Introducing Longford, a (partly) Gideros-compatible open source game engine

john26

(posted with permission of Gideros Staff)

Dear All

I have written a Lua-based game engine called Longford which is substantially compatible with Gideros code. I have released Longford free and open source and would encourage anyone interested to use it to port games to platforms not currently supported by Gideros. I'd also very much welcome contributions to what I hope will become a lively community project. I hope that experts on various platforms will come forward and port Longford to a range of systems and devices (maybe including obscure and retro devices like Amiga, old consoles, maybe even Commodore 64)

My intention in writing Longford was to port my games to platforms which Gideros does not support. At the moment, Longford can output native Windows apps and BlackBerry PlayBook apps (probably also works for BB10 phones, not tested). I've now got my game Nebula Retro running on my BlackBerry PlayBook. To convert from Gideros to Longford, I changed only 2% of the code. (however, you should bear in mind that I wrote Longford largely with Nebula Retro in mind so your project may need more work than this!)

Here are some of Longford's features:

+ Sprite hierarchy. Sprites drawn in order according to a display "tree". User can rearrange tree using commands like "addChild", "addChildAt", "removeChild" etc
+ ENTER_FRAME and touch events which propagate through the display tree. The "stopPropagation" command stops further propagation of touch events if necessary.
+ Creation of Sprites including polygon Shapes and rectangular Bitmaps with alpha channel (which can be imported as PNG, JPG, TIFF, BMP, TGA files)
+ Creation of textfields based on bitmap fonts. Fonts should be initially generated using Bitmap Font Generator from Angel Code. (free)
+ Translation, rotation and scaling of sprites.
+ Box2D for simple single-fixture bodies. Joints are not currently supported.
+ Box2D collision events
+ Sound system. Play sound effects using WAV files and stream music using OGG files. (note that MP3 is not supported at present)
+ Automatic "tweening" system where sprites can be transitioned smoothly between position, rotation, scaling (etc) states with a single command. The transition can be linear or non-linear (including exponential and "bounce" transitions).
+ Different scale modes on physical devices depending on device screen size. Automatic bitmap substitution "@2x" etc.

Here are some things Gideros has but Longford does not support:

- MovieClips, Meshes, render to texture
- texture filling of polygons
- custom events
- support for physical keyboards, soft keyboards, accelerometer, vibration
- Anything to do with purchasing or ads (e.g. IAP)
- Internet access
- lots of Box2D stuff needs to be added

Here are some things which are different

* Longford streams OGG rather than MP3 music files
* GTween is built in to Longford. Tweens are properties of sprites not separate objects
* When Box2d bodies collide, the body rather than the fixture is passed to the collision listener
* Does not use |R| and |D| for file access but rather getPath() and getDocsPath() functions
* OO using Core.class is supported via a separate library (class.lua) not part of the core
* Longford does not automatically import any Lua files. You need to "require" files explicitly.
* Longford can export for Windows and BlackBerry native. Does not currently support iOS or Android.
* Everything is specified in the Lua files including system-level stuff like Logical coordinates etc. There is no separate properties file and no IDE.

You can find the full manual and API reference here:
https://sites.google.com/site/simpleinteractive1/longford/longford-manual
https://sites.google.com/site/simpleinteractive1/longford/longford-api-reference

You can download Longford from SourceForge:
http://sourceforge.net/projects/longford/

Go to where it says "Longford Code". As well as the source code I've included an EXE file. Just run this and use the File menu to run some of the included examples. That's the quickest way to start.

Finally, here is a video tutorial I did


(I have prepared English subtitles which you can translate if you want).

Like all open source projects, Longford runs on encouragement. The more encouragement I get the more likely I will be to write/fix stuff! So let me know how you are getting on and what features are missing. Longford is in a beta stage at the moment so don't expect everything to work perfectly straight off. You can see from the above that there are lots of things I know I need to add, particularly for Box2D. But let me know if I've forgotten other stuff.

Please feel free to write comments on the Longford Forum on SourceForge. (link above)

And if anyone wants to get involved in the actual coding, I'd welcome that too!

Scouser

Having already had a play with Longford over the past couple of months (sort of bug testing, giving feedback etc.) I can say it performs quite well.

I am hoping to port a few things over to Playbook/BB10/Windows in the near future and will provide feedback to both the community & @john26.

OZApps

@john26, the only catch, your batch files have some hard coded paths and therefore do not compile.

Congratulations on the code, it is indeed a nice addition for BB or Windows apps.

Sidenote: You are still on XP or is that a virtual machine?

john26

@OZApps, Thanks for your kind words! Yes, my batch files will need to be changed so you can compile. I didn't want to write a complex makefile as I personally don't like automake and friends.

Yes, I'm running Windows XP, welcome to 2001! (Hopefully Longford will run on Windows 7! Please let me know).

In the near future, I'd like to add support for Mac OS X app store and maybe the Ubuntu app store.

Scouser

I can testify that Longford does indeed run on Windows 7 64 bit.

john26

Phew, good to hear it ! :-)

jdbc

I was planning to migrate some of my games to Windows Phone.

I will try Longford then to use my Gideros codebase.

john26

Unfortunately, Longford does not currently target Windows Phone 8, only Windows desktop apps. However, we could add WP8 later. If you know about WP8, maybe you could add the necessary code? Since Longford is open source, it is easy to add new targets -- and Longford is very OS neutral so easy to port. (90% of the code stays the same)

talis

First of all i really congratulate you for the hard work, especially open source part is really the most enjoyable part of it >- I just wished myself that i had time to dig into code

By the way One question:
-As far as i saw from the movie all lua files and assets are human readable. (without encryption of any kind). Is there any plan in your mind to implement encryption?

john26

Thanks Talis, you can try the program without recompiling if you like. Just download run longford.exe and try running some of the examples.

I don't have an immediate plan to implement encryption. You can, of course, byte compile the Lua files and distribute those instead of human readable Lua. Not the same thing as encryption of course but I guess it deters casual hackers...

I think in my next video I will give a run through of where everything lives in the code to help people to port to different OS's and just see where everything lives.

absinthe

Well, it's running on Windows 8 in Parallels, if that helps! I just downloaded the .exe and all the .dlls (plus I had to locate openal32.dll) into a single folder and it worked fine.

I'm not very good at this so I haven't been able to get my current project ported, but it's nice to know the option is out there to explore. Thank you!

john26

Thanks very much @absinthe, I'm glad to here it works on Win 8. Longford uses standard Win32 API calls so should run on every version of Windows. Maybe I will ship the OpenAL DLL from now on? It is certainly not as ubiquitous as OpenGL.

Did you try all the examples?

absinthe

I didn't, I'm a little embarrassed to admit that I couldn't figure out how to download the files except one at at time!

It was pretty difficult to find the Open AL dll since it doesn't seem to be available through the original host anymore, but I did find the installer on google code (user "rallyraid").

john26

SourceForge can be quite confusing! The simplest way is click on "Longford Code" then select "Download snapshot". You'll then get a zip file with all the files. (See picture)

A more advanced way is to set up Subversion and then check out the code. You can then check it out again in future and get the latest version immediately. I use TortoiseSVN which is a GUI version of Subversion.

absinthe

Huh, I could have sworn I tried that and got a weird error that made me nervous I was messing with something I shouldn't. But I tried it again and it worked!

The demos work great under Windows 8, no issues at all.

unlying

Doesn't work for me:(
Crash after choosing any project:
Problem signature:
Problem Event Name: APPCRASH
Application Name: longford.exe
Application Version: 0.0.0.0
Application Timestamp: 52f80588
Fault Module Name: StackHash_0a9e
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 00000000
Exception Code: c0000005
Exception Offset: 057b503f
OS Version: 6.1.7601.2.1.0.256.1
Locale ID: 1049
Additional Information 1: 0a9e
Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
Additional Information 3: 0a9e
Additional Information 4: 0a9e372d3b4ad19135b953a78882e789

john26

Thanks for trying it out. I did a search and this StackHash_0a9e error seems quite common on Win7 64 bit. E.g., this error report is almost exactly the same:

http://forums.steampowered.com/forums/showthread.php?t=2534355

longford.exe was compiled on Windows XP and is a 32-bit exectuable. From what I've read, it seems older (maybe 32-bit software) is crashing on some Win7 64 bit computers. Could you try recompiling Longford as a native 64 bit exe?

One person claims it is due to a "botched" automatic update from Microsoft:

https://forums.geforce.com/default/topic/549500/solution-for-stackhash_0a9e-errors-and-possibly-others-/

A large number of games are effected including 2013 Tomb Raider, Crysis 3 etc. He claims the problem is fixed by removing update KB2670838. You could try it.

Here's another link where people claim to have solved it

http://www.hitmanforum.com/index.php/topic/57471-resolved-hitman-absolution-crashes-before-launching-bex/

I will look into this some more. But recompiling seems a good option. You will eventually need to compile to release a Longford game anyway.

unlying

@john26 can you provide archive with all that stuff that should be downloaded? Because i have a problem on EVERY step with missing files. May be it is because of different versions, may be smth else, but it is too hard for me to make it works yet.
Btw, i have 32-bit win7.

john26

Hi there. I think I definitely need to make installation easier. Can we discuss over at the Longford forum?

http://sourceforge.net/p/longford/discussion/

I'm sure we will sort it out!

john26

I've now released a binary version of Longford for you to install on PC.

https://sourceforge.net/projects/longford/

Just run the installer and Longford will install in your Start Menu. Then, try running some of the examples in the "examples" folder. Select "main.lua" in most cases. Please let me know how you get on.

unlying

@john26 thanks, it works now. I can't run any my games because it looks like it doesn't support scenemanager

john26

Thanks for testing it, I'm glad it works. Yes, some things are done differently so some conversion work will be needed. Scenemanager depends on custom events which are not currently supported but which I intend to add next. To do sprite inheritance like Baddy=Core.class(Sprite) you need to require "class.lua" which you should find in one of the examples. Longford does not import any files automatically so you will need to add lots of "require" commands in Lua.

If you like I'd be happy to look at some of the code and help get it working.

john26

Have added LuaJIT!