The license should be GNU that is you can use the code in your own project only if you apply the same license (GNU).
In other words I think you cannot use it for commercial purpose unless you pay the license.
For OpenGL you can 'use' it with no restrictions.
This is only my (not legal) opinion :)

first off, you need to understand two things.

Number one, Copyrights and Patents are two different things and serve multiple purposes.

Copyright is to protect writers and authors from having their works stolen and redistributed without their permission. A book about Algebra is copyrighted, so that no one can make copies of the book without paying the author. In the software world, this is analagous to giving away free copies of a game or code without permission. However, a book written about algebra is very different from the IDEA of algebra. Because no one OWNS algebra, you are safe to use algebra in any way you see fit, even if an implementation of algebra (the book) is copyrighted.

Therefore, a game that uses cel-shading (like our book about math), for example, does not own the rights to cel-shading (the author does not own algebra), but owns the rights to control the implementation (the game, the book) that they have created.

However, there is another form of intellectual control, called a patent, that is designed to allow the inventor of something, (like the combustion engine) to control and (possibly) sell it's USE. This would be analogous to the INVENTOR of algebra, coming back from the dead and forcing EVERYONE in the world who uses algebra to pay him a patent license fee, regardless of whether or not he wrote the various books that use it, created the programs that use it, or built the computers that use it.

As you can see, a patent has far greater potential for control then a copyright does. To account for this, and to prevent everything from being controlled, our founding fathers made it inherently difficult to obtain these intellectual rights. In fact, Thomas Jefferson did not agree with the power patents gave to inventors, and was uneasy about their addition to the constitution. Now, however, copyright rules have changed, making it amazingly easy to get a copyright (you used to have to do the same application process to get one. Now you don't have to do anything). You still, however, have to go through a (theoretically) rigorous examination and investigation and application process in order to be given a patent. There are those who believe that software is not really patentable, and to do so is dangerous, but software patents are still valid today.

Now, on to your question.
Quake, like every single computer program in existance, is copyrighted(although quake 1and 2 are released under the gnu GPL). It is just like a book about math is copyrighted. However, none of the IDEAS used in a computer program are copyrighted, because they are just IDEAS. The only thing that could prevent you from using your own code YOU wrote to load an md2 format model would be if the format itself is PATENTED. This is highly unlikely, given the difficulty of obtaining a patent and the relative popularity of md2. However, it IS possible. I would do research to discover whether or not it is. MP3 is patented (damn MPAA), as are several other media formats.

In fact, because of the GPL, you can even use their model loader and displayer if you so choose, provided that you allow others to use your code in the same way. Copyleft is really like Pay it forward. If I give you rights, you must promise to give others that right. As a copyleft junkie, I highly recommend it as a way to greatly simplify the work you have to do to finish your indie project, in addition to greatly maximizing the popularity your project will recieve. It is awesome to find out that you can use great music in your games by finding works that are listed Attribution-Sharealike. I would start at CC. Remember, also, that there is a big misconception that GPL means that you cannot make any money off of your game or program. This is simply not true. While most GPL'ed projects are non-commercial, it is not only allowed, but ENCOURAGED to sell and make a living off of free software. Richard Stallman himself made money in the first days of the free software foundation by selling copies of emacs for 150$. This may seem silly, or against the GPL, but remember, you are not selling the right to use/read software, but only selling the action of making and sending a copy, and you can charge whatever you wish for this. You can also still offer a download version for free, but charge money for the act of getting a more advanced version (like shareware) or do anything else you want (without violating the GPL)

I guess I got on a rant here, sorry, but if you are with me so far, I would like to leave you explaining that yes, OpenGL is allowed to be used freely (hence 'Open'), and I also find it highly unlikely that the patent office would accept a patent on the equation (R+G+B)/3, so I think that you should be O.K. on those two issues.

and now you know!

Edit by Fruny: It's copyrighted not copywritten.

Do'h, the last one was me :)

Quote:Original post by Rasmadrak
Just curious, since ID has released the source code for quake1,2 , are they considered freeware? I mean, could I make an indie game (or retail) using their md2 file format (writing my own loader/displayer of course) ?

AFAIR, iD has said said that they will not sue anyone who writes their own model loader for md2 style models. Copying their code directly is not legal, but writting your own model loader should be fine.

IANAL, but I watch them on TV.

Quote:Is opengl freeware/royaltyfree even?

OpenGL is not a thing, it's a standard. Most OpenGL SDK's are 100% royalty free and free with a compiler. If you're programming on computer, then yes.