salome.sg.updateObjBrowser(0)
\endcode
+<br>
+\anchor tui_make_2dmesh_from_3d
+<h3>Create boundary elements</h3>
+
+\code
+# The goal of this feature is to enable the following use cases:
+# 1) The mesh MESH1 with 3D cells does not have or have only a part of its skin (2D cells):
+# 1.1) Add the 2D skin (missing 2D cells) to MESH1 (what it's done now by the algorithm).
+# 1.2) Create new 3D Mesh MESH2 that consists of MESH1 and added 2D skin cells.
+# 1.3) Create new 2D Mesh MESH3 that consists of only the 2D skin cells.
+# 2) The mesh MESH1 with 3D cells has all its skin (2D cells):
+# Create new 2D Mesh MESH3 that consists of only the 2D skin cells.
+#
+# In all cases an option to create a group containing these 2D skin cells should be available.
+
+from smesh import *
+
+box = geompy.MakeBoxDXDYDZ(1,1,1)
+geompy.addToStudy(box,"box")
+boxFace = geompy.SubShapeAll(box, geompy.ShapeType["FACE"])[0]
+geompy.addToStudyInFather(box,boxFace,"boxFace")
+
+MESH1 = Mesh(box,"MESH1")
+MESH1.AutomaticHexahedralization()
+
+init_nb_edges = MESH1.NbEdges()
+init_nb_faces = MESH1.NbFaces()
+init_nb_volumes = MESH1.NbVolumes()
+
+# =========================================================================================
+# 1) The mesh MESH1 with 3D cells does not have or have only a part of its skin (2D cells)
+# =========================================================================================
+# remove some faces
+all_faces = MESH1.GetElementsByType(SMESH.FACE)
+rm_faces = all_faces[:init_nb_faces/5] + all_faces[4*init_nb_faces/5:]
+MESH1.RemoveElements(rm_faces)
+assert(MESH1.NbFaces() == init_nb_faces-len(rm_faces))
+
+# 1.1) Add the 2D skin (missing 2D cells) to MESH1
+# -------------------------------------------------
+# add missing faces
+# 1.1.1) to the whole mesh
+m,g = MESH1.MakeBoundaryMesh(MESH1)
+assert(init_nb_faces == MESH1.NbFaces())
+assert(init_nb_edges == MESH1.NbEdges())
+assert(m)
+assert(not g)
+
+# 1.1.2) to some elements
+MESH1.RemoveElements(rm_faces)
+MESH1.MakeBoundaryMesh([])
+assert(init_nb_faces != MESH1.NbFaces())
+volumes = MESH1.GetElementsByType(SMESH.VOLUME)
+for v in volumes:
+ MESH1.MakeBoundaryMesh([v])
+assert(init_nb_faces == MESH1.NbFaces())
+assert(init_nb_edges == MESH1.NbEdges())
+
+# 1.1.3) to group of elements
+volGroup1 = MESH1.CreateEmptyGroup(SMESH.VOLUME, "volGroup1")
+volGroup1.Add( volumes[: init_nb_volumes/2])
+volGroup2 = MESH1.CreateEmptyGroup(SMESH.VOLUME, "volGroup2")
+volGroup1.Add( volumes[init_nb_volumes/2:])
+MESH1.RemoveElements(rm_faces)
+MESH1.MakeBoundaryMesh(volGroup1)
+MESH1.MakeBoundaryMesh(volGroup2)
+assert(init_nb_faces == MESH1.NbFaces())
+assert(init_nb_edges == MESH1.NbEdges())
+
+# 1.1.4) to submesh.
+# The submesh has no volumes, so check if it pass w/o a crash and does not create
+# missing faces
+faceSubmesh = MESH1.GetSubMesh( boxFace, "boxFace" )
+MESH1.RemoveElements(rm_faces)
+MESH1.MakeBoundaryMesh(faceSubmesh)
+assert(init_nb_faces != MESH1.NbFaces())
+
+# check group creation
+MESH1.RemoveElements(rm_faces)
+groupName = "added to mesh"
+m,group = MESH1.MakeBoundaryMesh(MESH1,groupName=groupName)
+assert(group)
+assert(group.GetName() == groupName)
+assert(group.Size() == len(rm_faces))
+
+
+# 1.2) Create new 3D Mesh MESH2 that consists of MESH1 and added 2D skin cells.
+# ------------------------------------------------------------------------------
+MESH1.RemoveElements(rm_faces)
+meshName = "MESH2"
+MESH2,group = MESH1.MakeBoundaryMesh(MESH1,meshName=meshName,toCopyElements=True)
+assert(MESH2)
+assert(MESH2.GetName() == meshName)
+assert(MESH2.NbVolumes() == MESH1.NbVolumes())
+assert(MESH2.NbFaces() == len(rm_faces))
+
+# check group creation
+MESH1.RemoveElements(rm_faces)
+MESH2,group = MESH1.MakeBoundaryMesh(MESH1,meshName="MESH2_0",
+ groupName=groupName,toCopyElements=True)
+assert(group)
+assert(group.GetName() == groupName)
+assert(group.Size() == len(rm_faces))
+assert(group.GetMesh()._is_equivalent(MESH2.GetMesh()))
+
+# 1.3) Create new 2D Mesh MESH3 that consists of only the 2D skin cells.
+# -----------------------------------------------------------------------
+MESH1.RemoveElements(rm_faces)
+meshName = "MESH3"
+MESH3,group = MESH1.MakeBoundaryMesh(MESH1,meshName=meshName,toCopyExistingBondary=True)
+assert(MESH3)
+assert(not group)
+assert(MESH3.GetName() == meshName)
+assert(MESH3.NbVolumes() == 0)
+assert(MESH3.NbFaces() == init_nb_faces)
+
+# check group creation
+MESH1.RemoveElements(rm_faces)
+MESH3,group = MESH1.MakeBoundaryMesh(MESH1,meshName=meshName,
+ groupName=groupName, toCopyExistingBondary=True)
+assert(group)
+assert(group.GetName() == groupName)
+assert(group.Size() == len(rm_faces))
+assert(group.GetMesh()._is_equivalent(MESH3.GetMesh()))
+assert(MESH3.NbFaces() == init_nb_faces)
+
+# ==================================================================
+# 2) The mesh MESH1 with 3D cells has all its skin (2D cells)
+# Create new 2D Mesh MESH3 that consists of only the 2D skin cells.
+# ==================================================================
+MESH1.MakeBoundaryMesh(MESH1)
+MESH3,group = MESH1.MakeBoundaryMesh(MESH1,meshName=meshName,toCopyExistingBondary=True)
+assert(MESH3)
+assert(not group)
+assert(MESH3.NbVolumes() == 0)
+assert(MESH3.NbFaces() == init_nb_faces)
+
+# check group creation
+MESH3,group = MESH1.MakeBoundaryMesh(MESH1,meshName=meshName,
+ groupName=groupName, toCopyExistingBondary=True)
+assert(group)
+assert(group.GetName() == groupName)
+assert(group.Size() == 0)
+assert(group.GetMesh()._is_equivalent(MESH3.GetMesh()))
+assert(MESH3.NbFaces() == init_nb_faces)
+
+# ================
+# Make 1D from 2D
+# ================
+
+MESH1.Clear()
+MESH1.Compute()
+MESH1.RemoveElements( MESH1.GetElementsByType(SMESH.EDGE))
+
+rm_faces = faceSubmesh.GetIDs()[:2] # to remove few adjacent faces
+nb_missing_edges = 2 + 2*len(rm_faces)
+
+MESH1.RemoveElements(rm_faces)
+mesh,group = MESH1.MakeBoundaryMesh(MESH1, BND_1DFROM2D)
+assert( MESH1.NbEdges() == nb_missing_edges )
+
+
+\endcode
*/
