plugin crack example in 3d

demos/api/crack3d.py

+import gmsh
+import sys
+
+gmsh.initialize(sys.argv)
+
+gmsh.option.setNumber("General.Terminal", 1)
+
+# create 2 adjacent boxes + a smaller surface on the interface
+v1 = gmsh.model.occ.addBox(0, 0, 0, 1, 1, 1)
+v2 = gmsh.model.occ.addBox(0, 0, -1, 1, 1, 1)
+s1 = gmsh.model.occ.addRectangle(0.25, 0.25, 0, 0.5, 0.5)
+
+# fragment the model to make the geometry conformal
+out, out_map = gmsh.model.occ.fragment([(2, s1)], [(3, v1), (3, v2)])
+
+# out_map contains the corresondence between the input and output entities after
+# fragmentation: out_map[0] will thus contain the entities (as (dim, tag) pairs)
+# replacing the surface s1
+
+# synchronize with the topological model
+gmsh.model.occ.synchronize()
+
+# define a physical group on the small surface (the "Crack" uses physical groups
+# as input)
+phys = gmsh.model.addPhysicalGroup(2, [out_map[0][0][1]])
+
+# generate conformal mesh
+gmsh.model.mesh.generate(3)
+
+# "crack" the mesh by duplicating the elements and nodes on the small surface
+gmsh.plugin.setNumber("Crack", "Dimension", 2)
+gmsh.plugin.setNumber("Crack", "PhysicalGroup", phys)
+gmsh.plugin.run("Crack")
+
+# save all the elements in the mesh (even those that do not belong to any
+# physical group):
+gmsh.option.setNumber("Mesh.SaveAll", 1)
+gmsh.write("crack.msh")
+
+# show the result
+if '-nopopup' not in sys.argv:
+    gmsh.fltk.run()
+
+gmsh.finalize()