num_vertices is not None:
n_pts = numpy.ceil(max(self.radii) / min(self.radii) * num_vertices * 100).astype(int) n_pts = numpy.ceil(max(self.radii + wh) / min(self.radii) * num_vertices * 100).astype(int)
perimeter_inner = get_arclens(n_pts, *a_ranges[0])[0].sum() perimeter_inner = get_arclens(n_pts, *a_ranges[0], dr=-wh)[0].sum()
perimeter_outer = get_arclens(n_pts, *a_ranges[1])[0].sum() perimeter_outer = get_arclens(n_pts, *a_ranges[1], dr= wh)[0].sum()
implied_arclen = (perimeter_outer + perimeter_inner + self.width * 2) / num_vertices implied_arclen = (perimeter_outer + perimeter_inner + self.width * 2) / num_vertices
max_arclen = min(implied_arclen, max_arclen if max_arclen is not None else numpy.inf) max_arclen = min(implied_arclen, max_arclen if max_arclen is not None else numpy.inf)
assert max_arclen is not None assert max_arclen is not None
def get_thetas(inner: bool) -> NDArray[numpy.float64]: def get_thetas(inner: bool) -> NDArray[numpy.float64]:
""" Figure out the parameter values at which we should place vertices to meet the arclength constraint""" """ Figure out the parameter values at which we should place vertices to meet the arclength constraint"""
#dr = -self.width / 2.0 * (-1 if inner else 1) dr = -wh if inner else wh
n_pts = numpy.ceil(2 * pi * max(self.radii) / max_arclen).astype(int) n_pts = numpy.ceil(2 * pi * max(self.radii + dr) / max_arclen).astype(int)
arc_lengths, thetas = get_arclens(n_pts, *a_ranges[0 if inner else 1]) arc_lengths, thetas = get_arclens(n_pts, *a_ranges[0 if inner else 1], dr=dr)
keep = [0] keep = [0]
removable = (numpy.cumsum(arc_lengths) <= max_arclen) removable = (numpy.cumsum(arc_lengths) <= max_arclen)
@ -285,7 +286,6 @@ class Arc(Shape):
thetas = thetas[::-1] thetas = thetas[::-1]
return thetas return thetas
wh = self.width / 2.0
if wh in (r0, r1): if wh in (r0, r1):
thetas_inner = numpy.zeros(1) # Don't generate multiple vertices if we're at the origin thetas_inner = numpy.zeros(1) # Don't generate multiple vertices if we're at the origin
else: else:
@ -455,17 +455,18 @@ class Arc(Shape):
def _angles_to_parameters(self) -> NDArray[numpy.float64]: def _angles_to_parameters(self) -> NDArray[numpy.float64]:
""" """
Convert from polar angle to ellipse parameter (for [rx*cos(t), ry*sin(t)] representation)
Returns: Returns:
"Eccentric anomaly" parameter ranges for the inner and outer edges, in the form "Eccentric anomaly" parameter ranges for the inner and outer edges, in the form
`[[a_min_inner, a_max_inner], [a_min_outer, a_max_outer]]` `[[a_min_inner, a_max_inner], [a_min_outer, a_max_outer]]`
""" """
a = [] a = []
for sgn in (-1, +1): for sgn in (-1, +1):
wh = sgn * self.width / 2 wh = sgn * self.width / 2.0
rx = self.radius_x + wh rx = self.radius_x + wh
ry = self.radius_y + wh ry = self.radius_y + wh
# create paremeter 'a' for parametrized ellipse
a0, a1 = (numpy.arctan2(rx * numpy.sin(a), ry * numpy.cos(a)) for a in self.angles) a0, a1 = (numpy.arctan2(rx * numpy.sin(a), ry * numpy.cos(a)) for a in self.angles)
sign = numpy.sign(self.angles[1] - self.angles[0]) sign = numpy.sign(self.angles[1] - self.angles[0])
if sign != numpy.sign(a1 - a0): if sign != numpy.sign(a1 - a0):