Hi everyone,
Since we have been doing a lot of talking about game engines and
toolkits like BGT I thought I’d bring up one of the current projects I
have in the wings. I’d like to get some end user feedback and
suggestions on it as I plan for this to be more or less a community
driven project not only to help aspiring game developers to get
started with creating games, but also to begin cross-platform
development of games for currently unsupported operating systems like
Mac OS and Linux as well as the latest Windows releases too.
The project is named Open G3D. That basically stands for Open Genesis
3D. A purely open source and free version of the Genesis engine that
will be cross-platform as well as uses open source APIs such as SDL
for game development. That’s the basic overview.
However, before I begin releasing beta versions of the engine it would
be helpful to know what features you potential game developers would
like to see in the engine. For example, I have two different versions
of the Genesis Engine.
The first is the newer C++ version of the engine that is currently
written in pure C++ which could be ported to Mac OS and Linux via SDL,
OpenAL, and other open source libraries, but would be more difficult
to program/use since it is written in pure C++. The Disadvantage here
is that you would have to manually compile it on every single
operating system and platform you intend to support. So if you wanted
to support Mac OS  and didn’t have a Mac, for example, you couldn’t
support the Mac platform until you purchase a Mac and use the Mac
C/C++ development tools. This is, in my opinion, the principle problem
with using C or C++ for serious cross-platform development.
The other issue is at this time I haven’t added a user friendly
scripting engine to the game, such as BGT has, so at the current
moment if you don’t know C or C++ you can’t easily use the engine. I
could easily fix this by creating a self-contained core like BGT and
then use an open source script language like Lua to give the open
source game developer something easier to tackle as well as speed up
development time However, on the good side writing the Open G3D engine
in C/C++ you have full access to native libraries such as
Speech-Dispatcher on Linux, Sapi 5 for Windows, and the Mac OS Speech
API. Not to mention access to the default graphical toolkits like GTK,
Win32, or Cocoa. All are things that would probably be a good idea to
have, but not exactly cross-platform friendly.  SDL has its own GUI to
use instead so supporting individual graphical interfaces isn’t
necessary most of the time.
With C/C++ you can get better game performance, but usually at the
cost of doing your own memory management or clean up. As pointers etc
are an advanced programming technique and this is intended to be a
community project I see this cutting both ways. Good in a way but bad
for newbies in a big way.
The other version of the engine is the .Net version of the game engine
which MOTA used clear up to beta 10. It was written in C# .Net and is
more or less stable except for Managed DirectX which could be removed
and replaced with an open source API like SDL easy enough. It is
already fairly along in development and with perhaps a month or so of
work could be ported over to the open source Mono Framework and SDL
which is cross-platform. This is in my opinion probably the best
choice and solution for something like this.
For one thing since Mono is open source and is supported on Mac,
Linux, and Windows you don’t need to recompile your application to run
the game on Mac, Linux, or Windows. You create it in the Monodevelop
IDE, compile it for either 32bit or 64bit mono, and that’s it. Someone
downloads and installs your game and runs it provided they are using
the same version of Mono for their platform you are. This makes the
task of creating open source games that you build once run anywhere is
why runtime environments like this are important for software
developers. It simplifies the task a lot.
The other reason I think this is a good idea is the .Net languages
like C# are very newbie friendly and are far simpler to learn and use
than C++. You don’t really need a scripting language when using C# as
the language is pretty simple in of itself. Plus having something like
the Mono Framework it wraps the core libraries of Windows, Mac, and
Linux giving the developer a single object oriented API to work with
that is the same on all three platforms.
For example, the Mono dll, System.Windows.Forms.dll, is used to create
windows, buttons, list boxes, and so on. The nice thing about this
library is that it uses the operating systems default GUI when
actually rendering a window. On Windows XP, Vista, or 7 it would draw
a window using the Windows API. On Linux it would render that same
window using GTK. That makes the app screen reader friendly as well as
uses the default color scheme etc of the operating system. On Mac I’ve
heard they had some access problems with Mono, but as for the other
two platforms it is a simple way to render graphical games etc with
ease without having to support three different graphics toolkits
directly.
The primary disadvantage of things like C# .Net and Java is you need
to download and install a large runtime library. For those Windows
users running Windows Vista and Windows 7 don’t have to worry about
this as they come with .Net Framework 3.0 and .Net Framework 4.0 so
there aren’t any dependencies to install except for SDL .Net which is
like 5 MB or something like that. For Linux users it isn’t hard to
install as apt-get and yum can be used to download and install
dependencies, but is still a pretty big download/install. I’m not sure
about Mac, but I know from experience with .Net products before a lot
of problems come up just from people not running the latest and
greatest .Net stuff. Although, as Mono is designed independently from
Microsoft it might be a bit less of a headache as they aren’t
releasing new versions constantly.
The next topic of interest is an audio library. There are really two
to choose from here. SDL’s SDL Mixer and the OpenAL API. Both have
advantages and disadvantages from a programming aspect.
SDL Mixer is a simple mixer with basic stereo panning, sound
positioning,  and some built in support for ogg, wav, and some other
file types. It is extremely easy to use, but is also a bit limited. It
really doesn’t have much in the way of virtual 3d audio support, but
will let you position the direction of the audio by passing it an
angle of the sound and setting the volume. While primitive there isn’t
any reason a game developer couldn’t create a wrapper function that
uses some virtual 3d calculations to come up with the correct angle
and volume and pass that off to SDL more or less emulating a virtual
3d audio environment. Still it is generally not really made for really
high-end games with advanced audio environments.
That leaves us with the alternative. There is OpenAL which is
supported on Mac, Linux, and Windows. Unlike SDL it was designed for
high-end games using virtual 3d, some DSP effects, and so on. The
problem is that it is a bit harder to use and I’d definitely have to
create some kind of wrapper library to simplify it and add support for
ogg, mp3, or any other compressed file types if we wish to support
them. On the plus side though we can have 5.1 and 7.1 3d audio almost
equal to XAudio2 or DirectSound on Mac, Linux, and Windows with this
engine. Although, at the cost of a more difficult and advanced library
to use.
Another issue I would like to talk about is speech output.
Traditionally, I use prerecorded speech files to speak messages.
That’s fine as far as it goes, but I also wonder if it might not be a
good idea to try and support some sort of tts system like Sapi as
well. Sapi, Speech-Dispatcher, and so on would definitely come in
handy for RPG games and so on where there are hundreds perhaps
thousands of messages that need to be spoken. In other words in games
where prerecorded messages would be in a very real sense unrealistic
do to size or the number of messages that need to be strung together
to produce speech output. .So what do you think about TTS support?
Finally, I’ve noticed a greater demand for networked games and more
player verses player type play. The obvious choice for this would be
something like SDL’s Network API which covers the cross-platform
angle, but how many of you are really into pvp type play. I’m not so
that’s one reason I haven’t added network play to Genesis 3D, but
apparently some are and having this feature seams almost necessary for
a community driven engine. So any thoughts, suggestions, etc on this
topic is welcome.

Smile.

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