/*!

\page cartesian_algo_page Body Fitting 3D meshing algorithm

Body Fitting algorithm generates hexahedrones of a Cartesian grid in
the internal part of geometry and polyhedra and other types of
elements at intersection of Cartesian cells with the geometrical
boundary.

\image html cartesian3D_sphere.png "A shpere meshed by Body Fitting algorithm"

Algorithm of meshing is following.
<ol>
<li> Lines of a Cartesian structured grid defined by
\ref cartesian_hyp_anchor "Body Fitting Parameters" hypothesis are
intersected with the geometry boundary, thus nodes laying on the
boundary are found. This step also allows finding out for each node of
the Cartesian grid if it is inside or outside the geometry. </li>
<li> For each cell of the grid, check how many of it's nodes are outside
of the geometry boundary. Depending on a result of this check
<ul>
<li> skip a cell, if all it's nodes are outside </li>
<li> skip a cell, if it is too small according to <b> Size
    Threshold </b> paremeter</li>
<li> add a hexahedron in the mesh, if all nodes are inside </li>
<li> add a polyhedron or a cell of other type in the mesh, if some
nodes are inside and some outside </li> 
</ul>
</li>
</ol>
To apply this algorithm, when you define your mesh, select <b>Body
  Fitting</b> in the list of 3D algorithms and click <em>"Add
  Hypothesis"</em> button and <em>"Body Fitting Parameters"</em>" menu
  item. Dialog of <b> Body Fitting Parameters
  hypothesis</b> will appear.

<br>
\anchor cartesian_hyp_anchor
<h2>Body Fitting Parameters hypothesis</h2>

\image html cartesian3D_hyp.png "Body Fitting Parameters hypothesis dialog"

This dialog lets you define
<ul>
<li>\b Name of the algorithm </li>
<li> Minimal size of a cell truncated be the geometry boundary. If
  size of a truncated grid cell is \b Threshold times less than a
  initial cell size, then a mesh element is not created. </li>
<li> Cartesian structured grid. Each grid axis is defined
  individually. <b> Definition mode </b> chooses a way of grid
  definition: <ul> 
  <li> You can specify \b Coordinates of grid nodes. \b Insert button
    inserts a node at distance \b Step (negative or positive) from a
    selected node. \b Delete botton removes a selected node. Double
    click on a coordinate in the list enables its edition. A grid
    defined by \b Coordinates should enclose the geometry, else the
    algorithm will fail. </li>
  <li> You can define \b Spacing of a grid as an algebraic formular 
    <em>f(t)</em> where \a t is a position along a grid axiz
    normalized at [0.0,1.0]. The whole range of geometry can be
    divided into sub-ranges with their own spacing formulars to apply;
    \a t varies between 0.0 and 1.0 within each sub-range. \b Insert button
    divides a selected range into two ones. \b Delete button adds a
    selected sub-range to a previous one. Double click on a range in
    the list enables edition of its right boundary. Double click on a
    function in the list enables its edition. 
  </li> </ul>
</li>
</ul>

<br>
<b>See Also</b> a sample TUI Script of a 
\ref tui_cartesian_algo "Usage of Body Fitting algorithm".  

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