Can commercial engines be used for open source games?

Can commercial engines be used for open source games?

Postby rogerdv » 18 Jun 2014, 15:25

I was wondering if it is possible to create open source games with commercial engines like Unity3d or UE. Even when the game source code could be available, the engine source wont. What do you think about it?
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Re: Can commercial engines be used for open source games?

Postby devnewton » 18 Jun 2014, 15:30

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Re: Can commercial engines be used for open source games?

Postby onpon4 » 18 Jun 2014, 16:59

It's possible and probably legal (depends on the license of the engine), but why? It's not free/libre or "open source" in any meaningful sense, then, unless someone undertakes the task of developing a compatible free/libre replacement for the engine. Please use free/libre engines, like the Blender Game Engine or ENIGMA.
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Re: Can commercial engines be used for open source games?

Postby rogerdv » 18 Jun 2014, 19:39

onpon4 {l Wrote}:It's possible and probably legal (depends on the license of the engine), but why? It's not free/libre or "open source" in any meaningful sense, then, unless someone undertakes the task of developing a compatible free/libre replacement for the engine. Please use free/libre engines, like the Blender Game Engine or ENIGMA.


BGE is not the best choice as engine. Other open source solutions lack the power of commercial engines, except for Torque 3d, and it is so dificult to underestand in the beginning that I lost any wish to use it when I try to do some programming related taks, like implementing an item or dialog system.
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Re: Can commercial engines be used for open source games?

Postby Julius » 18 Jun 2014, 20:21

While I agree on BGE (it's more or less abandoned by the Blender Foundation, and never was that great in the first place), the question is what you mean by "power". Sure commercial engines look shiny and come with all bells&whistles, but that swiss army kind of design comes at a price, i.e. most of them are overly complex especially for the games you are likely to create as a hobbyist or indie-developer. Torque3D is maybe one of the worst examples of that.

On the other hand, I agree that open-source engines mostly lack a certain degree of polish that allows you to just dabble around with things, like you would when modding a commercial game. However there are some positive examples otherwise.
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Re: Can commercial engines be used for open source games?

Postby rogerdv » 18 Jun 2014, 21:00

By "power" I mean that you get an integrated development environment where you spend 15 minutes importing assets and seting up a simple scene, including collisions and all the fancy stuff, and start coding. I spent 3 years with Ogre, trying to put together third party addons with few or not at all support. CrystalSpace didnt even had a decent exporter! Irrlicht was a weird mix of open source components with a few (the most important) commercial. An integrated scene editor seems to be an optional component in the open source world. there are a few engines changing that, but they are in a early stage (Urho3d even fails to import assets if file name or path includes spaces, and the editor looks like the first Tron movie).
WE are seeing more indie and free games because the game development technology has improved. But open source technology is still tied to the past.
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Re: Can commercial engines be used for open source games?

Postby Julius » 18 Jun 2014, 21:15

Hmm, yes that would certainly be nice (had a look at Godot though?). But it depends on the type of game you want to create. Scene editors are nice for quickly slapping some assets together (for lets say a 3d single player prototype), but for many game types you would rather have a proper (build in) level editor (see good examples like 0AD or Tesseract). And for managing stuff like player models I have learned that simple text config-files and well working exporters using standard formats are much preferable over messy stuff like trying to import a collada/fbx file into the development environment.
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Re: Can commercial engines be used for open source games?

Postby Arthur » 18 Jun 2014, 22:02

Not sure if 0ad is a good example here (well they are, just not in this context I think), as they made (or had to make) their own engine from scratch. And rogerdv is completely right, many open source engines need an excessive amount of tweaking to make them usable for pretty much any game (the shooters seem to have the most complete engines for their genre). Quite sad as we're losing out on a lot of hobbyist developers that might be happy to release as open source if they were more familiar with the concept.
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Re: Can commercial engines be used for open source games?

Postby Evropi » 18 Jun 2014, 22:08

It is not a good idea. Fr1tz, whose crowdfunding campaign I've contributed to, had a good 60-70% of the work already done. That's why it will take a few months to get an alpha release of Terminal Overload out, instead of years. By contrast, the Trillek project estimated from the start that it would take them 2-3 years to finish just the engine alone.

What is sad is that there are so many open source engines out there, but no one comprehensive, well-documented and easy-to-use toolchain yet, not that developers refuse to reinvent the wheel.
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Re: Can commercial engines be used for open source games?

Postby Sauer2 » 18 Jun 2014, 22:17

Julius {l Wrote}:Hmm, yes that would certainly be nice (had a look at Godot though?). But it depends on the type of game you want to create. Scene editors are nice for quickly slapping some assets together (for lets say a 3d single player prototype), but for many game types you would rather have a proper (build in) level editor (see good examples like 0AD or Tesseract). And for managing stuff like player models I have learned that simple text config-files and well working exporters using standard formats are much preferable over messy stuff like trying to import a collada/fbx file into the development environment.

As much as I don't like mods which require proprietary engines, rogerdv has a point.
Tooling is miserable in most open source engines and beside 0AD and Tesseract, Anura is the only approachable engine I know of. Most open source engines suffer either from being very old (from a time where tooling was unnecessary luxus like in the original C-Dogs) or is specialized to a certain aspect like graphics.
Compare that to, say, Unreal4 where you can do about everything in the editor.

Speaking of Tesseract: As far as I know, it's Sauerbraten with better graphics. Have they improved the editor, too? For example, is scripting and particle effect creation been improved?
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Re: Can commercial engines be used for open source games?

Postby onpon4 » 18 Jun 2014, 22:29

BGE is just one that I know of (I'm not very knowledgeable about 3-D game engines, or anything related to 3-D really).

Other open source solutions lack the power of commercial engines, except for Torque 3d, and it is so dificult to underestand in the beginning that I lost any wish to use it when I try to do some programming related taks, like implementing an item or dialog system.


Some people, like Linus Torvalds, consider freedom to be only a minor point to consider. This is the open source movement. Others, like Richard Stallman, value freedom above all. This is the free/libre software movement.

The way you talk suggests to me you're a part of the former group. If that's the case, I don't know why you're trying to justify yourself. However, if you are a part of the latter group, a proprietary engine being better than any free/libre engine is never even a remotely valid excuse for using the proprietary engine. Also keep in mind that, since this is software development, your choice of engine doesn't only affect you; it directly affects your users (those who play the game) as well.
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Re: Can commercial engines be used for open source games?

Postby rogerdv » 19 Jun 2014, 12:24

Well, lets go back to the point: is it technically possible, despite philosophical/ethical issues? under XGPL license, or Whatever license? Or simply impossible?
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Re: Can commercial engines be used for open source games?

Postby Julius » 19 Jun 2014, 13:22

Of course it is possible with a license that is non-copyleft. MIT/BSD etc.

When you are distributing it independently (and don't base you work on some modding SDK) a copy-left license would also be possible, but a bit questionable (same as distributing a closed source mod for a GPL engine).

But really, what is the point? It's nothing better than "shared source" without a license in the end.
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Re: Can commercial engines be used for open source games?

Postby rogerdv » 19 Jun 2014, 14:24

Just wanted to know if it is possible. It means that we can use unity3d (standard or pro) to build an open source game.
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Re: Can commercial engines be used for open source games?

Postby Julius » 19 Jun 2014, 16:15

rogerdv {l Wrote}:It means that we can use unity3d (standard or pro) to build an open source game.


Not really, as the engine is closed source. What you can do is to make the source of your game specific script available under an open-source license. Maybe you could call it an open-source mod ;)
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Re: Can commercial engines be used for open source games?

Postby devnewton » 24 Jun 2014, 08:19

rogerdv {l Wrote}:Just wanted to know if it is possible. It means that we can use unity3d (standard or pro) to build an open source game.


It is possible, but pointless. And it will be an open source game, but not a "libre" game.

Try http://jmonkeyengine.org/, http://www.polycode.org/ or http://www.maratis3d.com/ if you want something like unity.
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Re: Can commercial engines be used for open source games?

Postby mdwh » 28 Jun 2014, 12:08

I don't think it's pointless, and is better than "source-available". Developers can still look and more importantly use the code, where as with source-available you can look but can't use it in Open Source (and indeed, merely looking may be a liability, as it opens you to accusations that you copied). Similarly with Free artwork, that art is Free to be used for other purposes.

Sure, it's better for the game as a whole to be Open Source. It means the game can be distributed with all the freedoms of Open Source (including commercial), and makes things easier for distribution through Free channels like Linux repositories. It means people can edit the engine and not just the Open Source part of the game. But still, sometimes people have to be pragmatic - making games is hard and timeconsuming enough as it is, without having to ignore what might be the best tools available, and I'd rather they still release the things that they do under Free licences rather than thinking it pointless.

The distinction between "mod" and "game" can be a bit blurred, but I don't think the distinction should be based on the licencing. If I took an Open Source game and modified something, we'd still call it a mod. If someone licences a closed source engine and builds a whole new game on top of that, we typicall call that a game in its own right. It doesn't suddenly become a "mod" if they Open Source their code.

Is there a way to be able to use tools like from Unity with Open Source engines? Perhaps an approach is to make better exporter/importers to be able to translate models into Open Source engines (or into open standards like Collada, or something that can be read by Open libraries like ASSIMP).
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Re: Can commercial engines be used for open source games?

Postby farcodev » 20 Jul 2014, 15:57

from UE's license:

"You may not combine, Distribute, or otherwise use the Licensed Technology with any code or other content which is covered by a license that would directly or indirectly require that all or part of the Licensed Technology be governed under any terms other than those of this Agreement (“Non-Compatible License”). Code or content under the following licenses, for example, are prohibited: GNU General Public License (GPL), Lesser GPL (LGPL) (unless you are merely dynamically linking a shared library), or Creative Commons Attribution-ShareAlike License. Code or content under the following licenses, for example, are allowed: BSD License, MIT License, Microsoft Public License, or Apache License. You may not sublicense Licensed Technology under a Non-Compatible License."

IMHO to dev an open source game with these license-locked engines (including Unity) is a real paradox (no pun intended).
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Re: Can commercial engines be used for open source games?

Postby Blue dragon » 27 Jul 2014, 15:46

Now you can use unreal engine 4...And if you want your game to be open source but still don't like even that engine,you are either asking too much or should develop your own engine.
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Re: Can commercial engines be used for open source games?

Postby rogerdv » 28 Jul 2014, 13:06

Sounds interesting, but I cant pay the license.
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Re: Can commercial engines be used for open source games?

Postby Julius » 28 Jul 2014, 21:26

UE4's pay as you go license model is not "open-source" anyways, but at best "shared source". Might be a great educational resource for FOSS engine developers though.
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Re: Can commercial engines be used for open source games?

Postby Taknamay » 06 Aug 2014, 18:01

I have been using Godot for a few months. It's pretty great, and the IRC/forums are very responsive. The documentation needs a lot of work, however.
Check out the #freegaming tag on fediverse.
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Re: Can commercial engines be used for open source games?

Postby rogerdv » 06 Aug 2014, 18:39

I took a look at Godot, and yes, the documentation suddenly stops leaviung you with no actual clue about how to make a game. Not to mention that the renderer is old.
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Re: Can commercial engines be used for open source games?

Postby gouessej » 08 Aug 2014, 12:38

devnewton {l Wrote}:Try http://jmonkeyengine.org/, http://www.polycode.org/ or http://www.maratis3d.com/ if you want something like unity.

Personally, I can't install the Unity player under the GNU Linux distro I use daily. Thank you for mentioning polycode and maratis3d. JMonkeyEngine 3 has a fully integrated game development environment and a large community.

Some developers here complained about the poor tooling of open source / free engines. I agree with them; things were worse in 2005 when I started 3D game development but now, there are still some missing blocks even though some of them have an excellent documentation. Some engines want to do too much things at the same time and you have to rewrite some modules to get the job done. Most of the time, you have to tinker each separate tool a bit, you don't have anything unified. Actually, I suspect that lots of engines aren't written by game programmers which leads to nice toys but without any clear workflow. In my humble opinion, providing all features through an editor isn't trivial. As Julius wrote, some WYSIWYG editors are nice for prototyping but in my humble opinion, you can't drive everything simple to express without making some simplifications in the supported game design or without making some aspects scriptable.

As I'm mainly interested in first person shooters, I can speak about this kind of game. Cells and portals are very rarely supported in free / open source engines. I'd like to spend some time in providing a nice implementation. This is my biggest concern and I already have my own tiny editor :) ( :gpl: :D ).

rogerdv, do you really need Unity 3D?
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Re: Can commercial engines be used for open source games?

Postby rogerdv » 08 Aug 2014, 14:44

What I need is some easy to learn/use engine like Unity3d. Definitely, after some months, I have decided that Torque3d doesnt meets the requirements (easy to create scenes, but almost impossible to learn, lacks documentation). It is so ugly that before using it, I hated Unity3d and now I like it.
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