Graphics Programs Reference
In-Depth Information
Sync Message” that tells all the clients to
switch the active metaphor to the new one.
All the clients update the new set of rules
that are effective.
This is a set of rules that are active only when
the selected (fixed) user is close to a particular
object: this is what we call Collaborative Metaphor.
The XML translation is shown in Algorithm 3.
Obviously, defining a huge number of meta-
phors and melting them together, we can govern
the collaborative environment recreating the exact
collaborative situation we wanted.
As seen above, thanks to the Collaborative
Metaphor paradigm, we are able to manage
complex interactions between entities in a virtual
shared environment, specifying the current set of
collaboration rules governing every aspect of the
virtual world.
Let us see now, how we can translate a com-
plex interaction rule in an XML-based description
used by WebTalk04 engine to control the mutual
interplays generated in/by the shared world.
Let us suppose we want to map this interac-
tion rule:
Network Communications
This node of the WT04 XML Schema allows us
to fine configure the network access. We use a
simple declarative approach that permits us to
easily decide which communication server we
have to use to share the experience state and a
set of properties that characterize the connection
between the specific client and the communica-
tion server. This is a list of the most important
parameters we can set up:
“When user Garibaldi is close to the gate, the
object named 'cube01' change its colour to
green on all the connected user's clients and all
the users are moved to the part number 2. When
this particular user left clicks on this object, the
system opens a browser window that links to the
url www.somewhere.net”
•
FCServer
: Communication Server IP num-
ber and the experience instance name.
•
FPSSharedUsers
: These values config-
ure the specific avatar position's upload
and download refresh rates. A high value
Algorithm 3. Fragment of the WT04 XML schema representing the instance of a collaborative metaphor
<Object Name=”Cube01” Physics=”Yes”>
<Geometry>
. . . . . . . . . . . . . . . . . .
</Geometry>
<Behavior>
<Metaphors>
<Metaphor num=”1”>
<User name=”Garibaldi”>
<OnLeftClick Far=”400”>
<Action Type=”GoToUrl” where=”www.somewhere.net”/>
</OnLeftClick>
<OnProximity Distance=”3000” Persistence=”0”>
<Action Type=”StarTrek” Property=”UsST2”/>
<Action Type=”ChangeColor” Target=”Cube01” Property=”#green”/>
</ OnProximity >
</User>
</Metaphor>
</Metaphors>
</Behavior>
</Object>
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