.. role:: code
   :class: code

Trimmed Curve MbTrimmedCurve3D
==============================
.. _MbTrimmedCurve3D_Trimmed_Curve_:

.. kernel version: 118065

The :code:`MbTrimmedCurve3D` class is declared in the *cur_trimmed_curve3d.h* file.

A trimmed curve is defined by the base curve
:ref:`MbCurve3D <MbCurve3D_Curve_>` * **basisCurve**, the start parameter of trimming of the base curve
**trim1**, the end parameter of trimming of the base curve **trim2**, and
the flag of coincidence of the directions of the base curve and the trimmed curve
**sense**.

The trimmed curve coincides with the base curve on the segment defined by
the **trim1** and **trim2** parameters but can have the opposite
direction. If **sense** = 1, then
**trim1** < **trim2** and the trimmed curve coincides in
direction with the base curve. If **sense** = -1, then
**trim2** < **trim1** and the trimmed curve is directed opposite to
the base curve.

In the method

.. code-block:: cpp
   
   PointOn( double &         t,
            MbCartPoint3D  & r)

the radius vector of the curve **r** is described by the vector function

.. math::

   \mathbf{r}(t) = \mathbf{basisCurve}(trim1 + sense \cdot t).

The trimmed curve is shown in the figure:

.. figure:: ../../pictures/O.4.10.1.png
   :width: 12cm
   :align: center

The curve parameter *t* takes values on the segment

.. math::

   0 ≤ t ≤ sense \cdot (trim2 - trim1).

The trimmed curve can theoretically be used to change
the direction of a curve, but it is better to use the :code:`Inverse`\() method.

The trimmed curve can be used to change the position of the start
point of a periodic curve. For this, the base curve must be
periodic and **trim2** = **trim1** + **period**. In this case
the trimmed curve will also be periodic.

Another trimmed curve must not be used as a base curve
for a trimmed curve; the base curve of the latter must be used
with the corresponding recalculation of trimming parameters.

Each curve can build its own trimmed copy using the virtual method

.. code-block:: cpp

   Trimmed( double t1, double t2, int sense).