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Part 1 of this series appeared in the August issue of Java Developer's Journal (Vol. 8, issue 8), and Part 2 appeared in the September issue (Vol. 8, issue 9).

JDJ: Microsoft has received quite a lot of good press (or propaganda, however you'd like to look at it) for their .NET product, and there has even been discussion that it will be/is suitable for games development with good DirectX bindings. Since Java is only just out of the gate (in terms of commercial games development), do you see .NET providing serious competition in this burgeoning market, or are there some (perhaps hidden?) advantages to Java that might make the difference in this case?

Jeff K: Don't confuse .NET the platform with CLR the VM, or C# the language.

.NET will not be suitable for games. Its XML-based communications protocol is by definition slow and verbose, and that's before you get into the other architectural issues. I have no fear of .NET becoming the default back-end technology for networked games - it was designed with business apps in mind, which need totally different properties.

As for C# and CLR (which, as I understand it, are heavily based on MSVM), there are a number of points. MSVM has always supported DirectX through JDirect, but it hasn't taken off as a game platform. That they are continuing this support doesn't seem like anything new to me. C#/CLR has none of the benefits of Java (it's not cross platform, being YADC (yet another dialect of C) it's not likely to appreciably improve either productivity or code correctness.

About all it does is muddy the waters around Java, which in my opinion is maybe all it's supposed to do.

Today we have cross-platform technologies emerging in Java that provide all the benefits of DirectX without sacrificing portability, productivity, or code correctness. Examples of this are the LWJGL open source library project, and the open source bindings for Java to OpenGL (JOGL), OpenAL (JOAL), and controller input (JInput).

Doug T: As Jeff mentions, this mostly affects Java from the C# side of things. One advantage Java has is time. At GDC this year, there was a session on Managed DirectX, which is effectively DirectX for C#, and you could have replaced every instance of C# with Java in the presentation. We've been solving those problems for years, so we have a head start.

Cas P: [Microsoft's] VM technology is currently inferior, but not for long. The easy integration with a direct, ultra-capable gaming API (DirectX) means that it's only a matter of time before M$ starts gaining a majority unless there's some direct competition in the same space from Sun. It's my belief that a three-pronged defense - for defense it is, as Java is the innocent blinking rabbit in Microsoft's headlights - is needed:
1.  Gang together with game technologies, embrace and flourish - OpenGL and OpenAL are Sun's only hope against DirectX, so they'd better start supporting it, encouraging it, sponsoring it, and even helping it. If Sun is seen to be behind OpenGL to the point where their own products utterly depended on it, you'd get the positive feedback loop required to ensure that both support each other and grow.
2.  Actively put major resources into the gaming space, gain the confidence of developers by being seen to do this, and start listening more keenly to suggestions and being a little more open about what's being done to address issues. I think we need a dedicated engineering, marketing, and support team for the whole issue, yet I feel that Jeff and Chris are the only Sun employees who are even trying, and they only seem to be let out of their cubicles once they've said their prayers to Solaris and flayed themselves for eight hours over a hot spreadsheet.
3.  Hardware assault - the big, big question: Is there room for a Java-based console, and if not, why not? Perhaps Sun could even fund it by running it on a Sparc chip. If there's no room for a Java-based console, then truly Java is failing as the games platform of choice because it's the best place it could possibly be from a developer's perspective.

Erik D: I think the problem with .NET is that you are specifically choosing Microsoft and Microsoft alone and, in effect, you explicitly exclude a large market potential.

There's no way .NET will become available on a PlayStation, for example. Of course, we also have no Java (yet?) on PS, so currently development will stick to C++.

Java does have a longer history than .NET and has proven itself in many more ways than .NET has, such as the obvious platform independence. If Java did spread to PS3 and XBOX, I'd say "why C# and stick with PCs if we already have Java?" if I were a development company.

Shawn K: I do see serious competition from this because MS will do whatever it can to move developers to Windows, games or otherwise. It doesn't matter if C#/.NET isn't exactly Java. They listen to their developers and changes get made. The fact that MS will make .NET work on the XBox and future XBoxes makes it all the more compelling.

Also, MS makes games. They make one C# game that's a hit and it's a done deal. Developers and publishers will look at C#, and the same dynamic I stated before. The only advantages for Java that I can see right now are:
1.  Huge existing developer base and knowledge base.
2.  Deep desire in game developers not to use MS stuff. That is a true phenomenon. Many working game developers I have talked to will try anything that is not MS tech.

I would like to point out some major disadvantages as well.
1.  Licensing issues
2.  Media APIs

JDJ: I know some of you are currently developing 3D games using Java. What was the reasoning behind your particular approach? Part 2 of this question is: Do you have any regrets? Are there any benefits to another approach that you wish you could take advantage of?

Cas P: First a quick mention about LWJGL. LWJGL is a modest library, still in development, and it aims to do very little other than to do things Java can't, like draw with OpenGL. There is a frequently misunderstood purpose to the library though. LWJGL is not an add-on library to J2SE to allow you to write OpenGL applications in Java. It was designed from the very beginning to be a portable console game library, even if it does end up being only completely theoretical. There's only one window in LWJGL, and we get a lot of requests for multiple windows. You can't even insist on a title bar and windowed mode; it's specifically meant to provide full screen-only games. We get a lot of requests to enable one to create lots of windows and have them behave as they should. But then it wouldn't run on a console, would it? We've deliberately created a platform based around what we know the hardware and underlying O/S need to be for gaming: a display, some speakers, a few input devices - nothing more.

A side effect of LWJGL is it enables us to deploy games with less licensing restrictions: I can natively compile my games for Windows, which solves a bunch of other problems I won't go into here, and the demos come out under the magic 5MB download patience threshold.

I developed LWJGL in the first place because I find the OpenGL API easy and, most important, fast. Java 3D is so far above my head I barely know where to begin. This is the problem a lot of developers have with Java 3D. If you want to learn 3D programming, Java 3D isn't the thing for you.

The other reason for LWJGL was simplicity. It's a platform; there's a specification to program to. It's a bit vague right now because we're only in alpha, but it removes a lot of uncertainty and hassle. I discovered Alien Flux ran on Linux without any trouble at all. I was more surprised than anyone. Once it's up and running, it behaves in exactly the same way as the Windows one. You wouldn't know you were running Linux underneath it because it's full screen. I have the same hope for PlayStation 3 one day. You'd never know it was written for the PC because all the developer has to use is an empty black screen, some speakers, and three input devices, not all of which will even be present.

Another reason for LWJGL is performance - speed and size. I can write absolutely optimized code for LWJGL and it runs in hardly any memory. Alien Flux would even run on a PlayStation's 32MB of RAM with a little tweaking to the graphics. There are no caveats with regard to performance; all the knowledge about performance is from OpenGL, so it's very widely understood. If you write a slow LWJGL game, it's because you've used OpenGL incorrectly, not because we've written some dicky code in the library.

And no regrets. Not for one moment do I think I could have done it easier or better with any other technology. GL4Java, Direct3D, Java 3D - they're all deeply flawed when it comes to writing portable games in Java. My only real regret is that it's unlikely that we'll ever be endorsed by Sun. Although if I may make a prediction here: LWJGL is very likely to become the driving factor in Java games development.

Jeff K: In terms of using OGL incorrectly, that may be true for relatively simple games, but I'm not sure it carries into the A-lines games of today. OGL doesn't give you scene graph management; you're going to need to write that yourself. It doesn't give you physics; again you're going to have to code that. My guess is that you've covered about half of the core graphics issues with OGL, or about 5% of that 10% I talked about earlier. For some folks that may be the perfect bar, for others it may be too low. However, all that being said, I do agree that being able to directly write to OGL is a good thing regardless of what you do on the top of it.

Erik D: I'm not married to LWJGL "till death do us part" or anything, but I do have a love affair with it because I like the low-level approach. It doesn't restrict me in any way and I believe it might become a key factor for well-performing games written in Java.

I've been playing a little with J3D, but I thought OpenGL was a lot easier to get into, and I like keeping in full control of things. Personally, I don't like the idea of J3D completely hiding details; of course, this isn't fully justified because I haven't done much with J3D, but I do strongly believe you should always be able to get as low level as necessary where games development is concerned and I've seen people struggle with J3D issues that they don't seem to be in control of.

If J3D had been built on top of an OpenGL wrapper, I'd probably have used that because it obviously addresses the problem of LWJGL, that there aren't any scene graph implementations available for it yet.

Shawn K: One point I'd like to bring to light is the scene graph versus immediate mode argument. We have to remember that Java 3D is implementing a scene graph, and Java/OGL is simply immediate mode access through Java. There are pros and cons to both and they're completely independent of Java and Java 3D. That argument has waged on for generations.

We chose J3D for several reasons.
1.  Ease of use. I never want to code immediate mode graphics if I can help it. It's like assembly for graphics. I use a high-level language and a high-level graphics system. I have also used scene graphs (from SGI to PC) outside of Java and plan to keep on doing so. Eventually the class I teach adopted RenderWare (a pseudo-scene graph API) once it was an acceptable practice.

One problem, due to the high level and ease of use, is that developers think they can make great 3D graphics projects and not know anything about 3D graphics. Sometimes the questions that are posted on the J3D list are atrocious. OGL is so low level you have to have a bit better programming skill as well as more 3D knowledge to use it. I experience this in my courses as well. The point being, when you know what you're doing, a scene graph or immediate mode are both great tools. When you don't know, a scene graph is a lot easier.
2.  Scene management. Just like some LWJGL users are finding, eventually you have to build a scene graph anyway for any scene bigger than a bread basket.
3.  Common data structures for public as well as private interchange. By this I mean, there's a thriving community of developers who code to J3D and easily trade huge code packages because they all use J3D classes and can be tested and integrated with very little modifications if written well. I'm not saying those actual packages will end up in a final production, but the integration-to-test phase is lightning fast. If all these developers were using OGL wrappers, the exchange would be close to nothing.

Look at the OpenGL community as it is. There's a lot of trading but it is all techniques and code "snippets," not loaders and behaviors or even collision systems because each OGL developer has his or her own scene graph equivalent structure on top of OGL that they will have to translate to for any techniques and code they get from the outside world.
4.  Better cross-platform than OGL alone. We used Java/J3D for a long time as a true cross-platform solution. Our students' laptops ran best under DirectX, and our classroom workstations under OpenGL. For their work it was no problem to use either install and everything worked. This is less of an issue today as the laptops have better support for OGL and the workstations for DirectX. The current Java/OGL world is still an OGL on Linux/Solaris/Windows world so J3D has a slight edge there.
5.  Legacy. It was the only way to do 3D in Java at the time we started.

SIDEBAR
The players are:

Jason R Briggs: Java Developer's Journal contributing editor and your host; games player when he has time, games developer...on occasion.
Gerardo Dada: Metrowerks' product manager for CodeWarrior Wireless Studio.
Erik Duijs: Former musician/engineer/producer with a (games) programming passion, now an IT consultant. Switched careers for the sake of better pay as well as maintaining a passion for music instead of "eating it" so to speak. Author of the Java Emulation Framework (JEF) and CottAGE.
Shawn Kendall: Developed Java and Java 3D-based game technology demos for Full Sail, Sun Microsystems, and I.M.I., and displayed at GDC and SIGGRAPH since 1999. He has five years of 3D technology teaching experience, and in 2002 founded Immediate Mode Interactive, LLC, a game technology company dedicated to the development and application of Java technology in computer games (www.imilabs.com).
Jeff Kesselman: Architect for game technologies, Advanced Software Technologies Group at Sun. He worked on the JDK performance tuning team and co-wrote Java Platform Performance: Strategies and Tactics.
Chris Melissinos: Sun's chief gaming officer and responsible for driving an industry-wide movement toward Java technology-based game development and building infrastructure programs for massively connected game play.
Caspian Rychlik-Prince: An IT consultant in the UK who for the last 10 years has specialized in client/server systems with RDBMS back ends. He has just released a new game, Alien Flux (www.puppygames.net).
Doug Twilleager: Chief architect of the Java Games Initiative at Sun Microsystems. One of the architects of Java 3D, he has also worked in the graphics research group at Sun looking at advanced rendering techniques and programmable shading.
David Yazel: VP of software development of trading systems and portfolio management systems at a leading financial investment company (by day), and by night a games developer for (and founder of) the Magicosm project (a 100% Java-based MMORPG).

About The Author
Jason R. Briggs is a Java programmer and development manager for a wireless technology company, based in Auckland, New Zealand. He is also a contributing editor of Java Developer's Journal. jasonbriggs@sys-con.com

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