netgen/python/geom2d.py

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from .libngpy._geom2d import SplineGeometry
from .meshing import meshsize
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unit_square = SplineGeometry()
_pnts = [ (0,0), (1,0), (1,1), (0,1) ]
_lines = [ (0,1,1,"bottom"), (1,2,2,"right"), (2,3,3,"top"), (3,0,4,"left") ]
_pnums = [unit_square.AppendPoint(*p) for p in _pnts]
for l1,l2,bc,bcname in _lines:
unit_square.Append( ["line", _pnums[l1], _pnums[l2]], bc=bcname)
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def MakeRectangle (geo, p1, p2, bc=None, bcs=None, **args):
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p1x, p1y = p1
p2x, p2y = p2
p1x,p2x = min(p1x,p2x), max(p1x, p2x)
p1y,p2y = min(p1y,p2y), max(p1y, p2y)
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if not bcs: bcs=4*[bc]
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pts = [geo.AppendPoint(*p) for p in [(p1x,p1y), (p2x, p1y), (p2x, p2y), (p1x, p2y)]]
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for p1,p2,bc in [(0,1,bcs[0]), (1, 2, bcs[1]), (2, 3, bcs[2]), (3, 0, bcs[3])]:
geo.Append( ["line", pts[p1], pts[p2]], bc=bc, **args)
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def MakeCircle (geo, c, r, **args):
cx,cy = c
pts = [geo.AppendPoint(*p) for p in [(cx,cy-r), (cx+r,cy-r), (cx+r,cy), (cx+r,cy+r), \
(cx,cy+r), (cx-r,cy+r), (cx-r,cy), (cx-r,cy-r)]]
for p1,p2,p3 in [(0,1,2), (2,3,4), (4, 5, 6), (6, 7, 0)]:
geo.Append( ["spline3", pts[p1], pts[p2], pts[p3]], **args)
def CreatePML(geo, pml_size, tol=1e-12):
"""Create a pml layer around the geometry. This function works only on convex geometries and
the highest existing domain number must be named by using the function geo.SetMaterial(domnr, name).
Points in the geometry are assumed to be the same if (pt1 - pt2).Norm() < tol.
Returned is a dict with information to create the pml layer:
normals: A dict from the names of the linear pml domains to the normal vectors pointing inside the pml."""
def Start(spline):
if spline.rightdom == 0:
return spline.StartPoint()
return spline.EndPoint()
def End(spline):
if spline.rightdom == 0:
return spline.EndPoint()
return spline.StartPoint()
splines = []
for i in range(geo.GetNSplines()):
splines.append(geo.GetSpline(i))
border = []
is_closed = False
current_endpoint = None
while not is_closed:
for spline in splines:
if spline.leftdom == 0 or spline.rightdom == 0:
if current_endpoint is not None:
if (Start(spline)-current_endpoint).Norm() < tol:
border.append(spline)
current_endpoint = End(spline)
if (current_endpoint - startpoint).Norm() < tol:
is_closed = True
break
else:
startpoint = Start(spline)
current_endpoint = End(spline)
border.append(spline)
break
else:
raise Exception("Couldn't find closed spline around domain")
endpointindex_map = []
for spline in border:
pnt = End(spline)
for i in range(geo.GetNPoints()):
if (pnt - geo.GetPoint(i)).Norm() < tol:
endpointindex_map.append(i)
break
else:
raise Exception("Couldn't find endpoint of spline in geometry")
start_ndoms = ndoms = geo.GetNDomains() + 1
new_spline_domains = []
normals = {}
duplicate_cnt = 0
for i, spline in enumerate(border):
if i == 0:
global_start = Start(spline) + pml_size * spline.GetNormal(0)
global_start_pnt = current_start = geo.AppendPoint(global_start[0], global_start[1])
next_spline = border[(i+1)%len(border)]
new_end = End(spline) + pml_size * spline.GetNormal(1)
spline_name = geo.GetBCName(spline.bc)
if "pml_" + spline_name in normals \
and normals["pml_" + spline_name] != spline.GetNormal(0):
duplicate_cnt += 1
spline_name = spline_name + "_duplicate_" + str(duplicate_cnt)
if (new_end - global_start).Norm() < tol:
new_spline_domains.append(ndoms)
geo.Append(["line", current_start, global_start_pnt], bc="outer_" + spline_name, leftdomain = ndoms)
geo.Append(["line", global_start_pnt, endpointindex_map[i]], leftdomain=ndoms, rightdomain=start_ndoms)
geo.SetMaterial(ndoms, "pml_" + spline_name)
normals["pml_" + spline_name] = spline.GetNormal(0)
ndoms += 1
break
end = geo.AppendPoint(new_end[0], new_end[1])
new_spline_domains.append(ndoms)
geo.Append(["line", current_start, end], bc="outer_" + spline_name, leftdomain = ndoms)
geo.Append(["line", end, endpointindex_map[i]], leftdomain=ndoms, rightdomain=ndoms+1)
geo.SetMaterial(ndoms, "pml_" + spline_name)
normals["pml_" + spline_name] = spline.GetNormal(0)
ndoms += 1
new_start = Start(next_spline) + pml_size * next_spline.GetNormal(0)
if (new_start - global_start).Norm() < tol:
geo.Append(["line", end, global_start_pnt], bc="outer", leftdomain = ndoms)
geo.Append(["line", global_start_pnt, endpointindex_map[i]], leftdomain=ndoms, rightdomain=start_ndoms)
geo.SetMaterial(ndoms, "pml_corner")
ndoms += 1
break
if (new_end - new_start).Norm() < tol:
current_start = end
else:
current_start = geo.AppendPoint(new_start[0], new_start[1])
geo.Append(["line", end, current_start], bc="outer", leftdomain = ndoms)
geo.Append(["line", current_start, endpointindex_map[i]], leftdomain=ndoms, rightdomain=ndoms+1)
geo.SetMaterial(ndoms, "pml_corner")
ndoms += 1
for spline, domnr in zip(border, new_spline_domains):
if spline.leftdom == 0:
spline.leftdom = domnr
else:
spline.rightdom = domnr
return {"normals" : normals}
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SplineGeometry.AddCircle = lambda geo, c, r, **args : MakeCircle(geo, c, r, **args)
SplineGeometry.AddRectangle = lambda geo, p1, p2, **args : MakeRectangle(geo, p1, p2, **args)
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SplineGeometry.AddSegment = lambda *args, **kwargs : SplineGeometry.Append(*args, **kwargs)
SplineGeometry.AddPoint = lambda *args, **kwargs : SplineGeometry.AppendPoint(*args, **kwargs)
SplineGeometry.CreatePML = CreatePML
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