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)
#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 """
t, dt = numpy.linspace(a0, a1, n_pts, retstep=True) # NOTE: could probably use an adaptive number of points
r0sin = r0 * numpy.sin(t)
r1cos = r1 * numpy.cos(t)
r0sin = (r0 + dr) * numpy.sin(t)
r1cos = (r1 + dr) * numpy.cos(t)
arc_dl = numpy.sqrt(r0sin * r0sin + r1cos * r1cos)
#arc_lengths = numpy.diff(t) * (arc_dl[1:] + arc_dl[:-1]) / 2
arc_lengths = (arc_dl[1:] + arc_dl[:-1]) * numpy.abs(dt) / 2
return arc_lengths, t
wh = self.width / 2.0
if num_vertices is not None:
n_pts = numpy.ceil(max(self.radii) / min(self.radii) * num_vertices * 100).astype(int)
perimeter_inner = get_arclens(n_pts, *a_ranges[0])[0].sum()
perimeter_outer = get_arclens(n_pts, *a_ranges[1])[0].sum()
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], dr=-wh)[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
max_arclen = min(implied_arclen, max_arclen if max_arclen is not None else numpy.inf)
assert max_arclen is not None
def get_thetas(inner: bool) -> NDArray[numpy.float64]:
""" 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)
arc_lengths, thetas = get_arclens(n_pts, *a_ranges[0 if inner else 1])
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], dr=dr)
keep = [0]
removable = (numpy.cumsum(arc_lengths) <= max_arclen)
@ -285,7 +286,6 @@ class Arc(Shape):
thetas = thetas[::-1]
return thetas
wh = self.width / 2.0
if wh in (r0, r1):
thetas_inner = numpy.zeros(1) # Don't generate multiple vertices if we're at the origin
else:
@ -455,17 +455,18 @@ class Arc(Shape):
def _angles_to_parameters(self) -> NDArray[numpy.float64]:
"""
Convert from polar angle to ellipse parameter (for [rx*cos(t), ry*sin(t)] representation)
Returns:
"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 = []
for sgn in (-1, +1):
wh = sgn * self.width / 2
wh = sgn * self.width / 2.0
rx = self.radius_x + 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)
sign = numpy.sign(self.angles[1] - self.angles[0])
if sign != numpy.sign(a1 - a0):