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Last revision: 21 August 2013

This step by step guide explains how to run omegalib scripts on the EVL CAVE2 system. It is targeted at users that already have an account set up in the system. If you don't have an account check the Using the USB Drive section at the bottom of the page. For more information on python programming check the Python-Reference page, or the python reference section in the sidebar.

This guide can also serve as a basis for other cluster system setups.

Prerequisites

The user should have a personal account on the CAVE2 cluster, and should be able to ssh into the cluster head node. Furthermore, password-less ssh into other nodes in the cluster from the head node should be set up.

Step 1: setting the path

The omegalib user version is installed in /data/evl/omegalib-user. To simplify launching scripts from your account, you should add the binary folder from this install to your path. For instance, you can add the following lines to the .bashrc file in your home directory: NOTE To use OpenSceneGraph plugins (for instance to load obj files, .earth files etc), you will have to add the respective paths to the LD_LIBRARY_PATH variable.

	# Add the omegalib bin directory to path
	PATH=$PATH:/data/evl/omegalib-user/build/bin
	export PATH
	# (OPTIONAL) add the osg plugins path and the osgEarth binary path to LD_LIBRARY_PATH
	export LD_LIBRARY_PATH=/data/evl/osgearth/lib:/data/evl/omegalib-user/build/bin/osgPlugins-3.0.1

To see if you have done this correctly, log into into your account and type.

	> orun

This command should start omegalib on the cluster, showing a gray background on all screens. Your console should allow you to type in interactive python commands. For instance, if you type

	> sphere = SphereShape.create(1, 4)
	> sphere.setPosition(Vector3(0, 1.5, -2))

You should see a sphere towards the front of CAVE2.

Stopping orun

To stop orun, type oexit() at the console, or press control-C. If orun gets stuck or crashes on some nodes and you can't control it anymore, you can force a kill by opening another ssh connection to the head node and running

	> orun -K

This command will kill any orun instances you control on all nodes in the cluster.

Step 2: running scripts

Assume you have an omegalib script application in your home directory, into a directory called hello. If the main script for this application is called main.py, you can start it typing (from you home dir)

	> cd hello
	> orun -s main.py

It is important to launch the script from the root directory of your application, since omegalib will use that directory to resolve relative data paths for file lookups.

Step 3: using custom configurations

By default omegalib configures the system by looking up for a default.cfg configuration file. If the file is not found in you application directory, omegalib will use the one in /data/evl/omegalib-user/core/data. If you want to run a custom configuration in CAVE2, simply add a default.cfg file in your application directory. You can use this file to redirect the system configuration to a different file:

	config:
	{
		// We don't want to use this configuration file...
		//systemConfig = "evl/lyra-xinerama.cfg";
		
		// Let's use this instead.
		systemConfig = "system/desktop.cfg";
	};

Or you can directly write a full system configuration into your own default.cfg.

Random Notes

Sound in CAVE2

CAVE2 uses a supercollider sound serve that can be controlled with the sound API in the omega module. But sound applications that run on your desktop may need a small change to run in CAVE2. In CAVE2, only the head node controls the sound server, so all the display nodes will have their sound interface disabled. isSoundEnabled() returns False, and getSoundEnvironment() returns None on all nodes except the master. This may lead to script errors unless you check for sound support before running you sound code:

	# Check for sound support
	se = getSoundEnvironment()
	if(se != None):
		# DO sound stuff here ..

Fixing configuration

If when you start your program in CAVE2 it just displays on the head node, or on a subset of the CAVE2, that's likely because the wrong configuration has been set as default. Fixing this is easy, you just need to modify the default.cfg file under /data/evl/omegalib-user/core/data. The file will look similar to this:

	config:
	{
		systemConfig = "system/desktop.cfg";
		//systemConfig = "evl/lyra-xinerama.cfg";
		//systemConfig = "system/test-multipipe.cfg";
		//systemConfig = "system/cave-emu.cfg";
		//systemConfig = "system/test-multinode.cfg";
		//systemConfig = "system/test-customTile.cfg";
		//systemConfig = "system/test-wand-emulation.cfg";
		//systemConfig = "system/test-tracker.cfg";
	};

Make sure that the systemConfig = "evl/lyra-xinerama.cfg"; is the only uncommented line: in the example above, omegalib is configured to run in desktop mode.

Directory permissions

When launching orun you need to make sure you are running it from a directory on which you have write permissions. orun will need to create log files and Equalizer configuration files there. If your program segfaults immediately after running (i.e. before you see the ssh connection messages to the cluster nodes), the issue is probably due to incorrect directory permissions.

Using the USB Drive

If you want to quickly load a 3d model or script without manually uploading data to the CAVE2 cluster, you can use the USB Drive uploader. Plug in your usb drive in the cord next to the CAVE2 entrance and choose the USB Model Loader or USB Application launcher from the iPad menu.

Loading 3D Models

Your models need to be in .obj or .fbx format. Place them in your usb drive in a directory called omega/models. To organize your files you can create sub-directories, they will appear as sub-menus in the model loader.

Launching python scripts

Your script needs to be in the omega/apps directory. Each application should have its own folder. The application startup script should have the same name as the folder name. At startup, omegalib will show an on-screen menu with all the available applications listed.