The Ygdrasil User's Guide

Running Ygdrasil Scenes

Many CAVE environments are created as single, standalone programs (like the crayoland demo). A program like this is called a CAVE App, short for application. Ygdrasil is an interpreter program that creates an environment from a text file, called a scene file. The scene file is written in the Ygdrasil language, a unique markup language with some similarities to languages like VRML or HTML.

Example Scenes

Ygdrasil comes with a few example scenes, which demonstrate different YG features.

1. open a shell
2. go into the system yg directory:
   
   $ cd /usr/local/yg
   
   this is where the yg application is.
3. look at what's in there:

   
   $ ls
   bergen  bin  bin.linux  bin.sgi  data  dso.linux  dso.sgi  examples  
   modules  README  repeater  RUN  src
   
   

   "examples" is a directory that contains example scenes. To see what's in there, you can say:
   
   $ ls examples
   
   
4. Run an example scene
   
   the file RUN is a script that runs the YG interpreter, sets up preferences, and tells it what scene file to load.
   
   $ ./RUN waves.scene
   
   you should get a bunch of stuff in the termninal, and a window with waves and a robotic claw-like thing. Try moving around and clicking the mouse buttons. To quit, press ESC. You can also click back into the terminal, and press CTRL-C.

• You must quit YG before running another scene.
• If you make changes to a scene, you have to quit YG and run it again to see the changes take effect.
• You can't do anything else in the terminal window while YG is running.
• Depending on how your shell preferences are set up, you may be able to say "RUN waves.scene" instead of "./RUN waves.scene". ./RUN is a very specific way of saying "look for the program RUN in the current directory.

(c) Ben Chang