Visual Basic.NET How to Program (PDF)

744 Graphics and Multimedia Chapter 16
Lines 55–59 disable txtLocation and enable the rest of the controls. Lines 62–64
set Genie as the default character, obtain all animation names via method GetAnimationNames
and then call IAgentCtlCharacter method Show to display the character.
We access characters through property Characters of mainAgent, which
contains all characters that have been loaded. We use the indexer of the Characters
property to specify the name of the character that we wish to load (Genie).
When a user clicks the character (i.e., pokes it with the mouse), event handler
mainAgent_ClickEvent (lines 93–100) executes. First, mSpeaker method Play
plays an animation. This method accepts as an argument a String representing one of the
predefined animations for the character (a list of animations for each character is available
at the Microsoft Agent Web site; each character provides over 70 animations). In our
example, the argument to Play is "Confused"—this animation is defined for all four
characters, each of which expresses this emotion in a unique way. The character then
speaks, "Why are you poking me?" via a call to method Speak. Finally, the Rest-
Pose animation is played, which returns the character to its neutral, resting pose.
The list of valid commands for a character is contained in the Commands property of
the IAgentCtlCharacter object (mSpeaker, in this example). The commands for an
Agent character can be viewed in the Commands pop-up window, which displays when
the user right-clicks an Agent character (the last screenshot in Fig. 16.37). Method Add of
the Commands property adds a new command to the command list. Method Add takes
three String arguments and two Boolean arguments. The first String argument identifies
the name of the command, which we use to identify the command programmatically.
The second String is optional and defines the command name as it appears in the Commands
pop-up window. The third String also is optional and defines the voice input
that triggers the command. The first Boolean specifies whether the command is active,
and the second Boolean indicates whether the command is visible in the Commands
pop-up window. A command is triggered when the user selects the command from the
Commands pop-up window or speaks the voice input into a microphone. Command logic
is handled in the Command event of the AxAgent control (mainAgent, in this example).
In addition, Agent defines several global commands that have predefined functions (for
example, speaking a character name causes that character to appear).
Method GetAnimationNames (lines 119–154) fills the actionsCombo
ComboBox with the current character’s animation listing and defines the valid commands
that can be used with the character. The method contains a SyncLock block to prevent
errors resulting from rapid character changes. The method obtains the current character’s
animations as an enumerator (125–127), then clears the existing items in the ComboBox
and character’s Commands property. Lines 136–147 iterate through all items in the animation
name enumerator. For each animation, in line 139, we assign the animation name to
String voiceString. Line 140 removes any underscore characters (_) and replaces
them with the String "underscore"; this changes the String so that a user can pronounce
and employ it as a command activator. The Add method (lines 145–146) of the
Commands property adds a new command to the current character. The Add method adds
all animations as commands by providing the following arguments: the animation name as
the new command’s name and voiceString for the voice activation String. The
method’s Boolean arguments enable the command, but make it unavailable in the Commands
pop-up window. Thus, the command can be activated only by voice input. Lines