nodeTrigger derived from ygSpace

Description: a space that generates events in the presence of a node

notes:
Category: Trigger
Author: Alex Hill
10/01/02
Revision: 09/01/04 Alex Hill - changed to detect by documented node name instead of alias used to create the node

    Messages
detect string set the type of node to detect
    Events
enter node the node has entered the space
exit node the node has exited the space
    Debugs
inside
    Comments

constructor nodeTrigger

destructor ~nodeTrigger

method reset

1 clear set of nodes previously inside

method message

1 set the type of node to detect

method setDetectType

method app

1 for each node of detect type in the world
1.1 if node is within the space
1.1.1 add to set of nodes inside
1.1.2 if inside but not previously then generate enter event
1.1.2.1 the node has entered the space
2 for each node previously inside
2.1 if not currently inside then generate exit event
3 the node has exited the space