.. role:: blue
   :class: blue

Determining the Orientation of the Generatrix
==============================================
.. _Determine_the_Orientation_of_the_Generatrix_:

.. kernel version: 118059

The function

.. code-block:: cpp

   double AreaSign( const MbCurve3D &  curve,
                    const MbAxis3D &   axis,
                    const MbVector3D & direction,
                          bool         rotation )

computes the area of the projection of a curve onto a virtual coordinate plane to determine the orientation of a generatrix curve when subsequently constructing a body by extruding or revolving the generatrix curve. An open generatrix curve is closed by a segment for the calculation.

The input parameters of the function are:

- **curve** – the generatrix curve;
- **axis** – the axis of revolution (used for the revolution calculation);
- **direction** – the extrusion direction (used for the extrusion calculation);
- **rotation** – the flag specifying the operation type: *true* for revolution and *false* for extrusion.

The output of the function is the projection area of the curve.

The function is an auxiliary one for the :blue:`ExtrusionSolid`\(), :blue:`RevolutionSolid`\(), :blue:`ExtrusionResult`\() and :blue:`RevolutionResult`\() functions.