Back to the CaveUT Mainpage

Frequently Asked Questions About CaveUT and VRGL

by Jeffrey Jacobson, 13 June 2005


Wouldn't it be better to just have a single machine with multiple video cards?

No!

(1) Every time you add another display to a single computer, the load on the CPU, memory and the bus increace exponentially. You would save a little money on computer hardware if you only had two screens, but at three screens your central computer may be as expensive as four simple ones. Also, the more complex your single machine gets the greater the risk of problems. One of the primary advantages of CaveUT is that it can be used to drive up to 32 screens with only a linear increace in load on the server machine, and that load is small.

(2) The Unreal Engine (the heart of Unreal Tournament) is designed to run on a single display. Introducing the ability to support multiple displays with proper perspective correction, etc., would require making changes to the proprietary code in the Unreal Engine. (See next question.) Those changes could become extensive, and programmer time is quite expensive.

(3) Using one PC per screen requires only the typical PCs mass-produced for home and office use. They are cheap, easy to replace, easy to reuse for other purposes and (most importantly) well understood.


Is CaveUT just for making CAVEs?

CaveUT can do much more. It can drive up to 32 screens in any orientation to a single viewer, multiple CAVEs, a mix of CAVEs and single use consoles, or even a maze of screens. Each screen will


Would CaveUT be better if you modified the engine source code?

This is not an option for us, because the mission of the CaveUT project is to provide a low-cost open-source tool for the public. Even if we could somehow afford an open-source code license we could only distribute an engine-source version as an executable binary. Only a tiny number of game companies and scientific researchers who have Unreal Engine source code licenses could tweak the engine-based source code. That would cut 99.99% of everybody else out of the open-source development.


I have an engine source code license. What if I take some of the functionality of CaveUT into the game engine?

That's fine with us, as long as your project continues to reference the CaveUT project in the documentation, credits, and/or source code. Go the bottom of the page

http://planetjeff.net/ut/CaveUT.html

for details.

Technically, It might help you and it might not. It all depends on how you want to use CaveUT. Certainly, there is likely be some functions that work better with a source code modification, but make sure, first, before you start work. You should also be aware that any changes to the source code will have to be redone when the next version of engine comes out. Also, you run the risk of introducing bugs into the engine.


Does CaveUT do stereo and tracking?

The ALTERNE group has developed a stereographic, tracked, version of CaveUT. See

http://www.alterne.info/ http://planetjeff.net/IndexDownloads/Jacobson2005a.pdf

for more information. This will become the stereographic version of CaveUT, which we expect to release this fall.


Why don't you sell CaveUT for money?

We are only interested in developing CaveUT as a freeware tool for the public to use. All of the code, testing and documentation were donated by contributors with that understanding. All contributors are interested in using CaveUT for their own projects, and so have a stake in CaveUT's further development.

Furthermore, CaveUT would never have been profitable as a commercial application. The technology is too new and too easy to replicate. The market for a commercial product like this is too small.


What are the licensing issues with CaveUT?

The following section of this document in NO way superceedes the official CaveUT copyright, is packaged with the official distribution. The following description is only intended to introduce the ideas presented in the copyright and discuss the practical implications. This section does NOT constitute legal advice. It is the reader's responosibilty to examining the original CaveUT Copyright notice and Epic Games' End User Licence Agreement for Unreal Tournament

As far as we are concerned, you can use CaveUT for anything you want. All we ask is that you refer to us in the credits or somewhere in the documentation. How to do this is specified in the CaveUT copyright notice that comes with the distribution the full text is also at:

http://publicvr.org/ut/CaveUT.html

In fact, the only reason we even have a copyright for CaveUT is to prevent anyone else from patenting it and using that to restrict CaveUT's use or trying to extort money from users!

However, our CaveUT copyright does NOT limit your (or our) responsiblities under the the End User Licence Agreement which comes with all versions of Unreal Tournament. You should read it for yourself, but the main points is/are that

(1) Unless you buy a source code licence for the Unreal Engine, all your changes to the game's open source is also open source, and will stay that way forever.

(2) If you want to make money off of some use of UT (and therefore CaveUT) you have to clear it with Epic Games.

(3) If and only if your projects are non-commerical then, nobody (not even Epic) can prevent you from using the Unreal Engine by modifying the UT game source. Nor would they want to. Epic Games has always actively supported open-source development with the Unreal Engine. They are quite friendly to academic research projects.

(4) If you make something cool, Epic Games might incorprate it into the next version of the Unreal Engine. That's a good thing, because then they have to support it and it gives your project bragging rights. At worst it doesn't affect you


If you have further questions you'd like to see answered, please let me know: jeff@planetjeff.net

Back to the CaveUT Mainpage

Valid HTML 4.01!