.. role:: blue
   :class: blue

Constructing Two-Dimensional Compound Curve
===========================================
.. _Constructing_Two-Dimensional_Compound_Curve_:

.. версия ядра: 118047

The function

.. code-block:: cpp

   MbResultType CreateContour( MbCurve   & curve,
                               MbContour *& result );

constructs a compound curve (contour) based on an original curve.

**curve** original curve is an input parameter of the function.

The output parameter of the function is the pointer **result** containing a constructed curve.

If successful, the function returns :blue:`rt_Success`, otherwise it returns an
error code from :ref:`MbResultType <MbResultType_>`.

The function is declared in the *action_curve.h* file.

The function constructs **result** compound curve based on the
original **curve**. If the original **curve** is
also compound, then **result** curve will include the
components of the original curve. Two-dimensional compound curves are
described in Item :ref:`MbContour Two-Dimensional Contour <MbContour_Two-Dimensional_Contour_>`.

The function

.. code-block:: cpp

   MbResultType AddCurveToContour( MbCurve  &  curve,
                                   MbContour & contour,
                                   bool        toEnd,
                                   double      epsilon = METRIC_REGION );

modifies a compound curve by adding another curve.

The input parameters of the function are:

- **curve** — a curve to be added;
- **contour** — a compound curve to be modified;
- **toEnd** — the flag indicating the position to add the curve;
- **epsilon** — the point coincidence tolerance when adding the curve.

The output parameter of the function is the modified curve **contour**.

Upon successful completion, the function returns :blue:`rt_Success`; otherwise, it returns an error code from the :ref:`MbResultType_ <MbResultType_>` enumeration.

The function is declared in the *action_curve.h* file.

The function modifies the compound curve **contour** by adding the curve **curve** to the beginning or end of the compound curve.

If **toEnd** = *true*, the curve **curve** will be added to the end of the compound curve **contour**; if **toEnd** = *false*, the curve **curve** will be added to the beginning of the compound curve **contour**. The connection points of the modified curve and the added curve must coincide within the tolerance **epsilon**:

.. figure:: /MODELER/TWO-DIMENSIONAL_CURVE_CONSTRUCTION_METHODS/pictures/M.3.7.1.png
   :width: 12cm
   :align: center

If the added curve **curve** is a compound curve, its components will be added to the **contour** curve.