.. role:: blue
   :class: blue

Construction of Equidistant Body
================================
.. _Construction_of_Equidistant_Body_:

.. kernel version: 118041

The function

.. code-block:: cpp

   MbResultType OffsetShell(       MbSolid &              solid,
                                   MbeCopyMode            sameShell,
                                   RPArray<MbFace> &      initFaces,
                                   bool                   checkFacesConnection,
                                   SweptValues &          p,
                             const MbSNameMaker &         operNames,
                                   bool                   copyFaceAttrs,
                                   MbSolid *&             result );

constructs an equidistant body for a set of faces.

Input parameters of the function are as follows:

- **solid** is an original body;
- **sameShell** is the copy mode of an original body;
- **initFaces** are faces of an original body;
- **checkFacesConnection** is the flag that checks the connection of selected faces:

  *true* -- the operation checks that all faces in **initFaces** form a single connected region; if the connectivity is violated, an error code is returned and the equidistant body is not constructed;

  *false* -- the check is not performed, which may lead to several disconnected parts of the result or to a failure of the operation;

- **p** is an object containing construction parameters;
- **operNames** is the operation namer;
- **copyFaceAttrs** is the flag for copying attributes from original faces to equidistant faces.

The function output parameter is the **result** parameter, which contains the constructed body.

The function returns a result code of the operation from the :blue:`MbResultType` enumeration (see *mb_operation_result.h*).

The function is declared in *action_shell.h* file.

The function constructs a body, the faces of which are equidistant to **initFaces** of the **solid** original body.

The **sameShell** parameter controls transfer of faces, edges and vertices from the **solid** original body to the **result** constructed body. This parameter can take one of four values:

- *cm_Same* = 0 (the shell is not copied);
- *cm_KeepHistory* (an original shell and its copy have the same basic surfaces, vertices, and faces unchanged by the operation);
- *cm_KeepSurface* (the original shell and its copy have the same basic surfaces);
- *cm_Copy* (the original shell and its copy do not have the same data).

The detailed description of the :blue:`MbeCopyMode` enumeration is located in section :ref:`Copying a Set of Faces <Copying_a_Set_of_Faces_>`.

The **p** parameter contains information about the distance between constructed faces and the original body faces. The distance can be equal to **p**.\ *thickness1* in positive direction or to **p**.\ *thickness2* in negative direction of the normal of the original body faces.

If **p**.\ *shellClosed* = *false*, then a non-closed body will be constructed.

The **p**.\ *checkSelfInt* parameter indicates the need to check a construction result for self-intersection. By default, **p**.\ *checkSelfInt* = *false* -- the check is not performed.

The **p**.\ *mergeFlags* flags control the merging of similar faces and edges (*true* -- merge similar elements).

The **operNames** parameter is used to name faces, edges and vertices of the constructed body.

Fig. 1 shows a body, its selected faces will be used to construct an equidistant body:

.. figure:: /MODELER/METHODS_OF_SOLID_BUILDING/pictures/M.1.15.1.png
   :width: 12cm
   :align: center

   Fig. 1

Fig. 2 shows the constructed equidistant body:

.. figure:: /MODELER/METHODS_OF_SOLID_BUILDING/pictures/M.1.15.2.png
   :width: 12cm
   :align: center

   Fig. 2

If the **initFaces** set contains all faces of the **solid** original body, the **result** constructed body will be equidistant to the **solid**.

The function :blue:`OffsetShell`\() adds :blue:`MbShellSolid` builder containing all construction data required into the body log. :blue:`MbShellSolid` constructor is declared in *cr_thin_shell_solid.h* file.

*Test.exe* test application allow to construct an equidistant non-closed body using «Create→Solid→Based on a solid→Offset solid» menu.