What I find very sad is that very little number of people knew about the technique before Carmack "discovered it".

I think the creators should have spread the word a bit more instead of patenting it.

[edited by - Gorg on September 21, 2003 11:05:14 PM]

Actually the "Practical and robust shadow volumes" paper on NVidia site mentions Bilodeau (the patent holder) as having noted in 1999 that reversing the depth comparison works too. They also say "We call Bilodeau and Carmack's approach zfail stenciled shadow volume rendering...".

I can understand a company wanting to protect a concept that it spent much time/money researching and that gives it a competitive edge - unfortunately there seems no good way to do that. One the one hand, patents don't work because they don't allow someone else who also spent much time/money researching in parallel from using their own invention (well aside from patents not being enforced and all that). On the other hand you can't prevent leaks.

I worked in a company that did speech compression that used Arithmetic Coding and near the end of the project we realised that it was patented by IBM. It was our mistake for not checking really (and we didn't come up with the idea ourselves) so we avoided the royalties and accepted the lower compression of Huffman. So I guess that means you need to check with the patents office whenever you use a technique or don't bother and hope nothing happens. Can you patent a software technique after you've published it ? I assume you can't because it's already in the public domain. Apparently some lady couldn't patent her wedding bouquet design because a picture of it was published in a newspaper.

[edited by - soiled on September 21, 2003 12:56:57 AM]

I figure that in this particular case since there are so many games out already that use this shadowing technique there is no way the patent holder can sue because they have allowed it to go on for so long. IIRC you must consistantly challenge patent violations in order to retain to right to do so. I may be totally wrong though. It just really sucks to have to worry about using all kinds of code because the idea/algorithm is patented and you might get sued for using it without a license. Where do you draw the line on what ideas merit a patent (e.g. Amazon sueing Barnes&Noble over "One click checkout" - I mean how simple of a concept is this?!)?

ATS

If I didn''t get it wrong, the Carmack''s reverse method, as people call it, is just an add-on technique to make shadow volumes more fast or robust, right?

Can such an "add-on technique" be patented as such? Because AFAIK the original paper on shadow volumes was published almost 25 years ago...

- Mikko Kauppila

In the US:
* Add-on techniques can be patented. Most patents are for modifications/extensions of previous techniques.
* You can choose to enforce against whom or when you want to. Previousl lapses don''t matter.
* If you''re shown (in court) to infringe, it''ll cost you damages.
* If you''re shown to _knowingly_ infringe, it''ll cost you triple damages.

Note that patents are very different from copyrights in these regards.

quote:Original post by Yann L

quote:Original post by cowsarenotevil
What about gameplay? Can the idea of say, an RPG, be patented, copyrighted, or neither?

Copyrighted, yes, absolutely. Your game design documents, scenarios, scripts, gameplay flowcharts, etc - all that is copyrighted.

But a patent is something different: you don''t patent a specific piece of work, but the concept or procedure used to create that work. The concept of an RPG (taking the role of different characters, with stats and all other usual character representations) could actually be patented. If I''m not mistaken, parts of the D&D fighting system is patented.

Although in the specific case of an entire genre, it has become common good by now. As such, it cannot be patented anymore.

AFAIK, Tetris GAMEPLAY is pantented... I don''t remember exactly the link, but they explain EXACTLY the normal tetris game... (of course, is patented in the US)

So technically, does this mean id Software and Carmack have to obtain a license to use a method he basically figured out???

This is crazy anyway.