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https://github.com/NGSolve/netgen.git
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216 lines
8.3 KiB
Python
216 lines
8.3 KiB
Python
from netgen.meshing import *
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def ReadGmsh(filename):
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if not filename.endswith(".msh"):
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filename += ".msh"
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meshdim = 1
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with open(filename, '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, 'r')
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mesh = Mesh(dim=meshdim)
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pointmap = {}
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facedescriptormap = {}
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namemap = { 0 : "default" }
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materialmap = {}
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bbcmap = {}
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segm = 1
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trig = 2
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quad = 3
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tet = 4
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hex = 5
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prism = 6
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pyramid = 7
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segm3 = 8 # 2nd order line
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trig6 = 9 # 2nd order trig
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tet10 = 11 # 2nd order tet
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point = 15
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quad8 = 16 # 2nd order quad
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hex20 = 17 # 2nd order hex
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prism15 = 18 # 2nd order prism
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pyramid13 = 19 # 2nd order pyramid
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segms = [segm, segm3]
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trigs = [trig, trig6]
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quads = [quad, quad8]
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tets = [tet, tet10]
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hexes = [hex, hex20]
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prisms = [prism, prism15]
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pyramids = [pyramid, pyramid13]
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elem0d = [point]
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elem1d = segms
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elem2d = trigs + quads
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elem3d = tets + hexes + prisms + pyramids
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num_nodes_map = { segm : 2,
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trig : 3,
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quad : 4,
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tet : 4,
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hex : 8,
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prism : 6,
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pyramid : 5,
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segm3 : 3,
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trig6 : 6,
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tet10 : 10,
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point : 1,
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quad8 : 8,
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hex20 : 20,
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prism15 : 18,
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pyramid13 : 19 }
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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 not in num_nodes_map:
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raise Exception("element type", elmtype, "not implemented")
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num_nodes = num_nodes_map[elmtype]
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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 in elem1d:
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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 elem2d: # 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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if elmtype in trigs:
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ordering = [i for i in range(3)]
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if elmtype == trig6:
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ordering += [4,5,3]
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if elmtype in quads:
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ordering = [i for i in range(4)]
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if elmtype == quad8:
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ordering += [4, 6, 7, 5]
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mesh.Add(Element2D(index, [nodenums2[i] for i in ordering]))
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if elmtype in elem3d: # 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 in tets:
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ordering = [0,1,2,3]
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if elmtype == tet10:
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ordering += [4,6,7,5,9,8]
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elif elmtype in hexes:
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ordering = [0,1,5,4,3,2,6,7]
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if elmtype == hex20:
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ordering += [8,16,10,12,13,19,15,14,9,11,18,17]
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elif elmtype in prisms:
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ordering = [0,2,1,3,5,4]
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if elmtype == prism15:
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ordering += [7,6,9,8,11,10,13,12,14]
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elif elmtype in pyramids:
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ordering = [3,2,1,0,4]
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if elmtype == pyramid13:
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ordering += [10,5,6,8,12,11,9,7]
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mesh.Add(Element3D(index, [nodenums2[i] for i in ordering]))
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return mesh
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