.. role:: blue
   :class: blue


MbItem Geometric Model Object
=============================
.. _MbItem_Geometric_Model_Object_:


.. kernel version: 


The :blue:`MbItem` class is declared in the *model_item.h* file.

The :blue:`MbItem` geometric model object is derived from the
:ref:`MbSpaceItem <MbSpaceItem_Three-Dimensional_Geometrical_Object_>`, :blue:`MbTransactions`, and :blue:`MbAttributeContainer` classes.
The C3D geometric kernel operates on geometric model objects
shown in Fig. 1.

.. figure:: /MODELER/OBJECTS_OF_GEOMETRIC_MODEL/pictures/O.8.1.1.png
   :width: 12cm
   :align: center

   Fig. 1

The :blue:`MbTransactions` construction journal contains the data required
to construct an object and allows you to repeat the construction of the object
with edited parameters. The MbAttrContainer attribute container
assigns attributes to geometric model objects. Thus, all geometric model
objects, in addition to their specific data, contain the following data:

size_t *m_countRegistrable* – the number of object registrations
during writing and reading,

ptrdiff_t *useCount* – the number of times the object is used by other
objects,

std::vector< MbCreator * > **transactions** – an ordered set of object builders,

std::multimap< int, MbAttribute * >
**attributes** – a set of object attributes.

The following geometric model objects are derived from the MbItem class:

:ref:`MbSolid <MbSolid_Solid_Body_>` – solid
body,

:ref:`MbWireFrame <MbWireFrame_Wireframe_>` – wireframe
model,

:ref:`MbPointFrame <MbPointFrame_Point_Frame_>` – point
frame,

:ref:`MbMesh <MbMesh_Polygonal_Object_>` – polygonal
object,

:ref:`MbInstance <MbInstance_Insertion_>` – insertion of a geometric model object,

:ref:`MbAssembly <MbAssembly_Assembly_Unit_>` – assembly
unit of geometric model objects,

:ref:`MbAssistingItem <MbAssistingItem_Auxiliary_Object_>` – auxiliary object,

:ref:`MbSpaceInstanсe <MbSpaceInstance_Three-Dimensional_Object_Insertion_>` – insertion of a three-dimensional object,

:ref:`MbPlaneInstanсe <MbPlaneInstance_Two-Dimensional_Object_Insertion_>` – insertion of a set of two-dimensional objects.

:ref:`MbPolymesh <Polygonal_Object_with_the_MbPolymesh_Topology_>` – polygonal object with topology.

The main methods of geometric model objects are methods
that provide editing and visualization of objects.

The method

bool :blue:`RebuildItem`\( MbeCopyMode sameShell,
RPArray<:ref:`MbSpaceItem <MbSpaceItem_Three-Dimensional_Geometrical_Object_>`>  **items** )

rebuilds the object according to the construction journal. This method
is called after editing the internal data of the object.

The method

MbItem * :blue:`CreateMesh`\( MbeStepData data, bool wire, bool grid, MbRegDuplicate * iReg )

creates a polygonal copy of the object. If the object is an
assembly unit or insertion, then the copy of the object will also be an
assembly unit or insertion containing polygonal objects.

The method

bool :blue:`AddYourMesh`\( MbeStepData data, bool wire, bool grid,
:ref:`MbItem <MbItem_Geometric_Model_Object_>` & **mesh** )

adds a polygonal copy of the object to the **mesh** object.

The method

bool :blue:`NearestMesh`\( MbeSpaceType sType, MbeTopologyType tType, MbePlaneType pType,
const MbAxis3D & **axis**, double maxDistance, double & t, double & dMin,
MbItem *& **find**, SimpleName & findName,
:ref:`MbRefItem <MbRefItem_Reference_Counter_>` *& **element**, SimpleName & elementName,
:blue:`MbPath` & path,
:ref:`MbMatrix3D <MbMatrix3D_Extended_Matrix_in_Three-Dimensional_Space_>` & **from** )

searches for the nearest polygonal object **find**, its
element **element**, their names findName and elementName, the path in
the assembly unit structure path, and the transformation matrix **from**
to the global coordinate system.

Geometric model objects overload the following methods of a three-dimensional
object:

methods that handle the transformation of a geometric object,

void :blue:`Move`\( const
:ref:`MbVector3D <MbVector3D_Vector_in_Three-Dimensional_Space_>` & **v**, MbRegTransform * iReg = NULL ),

void :blue:`Rotate`\( const MbAxis3D & **axis**, double
**angle**, MbRegTransform * iReg = NULL ),

void :blue:`Transform`\( const
:ref:`MbMatrix3D <MbMatrix3D_Extended_Matrix_in_Three-Dimensional_Space_>` & **m**, MbRegTransform * iReg = NULL ),

methods that provide copying, equality checking, checking the possibility
to make objects equal, and making objects equal,

:ref:`MbSpaceItem <MbSpaceItem_Three-Dimensional_Geometrical_Object_>` & :blue:`Duplicate`\( MbRegDuplicate * iReg = NULL ),

bool :blue:`IsSame`\( const :ref:`MbSpaceItem <MbSpaceItem_Three-Dimensional_Geometrical_Object_>` & **item** ),

bool :blue:`IsSimilar`\( const :ref:`MbSpaceItem <MbSpaceItem_Three-Dimensional_Geometrical_Object_>` & **item** ),

bool :blue:`SetEqual`\( const :ref:`MbSpaceItem <MbSpaceItem_Three-Dimensional_Geometrical_Object_>` & **item** ),

methods that return a type from the enumeration of geometric objects:

MbeSpaceType :blue:`IsA`\(),

MbeSpaceType :blue:`Type`\(),

MbeSpaceType :blue:`Family`\(),

methods that provide output and editing of the internal data
of the object:

MbProperty & :blue:`CreateProperty`\( MbePrompt name ),

:blue:`GetProperties`\( MbProperties & *properties* ),

:blue:`SetProperties`\( MbProperties & *properties* ).