userTrigger derived from ygSpace

Description: a space that generates events in the presence of a user head

notes:
Category: Trigger
Author: Dave Pape
Revision: 5/8/03

    Events
enter user, head a user has entered the space
exit user, head a user has exited the space
empty all users have exited the space
firstenter user, head a user has entered a previously empty space
    Debugs
inside
    Comments

constructor userTrigger

destructor ~userTrigger

method reset

1 clear set of users previously inside

method app

1 for each user in the world
1.1 if head is within the space
1.1.1 add to set of users inside
1.1.2 if inside but not previously then generate enter event
1.1.2.1 a user has entered the space
2 for each user previously inside
2.1 if not currently inside then generate exit event
2.1.1 a user has exited the space
3 if not previously empty and now empty generate empty event
3.1 all users have exited the space
4 if previously empty and now not empty generate firstenter event
4.1 a user has entered a previously empty space