5. VRML 2.0 Extensions and Enhancements

Compared to earlier versions 1.x five features seems remarkable.

• Enhanced static worlds
• Interaction
• Animation
• Scipts
• Prototyping

What do we mean by enhanced static worlds? You can add realism to the static geometry of existings worlds using new features of VRML 2.0

Now it is possible to create ground-and-sky backdrops to scenes, add distant mountains, clouds. Worlds seem more realistic because of irregular terrain nad 3D spatial sound can be added.

With VRML 2.0 interaction with the world is possible. You do not move through worlds like a ghost who can not touch, i.e. interact with the world's objects. Sensor nodes set off events when you enter certain areas. Collision-detection ensures that you can not walk or fly through solid objects. When following terrain, i.e. walking, you travel up and down according to the surrounding terrain. Other sensors keep track of the passage of time or trigger events at previously specified times.

Different Interpolators can be used to animate objects. You can create objects that move from one point to another, doors that open, robots that walk and whatever you can think of. Color interpolation could be used to create a sun that slowly get red while setting.

Scripts are used to give certain objects a behaviour. Without scripts birds could not fly and dogs would not be able to follow you when you are moving through the world. Generally scripts take inputs from sensors and generate events that change the world. The statements that are used to achive this are called routes

Changes from VRML 1.0 toVRML 2.0

• Grouping Nodes
• Collision Nodes tell the browser whether the specified geometries are solid or not.
• Transform Nodes group nodes together under a singel coordinate system. In VRML 1.0 Separator and Transform nodes were used therefore.
• Browser Information
• Background provides a shaded plane and/or distant geometry to be used as a backdrop, drawn behind the displayed scene.
• NavigationInfo provides hints to a browser about what kind of viewer to use. The most commen kinds of viewers are walk, examine and fly.
• Viewpoint replaces the former PerspectiveCamera node. It specifies an intersting location in a local coordinate system from which a user might wish to view the scene.
• WorldInfo can be used to store the scene's title and other important information like the authors or copyrights.
• Lights and Lighting
• Sound
• Sensors
• Proximity Sensors generate events when the camera moves within a bounding box of a specified size around a certain point.
• Touch Sensors generate events when the user clicks on specified geometry.
• Cylinder Sensors generate events that interpret user's click-and-drag on a virtual cylinder.
• Plane Sensors generate events that interpret user's click-and-drag on a virtual plane as a translation in 2D.
• Sphere Sensors generate events that interpret user's click-and-drag on a virtual sphere.
• Visibility Sensors generate events when regions enter or leave the users view.
• Time Sensors generate events at a given time or at specified intervals.
• Interpolation Nodes

VRML 1. 0 - VRML 2.0

#VRML V1.0 ascii

Transform{

translation T1

rotation R1

scale S

scaleOrientation R2

center T2

...

}

#VRML V2.0 utf8

Transform { translation T1

children [ Transform { translation T2

children [ Transform { rotation R1

children [ Transform { rotation R2

children [ Transform { scale S

children [ Transform { rotation -R2

children [ Transform { translation -T2

}]}]}]}]}]}]}

If you compare the VRML 1.0 code with the VRML 2.0 standard you see the differences. You should know by now what the VRML 1.0 listing does.

the difference in VRML 2.0 is that the grouping nodes (transform) have children (children [ ... ]). A list of nodes of descendant transformations are stored in those " children "

This page was created by Helmut Doleisch and Edgar Weippl on November 26, 1996.