Collaborative Learning through Flexible Web CVE - Teaching through Multi-User Virtual Environments - page 480

Shared Objects this way, we can set up a particular avatar's figure

that is recognizable by others in the virtual word.

WebTalk04 architecture makes use of two dif-
ferent kinds of objects: on the one hand, we use
objects (typically embedded in the part file) that
are static geometrical files used to populate the
scene graph; on the other hand we use Shared
Objects that are deeply dynamic objects that can
interact with the other components in the collab-
orative session. Shared Objects are loaded and
instanced at start time. WebTalk04 architecture
can do mostly everything with this kind of object
because we can apply all the geometrical and
textures transformations. We can configure two
different Shared Objects Properties:

2. Relative Position and Orientation

With this set of properties we are able to finely
set up the start position, orientation and scale of
each avatar at the beginning of each session. So
we can specify all the geometric variables that
allow instancing a particular avatar in a particular
position (and particular geometrical peculiarity,
such as scale and orientation) during the scene
set up at start time.

3. Character Control Parameters

This set of properties can change an avatar's
physics parameters (mostly affecting its move-
ments). Here we can set up the avatar's walk
speed, run speed and mass.

1. Static Properties

In this XML section we set up the object's
geometrical configuration ( tags Geometry ), such
us the world position (X, Y, Z), the rotation (rotX,
rotY, rotZ) and other properties connected with
the shared object's appearance.

4. Animation Control Parameters

This parameters control the avatar's animation
properties. These properties are used to initialize
the module that governs the avatar's animation.
This high flexibility and reconfiguration easi-
ness is one of the key points to allows designers to
tailor specific graphical embodiments over each
user involved in the session, thus emphasizing
their sense of awareness of “being there”.
We can shape all the avatar's characteristics
so that users belonging to the same team (i.e. the
same class), have some graphical feature in the
virtual world, defined in Avatar Identification
Properties shown above, that visually associates
them together.
On the other hand, we can use one different
avatar (with different traits, skin, animations) for
each distinct user by simply associating the right
3D character model from an external geometries'
repository (grouped inside a component library).

2. Dynamic Properties

The dynamic properties ( tags Behaviors ) in-
volved with the interplay that the specific shared
object can have. Each Shared Object, in fact, inter-
acts with other objects in the world. Configuring
this XML node we describe how the shared object
reacts to external solicitations. In a few words, we
are able to fine set up all the behaviors that the
shared object can have dynamically.
As seen, our modular approach is based on the
hierarchical representation of entities (i.e. user
and objects), which makes simple the process of
populating the scene graph with shared objects
and assigns the right behavior in a particular col-
laborative context.

Virtual Actions

In WT04 architecture, all the collaboration issues
are configurable by a set of action that takes effect