Heya people,

I just heard that the Paradox engine (http://paradox3d.net/) has gone open source, and was wondering if anyone has had much experience using it?

Cheers!

I've had a brief look at it now.

Seems like the editor that Paradox comes with is more of an advanced asset manager than anything else. It lets you import assets in to a project and manipulate their properties. You can create packages, which can contain a combination of code and assets.

Most of the work seems to be done in code though (C#), there doesn't appear to be any kind of scene editor available.

It integrates really well with Visual Studio - all of the asset packages are .vcproj files, so you can open & build the entire game (assets included) from within Visual Studio.

The engine comes packed with a whole bunch of shaders, and it looks like it supports deferred rendering.

The engine API is reminiscent of XNA/Monogame, so anyone that's used either of those frameworks shouldn't have any trouble getting used to Paradox.

I'm really quite excited about digging a bit deeper. It seems like it would be very straight forward to build up a set of common assets/code that could be used across multiple projects, and I really like that it's so code oriented (doesn't feel like cheating )

Looks like the engine is perfect for developing procedural levels, but not if you want to place anything by hand. There is a post in their answers section that suggests a scene editor is coming, but there isn't a timeline.

It seems kinda... iffy.

On one side you got the GPL3 source release, which you can use as you want since its GPL3 (while having to release the sources and blablabla).

On the other hand you got the binary release, which is basically licencing the engine from Paradox. I doubt anyone will contribute to the project if they're selling engine licences "on the side".

ie, they got all the benefits from it. If a random contributor implements a new feature or fixes a bug, they have to release the sources, and they can sell those new features or bug fixes in their proprietary licencing package.

You could argue that the benefit for the random contributor is "Hey, I'm letting you use all this stuff for free!" but eh, that would be fair only if you're also making money of the engine via selling your games based on it.

Although for 1.x they're not charging any licensing fees for the binary release (obviously that could change with 2.x). They're not asking for any royalties either.

It seems kinda... iffy.

On one side you got the GPL3 source release, which you can use as you want since its GPL3 (while having to release the sources and blablabla).

On the other hand you got the binary release, which is basically licencing the engine from Paradox. I doubt anyone will contribute to the project if they're selling engine licences "on the side".

ie, they got all the benefits from it. If a random contributor implements a new feature or fixes a bug, they have to release the sources, and they can sell those new features or bug fixes in their proprietary licencing package.

You could argue that the benefit for the random contributor is "Hey, I'm letting you use all this stuff for free!" but eh, that would be fair only if you're also making money of the engine via selling your games based on it.

I don't think this is true. If you contribute a feature, you release your code as gpl as well, which means if they want to use it, they have to Gpl everything it touches, which means they can't use it in their binary-only release.

which means they can't use it in their binary-only release.

Why not? What prevents them just grabbing the most recent code in the public repo and sell it on the side?

It seems kinda... iffy.

On one side you got the GPL3 source release, which you can use as you want since its GPL3 (while having to release the sources and blablabla).

On the other hand you got the binary release, which is basically licencing the engine from Paradox. I doubt anyone will contribute to the project if they're selling engine licences "on the side".

ie, they got all the benefits from it. If a random contributor implements a new feature or fixes a bug, they have to release the sources, and they can sell those new features or bug fixes in their proprietary licencing package.

You could argue that the benefit for the random contributor is "Hey, I'm letting you use all this stuff for free!" but eh, that would be fair only if you're also making money of the engine via selling your games based on it.

I don't think this is true. If you contribute a feature, you release your code as gpl as well, which means if they want to use it, they have to Gpl everything it touches, which means they can't use it in their binary-only release.

Why not? What prevents them just grabbing the most recent code in the public repo and sell it on the side?

Well, IANAL but it says on the website:

We gladly accept external contributions. Feel free to submit us pull requests and we will consider them for inclusion.

Contributors will need to sign electronically a Contributor License Agreement, available here (based on Harmony). It allows us to use your changes in the commercial version, and relicense code easily (in case we decide to go MIT at some point for example).

Which basically translates to "we will include your contributions if and only if you give us the rights to distribute them in the commercial version (binary release)".

The other option is to fork the GPLv3 codebase and include your changes there, where you will presumably retain the rights to your contributions, and Paradox cannot add them to their own binary release without your consent, though I believe they can legally pull them into their own repository without your permission, but it seems unlikely that will ever happen unless they want features from the open source repository to be missing in the commercial version (clearly unacceptable). And of course you must publish the source code if you release your game using anything other than the binary release.

At least that is how I interpret it having read through their blog entry. I could be completely wrong, maybe someone else knows for sure?

I've been rebuilding my sharpdx based (mixed 2d/3d) rogue-like using Paradox, and I'm really impressed with the possibilities. While I was basically building my own engine code before, it was becoming a huge effort, I made my own model format and 3ds max exporter (not all that hard) but thinking about animation and all the rest, it was becoming difficult to move forward. And i was also writing my own continuous time / swept volume collision system and physics engine, that probably will never be production ready. It's just too much work for me alone. When I actually want to be working on my game.

So when I read that Paradox uses SharpDX at it's core, and is also cross-platform and is also a pure C# engine, and code oriented, and has asset management. Well I was pretty intrigued to say the least. I've looked at Unity, and it just didn't capture my interest. While Unreal Engine 4 looked completely amazing, C++ is too daunting, and I think UE is oriented more towards teams and experts rather than a single developer like myself. It feels more natural to work fully in C#, and have a totally code oriented approach.

So Paradox is the first engine i have actually worked with. And for me, coming from XNA -> SlimDX -> SharpDX, Paradox is about as good as it gets with respect to providing a familiar environment, and yet still providing a high-level game engine, complete with a component entity system, asset management, plugin rendering systems, physics etc. I have only scratched the surface, but I'm very impressed, and I suspect Paradox will be my de facto framework from now now.

There is nothing iffy about having dual GPL and commercial licencing, this is a valid way that companies can make software available as Open Source, whilst still making money.

Yes it means that outside people are less likely to be making contributions, but if something is being developed by a group/company, I doubt they care.

"ie, they got all the benefits from it. If a random contributor implements a new feature or fixes a bug, they have to release the sources, and they can sell those new features or bug fixes in their proprietary licencing package."

As pointed out, they can't do that. If you choose the GPL licence, you are only required to distribute your code and any fixes to their code under the GPL. Which means that they _can't_ take that fix, and put it under a closed source licence.

"Why not? What prevents them just grabbing the most recent code in the public repo and sell it on the side?"

Anyone can sell GPL code, but they have to release the sources, so it would be no good for their closed source licence.

If you mean that anyone can grab the most recent code in the public repo and use it in closed source - well yes, but (a) that would be copyright infringement and (b) that argument applies to anything GPL, whether someone sells additional closed source licences or not.

This is the entire point of copyright assignment like how the FSF requires for GNU projects. You can, of course, fork a dual-licensed-with-GPL project and avoid the copyright assignment, but you'll never end up in the presumably much more popular mainline for the project. Forking is generally considered a hostile move. In some cases, it's done because the originators were dicks (see: GNU Emacs vs. XEmacs). In other cases, the forkers were the dicks (see: FreeBSD vs. DragonFly BSD).