mirror of
https://git.salome-platform.org/gitpub/modules/smesh.git
synced 2024-12-28 02:10:35 +05:00
101 lines
3.9 KiB
Plaintext
101 lines
3.9 KiB
Plaintext
/*!
|
|
|
|
\page about_meshes_page About meshes
|
|
|
|
\n \b MESH represents a discretization of a geometrical CAD model into
|
|
a set of entities with a simple topology.
|
|
|
|
Meshes are stored in DAT, MED and UNV formats and can be
|
|
\subpage importing_exporting_meshes_page "imported from and exported to"
|
|
the file in these formats.
|
|
|
|
However, it is possible to \subpage constructing_meshes_page "construct meshes"
|
|
on the basis of geometrical shapes produced in the GEOM module.
|
|
It is also possible to \subpage constructing_submeshes_page "create mesh on a part of the geometrical object",
|
|
for example, a face.
|
|
|
|
Several created meshes can be \subpage building_compounds_page "combined into mesh compounds".
|
|
|
|
The whole mesh or it's part can be \subpage copy_mesh_page "copied"
|
|
into another mesh.
|
|
|
|
All created meshes and submeshes can be \subpage editing_meshes_page "edited".
|
|
|
|
Meshes can be also edited using the MESH functions destined for
|
|
\ref modifying_meshes_page "modification" of generated meshes.
|
|
|
|
The \b topology of a mesh is described by the relationships between its
|
|
entities including:
|
|
|
|
<ul>
|
|
<li>\b Node — 0D object of a mesh presented by a point with coordinates (x, y, z).</li>
|
|
<li>\b 0D element — element of a mesh defined by one node.</li>
|
|
<li>\b Edge — 1D element of a mesh defined by two nodes.</li>
|
|
<li>\b Face — 2D element of a mesh defined by three or four edges (closed contour).</li>
|
|
<li>\b Volume — 3D element of a mesh defined by several faces.</li>
|
|
</ul>
|
|
|
|
These entities are
|
|
considered as topological entities and they don't
|
|
imply any geometric representation. Only \b Nodes reference geometric
|
|
representations of points with definite coordinates. The node entity
|
|
will contain additional information about its position in the space
|
|
and its relations with the meshed CAD model. Its position could be
|
|
described in the following way:
|
|
|
|
<ul>
|
|
<li><b>2D position</b>. It is a free position defined by only two coordinates x,y.</li>
|
|
<li><b>3D position</b>. It is a free position defined by three coordinates x,y and z. </li>
|
|
<li><b>Surface position</b>. It characterizes the position of a node on a
|
|
geometric surface and is defined by the u,v position in the parametric
|
|
space of the corresponding surface.</li>
|
|
<li><b>Line position</b>. It characterizes the position of a node on a
|
|
geometric curve and is defined by the u parameter and the
|
|
corresponding curve.</li>
|
|
<li><b>Vertex position</b>. It characterizes the position of a node on a
|
|
geometric point of the meshed CAD model and is defined by the x,y,z
|
|
coordinates of the corresponding vertex.</li>
|
|
</ul>
|
|
|
|
<br><h2>Connections</h2>
|
|
|
|
Each mesh entity bounds 0 or more mesh entities of higher
|
|
dimension. In the same way each mesh entity is bounded by 0 or more
|
|
mesh entities of lower dimension:
|
|
|
|
<ul>
|
|
<li>A node bounds edges, faces and volumes</li>
|
|
<li>An edge bounds faces, and volumes</li>
|
|
<li>A face bounds volumes</li>
|
|
<li>A volume is bounded by faces, edges and nodes</li>
|
|
<li>A face is bounded by edges, and nodes</li>
|
|
<li>An edge is bounded by nodes</li>
|
|
</ul>
|
|
|
|
You can notice that there are two types of connections: \b inverse and
|
|
\b direct connections.
|
|
|
|
<br><h2>Inverse connections</h2>
|
|
|
|
This relationship has a particularity that the order of bounded
|
|
entities has not a direct meaning. Also the number of bounded entities
|
|
is not fixed.
|
|
|
|
\b Example: The edges surrounding a node. The 3rd edge has no more
|
|
sense that the 5th one.
|
|
|
|
<br><h2>Direct connections</h2>
|
|
|
|
This relationship has a particularity that the order of bounding
|
|
entities is meaningful. The number of bounding entities is fixed and
|
|
depends on the type of the entity (hexahedron, tetrahedron,?).
|
|
|
|
\b Example: An edge is composed of two nodes. A face is composed of 3
|
|
or 4 edges depending if we are dealing with triangles or quadrangles.
|
|
|
|
The connections are not only restricted to entities of one dimension
|
|
higher or lower. For example some algorithms may be interested to
|
|
retrieve all the faces surrounding a node.
|
|
|
|
*/
|