In AGG for each layer one rule may be determined as trigger
for this layer. The so-called trigger rule is applied as
first and only once,
all other rules are applied as long as possible.
If the trigger rule is not applicable, the corresponding
layer is not executed at all.
A trigger rule can be set using item Set Trigger Rule for Layer of the GraGra pop-up menu. A table dialog Set Trigger Rule for Layer appears. Each layer may have at most one trigger rule that is set using check box Trigger.
In the gragra tree view, trigger rules are collored in red.
Trigger rule settings will be saved and loaded with the layered graph grammar.
Please note: In the table dialog Set Trigger Rule for Layer it is allowed to change layers of rules, too. Selecting or changing layers can effect also the trigger selections. So after changing a rule layer, the user needs to check the trigger definition and possibly reset it again.