Essential VRML Interview Questions & Answers:
VRML is useful for a variety of applications, including:
★ Data visualization
★ Financial analysis
★ Entertainment
★ Education
★ Distributed simulation
★ Computer-aided design
★ Product marketing
★ Virtual malls
★ User interfaces to information
★ Scientific visualization
2. What is the difference between VRML 1.0 and VRML 2.0?
The three main differences are that VRML 2.0 includes:
★ 3D sound
★ Interactivity
★ Object-oriented structure
Interactivity means that objects can move around and respond to the user's actions.
3. How to put VRML on a Web server?
You can FTP your VRML file onto a Web server, just as you would with an HTML file. The Web server will serve your file properly only if the MIME type is set up properly in the server.
The MIME type for VRML is "x-world/x-vrml". If you see a pile of text appear when you try to access your world from your server, that means the MIME type is not set up properly. E-mail your webmaster and ask them to set up the MIME type "x-world/x-vrml" for filename extension ".wrl".
In addition, to serve VRML files that have been compressed with GZIP properly, ask your webmaster to set up the Content Encoding type "x-gzip" for filename extension ".gz" (if it's not already set up).
There are now several browsers available for Macintoshes, and not just for PowerMacs either. Browsers for 68K Macs include ExpressVR, a Netscape plug-in, and Virtus Voyager, a stand-alone VRML viewer or helper application.
Netscape's Live3D for PowerMac is gradually becoming stable. Other PowerMac software includes ExpressVR, Voyager, Whurlwind, and Equinox.
All of the previous are VRML 1.0 browsers. The new kid on the block is RealSpace, with yes, a VRML 2.0 browser for PowerMacs.
5. How to combine VRML with Java and JavaScript?
There are several ways to combine VRML with Java and JavaScript. Netscape Live3D users can use Netscape's LiveConnect technology with Live3D to affect a VRML world in an HTML page from a JavaScript function or a Java applet. Conceivably, other browser developers could add LiveConnect interfaces.
In addition, VRML 2.0 has APIs for both Java and JavaScript, so that Java and JavaScript can be referenced through Script nodes. The Java and JavaScript can drive interactivity and other advanced features in the VRML world via the Script node and ROUTE-ing. Sony's Community Place VRML 2.0 browser supports the VRML 2.0 Java API. SGI's Cosmo Player VRML 2.0 browser supports the VRML 2.0 JavaScript API.
Other browsers may have their own Java APIs. Dimension X's Liquid Reality VRML 2.0 browser has its own Java API.
6. How to navigate through a VRML world?
There are three kinds of modes that most browsers have: fly, walk and point but each browser uses slightly different names or styles. In fly-like modes, it's like you are piloting a plane through a 3D space, arrow keys or mouse direction adjusts the direction you're headed in, and you also can move forward and (sometimes) backwards. Walk mode lets you move around on an imaginary flat surface, and you have to press special keys to move up and down.
Point mode is the best (maybe only?) excuse to use a mouse in navigating a VRML environment. You click on an object you see, and then you move towards it.
Another feature of VRML is that you can have preset viewpoints that a world creator positions to let you look at special vistas or views in the world. Think of it as a movie director positioning a camera while filming a scene. You can usually switch between these by right-clicking and making a selection from a pop-up menu. In addition, there can be links inside the VRML world that link to other parts of the world -- other viewpoints!
It takes a bit of getting used to, but you'll gradually get the hang of it.
7. How to make a VRML world have a small file size?
There is one simple way to drastically reduce the file size of your VRML world. You can reduce the file size by 80-90%!! You just need to compress it using GZIP.
GZIP is available for almost all available Unix platforms, plus other machines. Do a search at your favorite search engine to find a version for your machine.
In Unix, if you have gzip, you only need to type: gzip filename.wrl, and your file will become compressed and have the new filename filename.wrl.gz.
8. How to add behaviors without hand editing?
At this point, there are few VRML 2.0 authoring tools available that allow significant behaviors, so you're pretty much stuck using text editors. SGI's Cosmo Create includes some capability. Also, Paragraph's Virtual Home Space Builder provides the capability of creating VRML 2.0 compliant animated textures. Look for VRML 2.0 behavior-authoring software soon from Superscape.
9. How to have a VRML world in a frame link to other frames?
In VRML 2.0, you can use the parameters field of the Anchor node with the value "target=frame_name", where frame_name is the name of the frame to be targeted by the link. Note: In VRML 2.0 Draft 2 and earlier, the parameters field was previously called parameter.
Netscape's Live3D VRML 1.0 browser has an extension to VRML 1.0 that lets you target frames. The VRML navigation bar in VRMLSite uses this extension. You can add an extra field called target and give it an SFString value of the name of the frame. In addition, you will want to use a fields parameter in the WWWAnchor node.
To view VRML, you need a VRML browser, helper application or plug-in. The most commonly-used VRML 1.0 browser is Netscape's Live3D, which is available on Windows and PowerMac machines. Their are several VRML 2.0 browsers available in beta form. They include converters that let you view VRML 1.0 worlds as well. VRML 2.0 browsers include Dimension X's Liquid Reality, Silicon Graphics' Cosmo Player and Sony's Community Place (formerly known as Cyber Passage).
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