Delta Engine Blog

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Your Christmas Present: Rocket Commander XNA


ArenaWars Reloaded - Coming Soon
Hey now!

Before you read on (I guess this is going to be a long post) please also check out www.exDream.com. We made some pictures from our new office and we recently announced ArenaWars Reloaded (see image on the right), a new game with a new graphic engine and many new cool features based on the original Arena Wars idea (the game play and levels will be similar, but look much better).

My little Christmas present for you is the new port of Rocket Commander to the XNA Framework. It allows you to play the popular Rocket Commander (113 000 played games already can't be wrong) on your Xbox 360 for the first time. You just need an Xbox 360 and have XNA on there. Here are the downloads, the file sizes are are little bit bigger than the original game (my comments are below):

  • Rocket Commander XNA on Windows (16 MB): Includes Setup, that will automatically install DirectX Dec 2006 and the XNA Framework if you don't have it yet!
  • Rocket Commander XNA on the Xbox 360 cannot be redistributed. You currently have to download the source code and run it in XNA Game Studio Express to even get it on your Xbox. Once you have Rocket Commander XNA deployed with help of the XNA Launcher you can start it anytime you want to without having your PC on or having to redeploy it.
  • Full Rocket Commander XNA source code (53 MB): All Content, Sound and Music files are included in this download, this is all you need to compile and run the game on Windows and Xbox 360. The music files are almost 50MB (5MB as mp3, which is not supported in XNA).
  • Rocket Commander XNA source code only (213 KB). No content files (models, textures, sounds, etc.) in here, just the .cs, .csproj, .sln and .fx files.
Update: 2007-01-03: Fixed some Bugs with the Input, PostScreenGlow and when device loses focus. Works now more stable. Also cleaned up some of the source code.

Note: Use RocketCommanderXna.sln to compile and run the game on Windows and RocketCommanderXnaXbox360.sln to compile and deploy it to your Xbox 360. For additional details please read the XNA documentation.

The game runs at a very good performance on the Xbox 360, you still got over 60 fps in HDTV 1920x1050 (1080p) with full AA enabled.

Check out some of the new screenshots. Warning, all of them are big, HDTV 1080p resolution. Actually I could not capture any images from the Xbox 360 directly, which runs at 60fps on 1920x1050 and uses fullscreen Antialiasing and using the highest settings. These screenshots are from my PC hooked up to my new 1920x1200 monitor, also nice :)

The main menu. Not much happend here.

The ingame HUD and general user experience has changed a bit. There is also a new object for the goal since creating a sphere dynamically is not that easy in XNA.

Rocket Commander is still fast and it pumps up your adrenaline even more in combination with a big monitor :)

Another screenshot from the last level. Please note that you can see more asteroids at the same time than in the original game. You can also look a lot farther and see more items from great distances.

The explosion is unchanged. It still looks the same crappy way, but the AnimationTexture class had to be reimplemented to work with XNA textures now.


Initially I thought "Hey, this is easy, let's port Rocket Commander to XNA.". The initial port attempt was pretty good, it took only 3-4 days to port the 25 000+ lines of code used in Rocket Commander. I could remove some classes and I also simplified some classes, the total number of lines got smaller (~20 000 lines), but after adding some new features and some new unit tests and some testing code for multithreading it is about 22 000 lines of code, still less than the original. XNA is definately the future, MDX was great, but it was not updated for a long time and if you start something new, go with the fresh XNA Framework!

Here are some of my experiences from the process of writing Rocket Commander XNA. Please note that some of these comments were written while I was developing and kinda sleep deprived. Beware of the harsh tone, in the end all worked out great :)
++ means this topic was great and better than MDX.
+ means it was good and nice to work with.
- means I did not like that feature or it was easier in MDX.
-- means this was really annoying and should be improved in the future.

By the way: I did Rocket Commander XNA just for fun, but it also proves how great XNA performs on the Xbox 360. Try to find any other game with this many polygons and effects running in 1080p (1920x1080) with AA enabled on the Xbox 360 ^^ It does not look as good as Gears of War or Halo 3, but it took only 1 man and a short time to develop and it still pushes up to 80-100mio polys each second to the GPU (in some early unit tests, the game runs fine with 20-30 mio polys per second most of the time, check out the model class and its unit tests for more details).

I also use the Rocket Commander XNA engine for 2 other smaller projects because I like the fact that I can test and play these games on the Xbox 360 too and having a complete engine up and running is always a great plus, even if you know how to do a game. It is just easier if you got all the basics covered.

Topic Rating Comments
Sound ++ Very easy to use, 1 short class instead of 2 complex ones I had in MDX. Once you get used to XAct you learn that it is a good tool for sound effects, at least if they don't have to be loaded dynamically. The porting process was very simple for sound effect files, they just had to be dragged to XACT and then the project had to be saved, that's it.
Music -- A lot of converting, different formats, hard to handle, a lot to test, bad documentation. The music from RC was below 5 MB, now it is over 50 MB, which just blows up the source code. Even the compressed take up 13 MB on the PC (ADPCM) and 9 MB on the Xbox 360 (XMA), both in a quality below the original. The rest of the game content (5MB compressed textures, models, effects, sound, etc.) stayed almost the same and could be reused for the most parts.
Unit Testing - Harder to use on the Xbox 360, no edit and continue support in the compact .NET framework. There are also no unit testing tools available and all you can do is to call static unit tests from the program class, which is still useful, but harder to do. I still prefer to test on windows. One great thing about the Xbox 360 is the fact that you get multimonitor debugging for free if you have a TV screen and your PC screen. Debug and step through code on your PC and see the result on the TV screen :)
Window handling ++ No extra code required, I could remove several classes and even the helper classes that are still in Rocket Commander Xna are not required for the most parts. Except for some of the game component classes and the design that is not really useful (more about that below) the Game class is really easy to use and simplifies the process to create a new game in a few minutes.
Shaders ++ Everything in XNA is shader based. The original Rocket Commander runs on fixed pipeline only hardware too, but it was a lot of work to handle 2 ways to render everything. With XNA you just have to write the shaders once and just use them. They work perfectly on the PC (Shader Model 1.1 up to 3.0) and on the Xbox 360, all fx files compiled without any problems.

Some shaders had to be adjusted to be right-handed now instead of left-handed like in MDX, but that did just take a few minutes to change and all the rest of the shader code could be reused. In the last few months of XNA development I never had once a problem with shaders in XNA, thats really great :)

IDE Features - MDX is much older and was never made popular by Microsoft. XNA is new, fresh and great, but it is missing some serious features like Animations for Models. You can implement it yourself, but why even bother with the content pipeline, do it all yourself. It will be much easier and you can extend it in any way you need in the future.

XNA development is currently also only avialable with XNA Game Studio Express, which is painful if you are a pure Visual Studio 2005 Professional developer and have lots of plugins you rely on every day (source code management, code rush, testdriven, slickedit, explorer, and many more). This will change in the future and XNA will grow up and dominate the whole world one day :)

Content -- Sorry, I just don't like the content pipeline (and I have been using it for several months now)! It is bad for dynamically loading textures or shaders or reloadindg them after changes (just not possible with compile-time generated content). On the windows platform you can still load textures and shaders the normal way, which is good, but loading .x file models is just not possible, you have to use the content pipeline. And the content pipeline sucks feature-wise, you have to implement all of stuff yourself.

This is my main problem, why should I re-implement generating tangents, shader technique indices, fixing other x file problems, etc. all by myself in a custom content processor, which is not easy to write IMO (bad docu again). By the time I did all that I would have implemented a much more flexible and vesatile custom importer like from .collada files, which are very popular these days ...

Performance + The overall performance especially when just doing some benchmarks and performance tests is absolutely perfect on both Windows and the Xbox 360. The GPU is pushed to its limits and there is no reason why you should be afraid of managed code. Windows performance is especially great, all my programs and games are completely GPU bound even in low resolutions and even when they only have one thread.

On the Xbox 360 the performance is much worse and you have to take many things into consideration, which is hard because there is again not much documentation around. For example the worst thing you can do on the Xbox 360 is to generate new data each frame, even if you just create an enumerator by executing a foreach loop, it will affect your performance. The good thing is that you have 3 cores (and 6 hardware threads) at your fingertips, which allow you to optimize performance. It was possible for the Rocket Commander game to optimize the game loop a lot because the physics and update threads eat up almost 50% of the CPU time. On the PC it does not matter much because my GPU is slowing everything down (see image below), but on the Xbox 360 I was able to almost double the framerate using multiple threads, nice :)


Click Image for to maximize it.

Usability - It gets a little easier though all the game helper classes, but the game component class is pretty useless, you can implement something like that in 5 minutes yourself. There is also a DrawableGameComponent class, but you have to call Draw yourself, whats the point here? My classes have some Draw or Render method anyway, I don't need to derive them from GameComponent, I can implement my own interfaces and implement exactly the features I need. Often it is easier to give the Render method a few parameters or even call it several times with different parameters, all that is not possible with DrawableGameComponent.

Next there is the content pipeline, which is just a pain in the ass for 3d models. This makes the usability very bad, especially if you develop on Visual Studio 2005 (not Express), which does not support the content pipeline. Also if you are a Vista-Developer XNA Game Studio Express will also not run as expected and my intern hates now both Vista and XNA. It should not happen that someone can get so angry about such great pieces of software, just because they don't work together ^^

Porting + If you have written a XNA game or have some XNA code flying around (like the Rocket Commander XNA source code) it is very easy to port existing MDX code to XNA. If you do it from the scratch it is a lot more work and testing until everything works out the way you expect it, but overall it is easy to port from MDX to XNA. Thats very cool, thank the main MDX man Tom Miller for that, who architected parts of XNA too. Porting is easy, but getting the game to work the way you want on the Xbox 360 is not that easy. First of all you got that annoying content pipeline again (I keep repeating myself, maybe I'm too angry ^^), then you have to make sure that you don't render important User Interface on the none-visible area of a monitor that is plugged into a Xbox 360. For example Rocket Commander was only designed for 1 resolution to look good, it had a very small font for some texts on the screen, which is unreadable on TV monitors. Rocket Commander did also not scale well on Widescreen monitors and it rendered a lot of UI elements at the screen borders, which were cut off on TV monitors.

The porting took maybe 3-4 days, but I spend at least 4 more days for fixing UI elments and improving the code on the Xbox 360, optimizing asteroid rendering, physics and multithreading. I did not expect that it would take that long and I had only some time in the evenings to even get some XNA work done.

Most annoying Porting left-handed models, matrices and other complicated math functions over to the right handed system that XNA uses. Maybe it would be easier to use left handed matrices like in the original Rocket Commander for XNA too, but XNA does not provide them and I did think getting it to work with a right handed system would be easier. Then there is of course the problem getting the models into the content pipeline. I used a special content processor, which is also included in the Rocket Commander source code and it can be used for other projects too (I use it for everything I do with XNA).

Another annoying thing is the re-deploying of existing game content to the Xbox 360. If you just have 5 files it will not matter to you, but if you got over 50 (Rocket Commander) or even several hundert content files and sometimes due some crazy bug all these files get re-compiled or re-deployed over and over again, it gets really annoying. It takes 30-60 seconds and is not fun ... good think it does not happen that often, but it is still annoying me. Maybe the main reason for regenerating the content on my PC is the fact that I often switch between the Xbox 360 and Windows platforms to test if everything is working the same way on both systems.

Missing features The XNA version does have all the features from the original Rocket Commander game, including all levels, sub menus and the whole game play. It does not have animated models however because it is not supported out of the box in XNA and I did not have time to reimplement this feature. It does also not support polygon based collision checking for asteroids, which can sometimes be annoying if you fly near asteroids or if you want to fly through the donut asteroid. The problem here is that the mesh intersection methods are missing, all you can do is render models, not much else. Last but not least XNA does not support any network code. On the windows platform it would be possible to still use the Webservice to upload and get highscores, but for compatibility with the Xbox 360 the code is currently commented out. If you want to play with online highscores, just play the original Rocket Commander game.

There are also some smaller issues like getting the bitmap data of a texture on the Xbox 360. There is method called GetData in the texture class, but it is not supported on the Xbox 360. There is also no bitmap class in XNA because you would need the System.Windows.Forms namespace, which is not included in the .NET compact framework. I ended up saving the level data into a custom file (.level) and then loading it again with help of standard IO methods (byte by byte, but the loading process is still fast, less than 1 second for all textures, levels, models and sounds).

The Rocket Commander Mods are also not supported yet, but porting them should be easy with the existing Rocket Commander XNA source code.

Improvements The controls, especially for the Xbox 360 Controller have been improved. It is now much easier to fly the rocket, the speed was increased and you can look at up to 4 times as much asteroids thanks to several optimizations and the great performance gain of using multiple threads on the Xbox 360. There are also many smaller improvements to the UI, the structure and some classes in the game, but the game looks still very similar (see screenshots above).

Maybe I will write a little more next week. I should get some sleep now, in a few hours it is christmas time and I have not packed any presents yet.

Now have fun with Rocket Commander XNA and have a nice christmas of course ;-)

PS: I know my blog has currently some problems (posting and comments do not work as they should), I will fix that in a week or two, have currently not much time to investigate this issue.