The Join command joins all selected compatible grid, database or source entities together into as few entities as possible. If selected entities belong to groups, the entity resulting from the join will become a member of all groups the original unjoined entities belong to. This command is implemented immediately without any command panel appearing. One exception to the latter will be joining of exactly two structured domains which share more than one physically separate edge (see below).


Tip: After joining two unstructured domains using the Join command, you may notice that the edges of several triangles create a line exactly where the shared connectors used to be. This can be fixed by selecting the domain and clicking on Initialize on the toolbar. The triangles will then be repopulated across the joined domain.

Select the entities to be joined, then Edit, Join. All currently selected entities of the same type are joined unless doing so would destroy topology. A mixed set of entity types can be selected and each type of the set will be joined into as few entities as possible. Note that selecting domains for joining will not automatically join their connectors, unless the connectors are selected as well.

There are a few restrictions on joining entities, as seen on the connector level above.

Three basic situations are shown in the figure above for connectors in which joining would destroy topology and therefore is not allowed:

  • When more than two connectors share a node
  • When there is a gap between connector nodes
  • When more than two connectors share a node (in the form of duplicate connectors)

These same rules can be extended to the joining of domains and blocks. Also note that a dimensioned connector cannot be joined with another one that is not dimensioned.

Results of joining structured domains and blocks will depend on the entity type selection, Grid, Set Type, such that if the Unstructured type is selected, the operation results in as few unstructured domains or blocks as possible. Otherwise when Structured is selected, as few structured domains or blocks as possible will be formed. Structured blocks containing degenerate cells due to containing poles or pole domains will not be joined into unstructured blocks. A successful join of structured domains or blocks into new structured domains or blocks will create a new subgrid for each of the original domains or blocks. It will also maintain the existing subgrids before the join if any.

A special Join panel appears with a list of possible linkages.
The selected linkage is highlighted in the Display window.

In the special case where exactly two structured domains are joined which share more than one physically separate edge, you will be presented with a Join panel which provides a list of the possible Domain Linkages at which the two domains can be joined. The linkage selected in the list will be highlighted in the Display window. Highlight the desired linkage and click OK to complete the join operation for the two domains.


Joining Connectors

Domain Join Linkage

Joining Structured Blocks