Event Triggers

There is some low-level link between the key bindings and the UI events. For example, in User.ini, under [Engine.input], we have the following line:

 Escape=SendEvent ShowMenus

This states that pressing escape will trigger ShowMenus. This relates to the following in U2Menus.ui

 [Root]
 Class=MultiStateComponent
 State=NonMain
 State=Main
 Transition=ResetMenus,0,0,0,NULL
 Transition=ShowMenus,1,1,0,NULL
 TriggerEvent=0,0.0,CodeMonkey,UnPause
 TriggerEvent=1,0.0,CodeMonkey,Pause
 TriggerEvent=1,0.0,Event,MenuBackgroundBlurry.FadeOut
 TriggerEvent=1,0.0,Event,MainMenuBackgroundLarge.Grow
 TriggerEvent=1,0.0,Event,MainMenuBackgroundSmall.Show
 DrawOrder=99
 Localize=true

The line:

 Transition=ShowMenus,1,1,0,NULL

defines this particular event.

I tested this by creating a useless event, which does the same thing as notifying you of a new objective. In U2HUD.ui, this defines the ObjectiveNotify component:

 [ObjectiveNotify]
 Class=MultiStateComponent
 State=NULL
 State=ObjectiveNotifyText
 Transition=NewObjective,1,0,4.0,ObjectiveNotifyText:NewObjective
 Transition=Honestly,1,0,4.0,ObjectiveNotifyText:Honestly
 Transition=ObjectiveCompleted,1,0,4.0,ObjectiveNotifyText:ObjectiveCompleted
 Transition=ObjectiveFailed,1,0,4.0,ObjectiveNotifyText:ObjectiveFailed
 TweenLocation=false
 TweenAlpha=true
 DrawOrder=1

I added the line in bold here. Then, I entered the corresponding keybinding in User.ini:

 F3=SendEvent Honestly

Finally, in U2HUD.int, the text is defined:

 [General]
 AutoTurret=Auto Turret
 RocketTurret=Rocket Turret
 FieldGenerator=Field Generator
 ProximitySensor=Proximity Sensor
 XMP_Unknown=Unknown
 Objectives=OBJECTIVES
 NewObjective=F4 - New Objective
 Honestly=Honestly!
 ObjectiveCompleted=F4 - Objective Completed
 ObjectiveFailed=F4 - Objective Failed
 EndGame_LoadMenu=Load menu
 EndGame_QuickLoad=Quick load
 EndGame_RestartLevel=Restart
 EndGame_Quit=QUIT
 Confirmation_Ok=Ok
 Confirmation_Cancel=Cancel
 Confirmation_QuickLoad=REALLY LOAD?

Thus, when I press F3 during the game, "Honestly!" appears in the bottom left corner of the screen.

Normally, Objective notify events will be triggered from UnrealScript - the U2GameInfo class, in function UpdateObjective()

switch(Status)
{
  case OBJECTIVE_Incomplete: class'UIConsole'.static.SendEvent("NewObjective"); break;
  case OBJECTIVE_Completed: class'UIConsole'.static.SendEvent("ObjectiveCompleted"); break;
  case OBJECTIVE_Failed: class'UIConsole'.static.SendEvent("ObjectiveFailed"); break;
}

This acheives exactly the same result, and the same native function must be called, if not from UnrealScript, in the first case I described.

MythOpus: I believe EventTriggers? are only used in Unreal 2 am I right?