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166 lines
6.6 KiB
Python
166 lines
6.6 KiB
Python
from netgen.meshing import *
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def ReadGmsh(filename):
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meshdim = 1
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with open(filename + ".msh", 'r') as f:
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while f.readline().split()[0] != "$Elements":
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pass
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nelem = int(f.readline())
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for i in range(nelem):
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line = f.readline()
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eltype = int(line.split()[1])
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if eltype > 1 and eltype != 15:
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meshdim = 2
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if eltype > 3 and eltype != 15:
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meshdim = 3
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break
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f = open(filename + ".msh", 'r')
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mesh = Mesh(dim=meshdim)
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pointmap = {}
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facedescriptormap = {}
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namemap = {}
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materialmap = {}
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bbcmap = {}
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while True:
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line = f.readline()
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if line == "":
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break
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if line.split()[0] == "$PhysicalNames":
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print('WARNING: Physical groups detected - Be sure to define them for every geometrical entity.')
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numnames = int(f.readline())
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for i in range(numnames):
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f.readline
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line = f.readline()
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namemap[int(line.split()[1])] = line.split()[2][1:-1]
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if line.split()[0] == "$Nodes":
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num = int(f.readline().split()[0])
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for i in range(num):
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line = f.readline()
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nodenum, x, y, z = line.split()[0:4]
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pnum = mesh.Add(MeshPoint(Pnt(float(x), float(y), float(z))))
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pointmap[int(nodenum)] = pnum
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if line.split()[0] == "$Elements":
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num = int(f.readline().split()[0])
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for i in range(num):
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line = f.readline().split()
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elmnum = int(line[0])
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elmtype = int(line[1])
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numtags = int(line[2])
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# the first tag is the physical group nr, the second tag is the group nr of the dim
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tags = [int(line[3 + k]) for k in range(numtags)]
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if elmtype == 1: # 2-node line
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num_nodes = 2
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elif elmtype == 2: # 3-node trig
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num_nodes = 3
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elif elmtype == 3: # 4-node quad
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num_nodes = 4
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elif elmtype == 4: # 4-node tet
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num_nodes = 4
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elif elmtype == 5: # 8-node hex
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num_nodes = 8
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elif elmtype == 6: # 6-node prism
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num_nodes = 6
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elif elmtype == 7: # 5-node pyramid
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num_nodes = 5
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elif elmtype == 15: # 1-node point
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num_nodes = 1
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else:
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raise Exception("element type", elmtype, "not implemented")
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nodenums = line[3 + numtags:3 + numtags + num_nodes]
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nodenums2 = [pointmap[int(nn)] for nn in nodenums]
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if elmtype == 1:
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if meshdim == 3:
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if tags[1] in bbcmap:
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index = bbcmap[tags[1]]
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else:
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index = len(bbcmap) + 1
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if len(namemap):
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mesh.SetCD2Name(index, namemap[tags[0]])
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else:
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mesh.SetCD2Name(index, "line" + str(tags[1]))
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bbcmap[tags[1]] = index
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elif meshdim == 2:
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if tags[1] in facedescriptormap.keys():
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index = facedescriptormap[tags[1]]
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else:
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index = len(facedescriptormap) + 1
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fd = FaceDescriptor(bc=index)
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if len(namemap):
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fd.bcname = namemap[tags[0]]
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else:
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fd.bcname = 'line' + str(tags[1])
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mesh.SetBCName(index - 1, fd.bcname)
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mesh.Add(fd)
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facedescriptormap[tags[1]] = index
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else:
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if tags[1] in materialmap:
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index = materialmap[tags[1]]
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else:
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index = len(materialmap) + 1
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if len(namemap):
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mesh.SetMaterial(index, namemap[tags[0]])
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else:
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mesh.SetMaterial(index, "line" + str(tags[1]))
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materialmap[tags[1]] = index
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mesh.Add(Element1D(index=index, vertices=nodenums2))
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if elmtype in [2, 3]: # 2d elements
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if meshdim == 3:
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if tags[1] in facedescriptormap.keys():
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index = facedescriptormap[tags[1]]
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else:
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index = len(facedescriptormap) + 1
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fd = FaceDescriptor(bc=index)
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if len(namemap):
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fd.bcname = namemap[tags[0]]
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else:
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fd.bcname = "surf" + str(tags[1])
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mesh.SetBCName(index - 1, fd.bcname)
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mesh.Add(fd)
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facedescriptormap[tags[1]] = index
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else:
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if tags[1] in materialmap:
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index = materialmap[tags[1]]
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else:
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index = len(materialmap) + 1
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if len(namemap):
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mesh.SetMaterial(index, namemap[tags[0]])
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else:
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mesh.SetMaterial(index, "surf" + str(tags[1]))
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materialmap[tags[1]] = index
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mesh.Add(Element2D(index, nodenums2))
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if elmtype in [4, 5, 6, 7]: # volume elements
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if tags[1] in materialmap:
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index = materialmap[tags[1]]
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else:
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index = len(materialmap) + 1
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if len(namemap):
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mesh.SetMaterial(index, namemap[tags[0]])
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else:
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mesh.SetMaterial(index, "vol" + str(tags[1]))
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materialmap[tags[1]] = index
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nodenums2 = [pointmap[int(nn)] for nn in nodenums]
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if elmtype == 4:
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mesh.Add(Element3D(index, [nodenums2[0], nodenums2[1], nodenums2[3], nodenums2[2]]))
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elif elmtype in [5, 6, 7]:
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mesh.Add(Element3D(index, nodenums2))
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return mesh
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