Export
Virtual Reality Modeling Language
There are two elements
to the VRML exporter, the Deisgner VRML Export
writes "Indexed face sets" to describe the vertices and faces in the
object model, the Animator VRML Export writes a VRML file that places
models in a scene adds a background and places viewpoints and paths that the
camera follows.
Deisgner
VRML Export
Use this option
to write VRML (.WRL) versions of the part of the model in the Designerthat is
currently selected. (Has its vertices selected). Use the Options to determine
whether the VRML file should have indendentations, and the number of digits
of accuracy used to write the VRML text. Any image maps may have an optional
prefix that replaces their file root.

Makes reading or
editing the VRML file in a text editor much easier to do. However it also makes
the files larger
Each Image map
is stored in with its full path stored in the model file. For VRML
Vertex coordinates
are written in a floating point format, with this option you can choose how
many digits of precision are used to write each coordinate. For example if 3
Digits of Precision are used the coordinates are written in the form 4.533,
16.732 etc.
Normals
A set of normals
at vertices can be generated based on the angles of faces next to each vertex.
Only faces that have their smoothing attribute set contribute to the vertex
normals.
Important
Notes
To build the most
efficient VRML representation from a Model the following conventions should
be noted and if possible followed:
- A separate VRML
shape is created for each entry in the skeleton hierarchy. Therefore a large
model should be divided into sub units and each individual one assigned to
a separate node (bone). This is essential if an image map is applied to any
faces in the model and will help in reducing the size of the VRML file if
multiple colors are applied to faces.
- Each face mesh
assigned to a skeleton node is tested to see if an image map is a applied
to any of the faces in the mesh. It is only possible to use one image map
for each group of faces assigned to a skeleton node therefore if your model
uses more than one image map or some of its faces are mapped and some not
then those faces which are mapped should be assigned to separate skeleton
nodes.
- Another important
step you must make before writing a VRML file that uses mapped surfaces and
that is all mapped surfaces must use Fixed-To mapping. If you have planar, cylindrical
or spherical mapped faces then mapping coordinates must be generated from
the the planar map etc.
- Reflection,
transmission and bump maps and textures are not exported to VRML.
- If a model contains
surfaces with a few different colors then the efficiency of the VRML file
will be improved if you group all faces using the same color and assign them
to one skeleton node. Doing this will enable the VRML writer to use a single
Material attribute for each shape rather then having to write a color index
for each face in the model.
Animator
VRML Export
The animator export
dialog offers a number of options some of whch are the same as the Designer
options:

The additional
animator options are:
- Viewpoints at
Camera Position Keyframes. A camera viewpoint which can be acessed by browsers
is written to the VRML file for every Position Keyframe of the active Camera.
- Interpolate
Camera With Time sensor. Position and Orientation Interpolators are written
for the active Camera at regular frame intervals throughout the animation.
- Background Environment
URLs Provide the names of six images that are used for the environment in
which the action takes place.
- If a Sky and
Ground are included in the animation then they will be represented in the
VRML output file.
VRML
References
Silicon Graphics.
vrml.sgi.com
VRML Resources,
Sites etc. Virtual
Reality - VRML
VRML Developer
Content Developer