[OLPC-Games] (no subject)

[Wade Brainerd]

Hey Zach,

Just wanted to privately respond to your email- sounds like some really cool
stuff!  I have been working on getting optimized graphics running on the XO,
and have made some good progress but haven't yet had a chance to document my
results on the wiki.

I recently went through the process of taking an existing C++ SDL
application, porting it to the OLPCGames framework, and then finally to GTK.

I would probably recommend against the OLPCGames framework unless you are
doing standard "games", ie full screen and very limited UI.  OLPCGames is
based on PyGame, which is based on SDL, which is in turn based on drawing to
GTK Images, so it's much simpler and just as efficient to just work with the
GTK directly unless you really need the SDL 2D blitting functions etc.
Using GTK directly also makes it that much easier to put in UI widgets when
needed.  There is no way to get direct "framebuffer" access, e.g. map the
video memory framebuffer into your process address space, that I am yet
aware of - someone feel free to correct me if I'm wrong, and tell me how to
do it too! :)

Another note is that it's really worthwhile to build Activities around
Python if at all possible.  While it's possible to interact with the Sugar
UI from C++, it's much much harder.  My approach was to keep the low level
drawing routines, vector and matrix classes, etc in C++ and expose them to
Python using SWIG (www.swig.org).  The application logic, Sugar interaction
(journal, mesh networking, webcam interaction, UI) are all in Python/PyGTK.

Regarding rendering, the XO screen is 1200x800 16bit color (r5g6b5 format)
which is pretty high resolution for realtime work given the processor
speed.  I have had good luck with working in 1/2 res (600x400) 32bit
a8r8g8b8 color buffers, and then using an optimized upscale / format
conversion with dirty rectangle management to display the images.

Best regards,

Wade

On Jan 7, 2008 10:48 AM, zach lieberman <zach at eyebeam.org> wrote:

>
> Hi All,
>
> I just wanted to introduce myself to this group -  I am an artist /
> researcher
> based in new york.   I am currently a research fellow at a place called
> eyebeam (eyebeam.org) and we have just received several OLPC laptops, so I
> am
> starting to take a look developing content for them.
>
> to give you a background on myself, I make art projects like:
>
> tmema.org/mis
> tmema.org/messa
> thesystemis.com/drawnInstallation
> thesystemis.com/motionscapes
> www.theremediproject.com/projects/issue12/systemisgesture/
>
> and I am also part of a project called openframeworks
> (openframeworks.cc/about) which is cross platform (mac, pc, linux) c++
> library
> that wraps opengl / quicktime / freetype / rtAudio / freeImage, etc.  It's
> a
> more artistic flavored version of a toolkits like OGRE, SDL, etc, and we
> have
> a pretty good community of people making things with it.   some cool OF
> projects include:
>
> http://csugrue.com/delicateBoundaries/
> http://muonics.net/blog/index.php?postid=15
>
> Anyway, I will be taking a look at some of the issues with getting OF to
> run
> on OLPC, including perhaps alternatives to opengl (for graphics) such as
> rendering in cairo, as well as interfacing with hardware.  There are
> several
> folks here at eyebeam and in new york who are interested in this, so we
> will
> try to create a wiki page and post progress.  Out first steps might be
> very
> basic, but we have some ideas for games / experiments that would use the
> hardware capabilities of the OLPC to create playful interactions.   it
> will be
> a good challenge for OF to get it up and running on OLPC too, so I am
> excited.
>
> Anyone who is in new york is welcome to get in touch with me offlist and
> come
> through eyebeam (we've already had MIT folks come for an openframeworks
> workshop).  We will likely have OLPC days here where we can meet and
> develop
> demo apps, etc, and it would be good to meet other developers face to
> face.
>
> Take care!!
> zach
> _______________________________________________
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> http://lists.laptop.org/listinfo/games
>
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