.. _connect :

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> **_CONNECT_**

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>

>> Connect the nodes into a Delaunay tetrahedral or triangle grid. The
Delaunay criterion requires that the circumsphere (circumcircle) defined by
each tetrahedron (triangle) contains no mesh nodes in its interior. At present
only the **delaunay** option is implemented; this option will be the default.
The delaunay algorithm used requires that a "big tet" be constructed that
contains all nodes in its interior. The user has the option of providing the
coordinates of this "big tet". The user also has the option of selecting a
subset of nodes to connect.&nbsp_place_holder;&nbsp_place_holder; Connect will
by default detect material interfaces and will look for edges that intersect
the interfaces.&nbsp_place_holder; Nodes will be added to the mesh at these
intersections to create a conforming mesh.&nbsp_place_holder; This activity
may be turned off by using the **noadd** option.

  
The **check_interface** option is more expensive but does a more exhaustive
job of making sure there are no edges of the mesh that cross a material
boundary.

  
**Connect** may refuse to add nodes that will result in near zero-volume tetahedra. The volume tests are based on the mesh object epsilons. To ensure that these epsilons are based on the geometry, issue a **[setsize ](http://lagrit.lanl.gov/new_html/SETSIZE.html)**command before **[setpts](http://lagrit.lanl.gov/new_html/SETPTS.html)**.&nbsp_place_holder; Expert users may adjust the epsilons with the&nbsp_place_holder; [cmo/setatt](http://lagrit.lanl.gov/new_html/cmo_setatt.html)&nbsp_place_holder; command.&nbsp_place_holder; **Connect** will generate a 2D triangular mesh if both [**ndimensions_geom** and **ndimenions_topo**](http://lagrit.lanl.gov/new_html/meshobject.html) are 2.&nbsp_place_holder; In this case all nodes must lie in a plane.   
[Click here for more details on the connect
algorithm](http://lagrit.lanl.gov/new_html/connect_notes.html).

>>

>> The following instructions are for connecting points on a planar
surface.&nbsp_place_holder; The mesh must have **ndimensions_topo**=2 and
**ndimensions_geom**=2.

>>

>> **cmo**/**create/**trimesh///**tri**

**cmo**/**modatt**//**ndimensions_geom**/**default**/2   
...

**connect**
>>

>> an alternate way to achieve this is:

**cmo**/**create**/trimesh///**triplane**   
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**connect**   
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>

> FORMAT:

>

>> **connect**/[**delaunay**]/ifirst,ilast,istride/big_tet_coordinates

**connect**/**noadd****  
connect**/**check_interface**

>

> EXAMPLES:

>

>> **connect**

Create the Delaunay tetrahedral connectivity of all nodes in the mesh. Add
nodes to break multi-material connections.

**  
connect**/**delaunay**/

Create the Delaunay tetrahedral connectivity of all nodes in the mesh. Add
nodes to break multi-material connections.

**  
connect/delaunay**/1,0,0/ 0.,0.,0./1000.,0.,0./500.,1000.,0./500.,500.,10./

**connect/**1,0,0/ 0.,0.,0./1000.,0.,0./500.,1000.,0./500.,500.,10./noadd  
**connect/delaunay**/1,0,0/ 0.,0.,0./1000.,0.,0./500.,1000.,0./500.,500.,10./noadd  
**connect/delaunay**/1,0,0/ 0.,0.,0./1000.,0.,0./500.,1000.,0./500.,500.,10./check_interface  
Create the Delaunay tetrahedral connectivity of all nodes in the mesh and
specify explicitly the coordinates of the enclosing tetrahedron

**  
**connect/pset get points  
****Create the Delaunay tetrahedral connectivity of a subset of nodes.****  
  
******connect/noadd**  
Create the Delaunay tetrahedral connectivity of&nbsp_place_holder; all nodes
in the mesh and disregard material interfaces.

**  
connect/**check_interface****

Create the Delaunay tetrahedral connectivity of&nbsp_place_holder; all nodes
in the mesh with added checking of edges that have both nodes tagged as
itp='intrface' to be sure that the edge does not cross a material interface.
This option is more expensive but may fix situations where multi-material
edges do not get refined because they connect an 'intrface' node to an
'intrface' node.

>

> [Click here for 2D
demos](../../new_html/demos/2d_connect/test/html/main_2d_connect.html)

[Click here for 3D
demos](../../new_html/demos/connect/test/html/main_connect.html)

  
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