
Liquidfun – 2D physics engine for games - iamtechaddict
https://github.com/google/liquidfun
======
de_dave

      For applications on Google Play that integrate this tool, 
      usage is tracked. This tracking is done automatically using 
      the embedded version string (b2_liquidFunVersionString),
      and helps us continue to optimize it.
    

Is this tracking functionality restricted to libraries by Google employees?
Seems like it would be useful for all third-party library developers to see
how their libraries are being used and can be improved.

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eloisant
[http://www.appbrain.com/stats/libraries/overview](http://www.appbrain.com/stats/libraries/overview)

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babuskov

        "For applications on Google Play that integrate this tool, usage is tracked."
    

Imagine if every open source library did that.

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tenfingers
Pretty sad they decided to do this, actually.

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philbarr
They're not the only ones to do this. Vuforia is worse, it's free, which is
tempting, but then Section 8 (i) of the license agreement[0] states:

"each end user consents to the collection, storage, and use by QCE and its
affiliates and service providers of Statistics from the Software and the
transfer of Statistics between QCE and its affiliates and service providers
(which may be in the United States or in other countries), in each case for
the purposes of (a) facilitating the provision of new products, updates,
enhancements and other services, (b) improving the Software, and other
products, services and technologies, and (c) providing new products, services
or technologies to You and customers of QCE and its affiliates;"

To be fair, they're giving away a great SDK for free that they've put a lot of
effort into, so they can demand what they like from the license. Google can
too - you don't _have_ to use the free stuff they're giving away.

[0]
[https://developer.vuforia.com/legal/license/2-8](https://developer.vuforia.com/legal/license/2-8)

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stuaxo
Hm, what are the data protection act implications of this ?

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philbarr
I think as long as you tell the user then you're ok. If the user wanted to
find out what information the Vuforia guys have collected they would have to
ask them, pay the £10 (in the UK), and then it would be up to the Vuforia
people.

I use to be the "Data Protection Expert" at a firm a few years ago, but really
all that happened was they sent me on a course and I read the rules. Never had
to actually deal with a case.

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a-nikolaev
They say that this is an extension of Box2D, not a really new engine. This is
kind of important, because the simulation of soft spherical particles is a
much easier problem than the simulation of rigid bodies. (Unless they are
doing some fancy things I'm not aware of). Maybe, there is some complexity in
handling both soft and rigid bodies, but I don't think that there should be a
problem.

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aaronetz
I wonder why they came up with a new library instead of contributing to box2d
directly? Unless they had to break box2d's API (but off the top of my head,
without looking at the code, it's hard to see why they would have to)

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talmand
What's wrong with creating something new?

If someone decides to attempt something but there's already a similar project,
why do so many think they should abandon their own to contribute to the other?

They can always contribute down the road.

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TheCraiggers
Creating a large software project is hard and time consuming. Lets use an
analogy to help visualize it: say, building Eiffel Towers.

If everyone collaborated on a few such projects, we'd have a few really great
Eiffel towers scattered around.

If everyone started their own, we'd have a million piles of metal all over,
and very few towers.

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talmand
I think your analogy, while a good one, is quite a bit off on scale there.

But if I wanted to attempt to build my own Eiffel Tower in my backyard, why is
it bad that I wish to do so? Maybe I just want to do it to see if I can
accomplish it?

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TheCraiggers
>I think your analogy, while a good one, is quite a bit off on scale there.

According to wiki.answers, it took 300 people just over two years to build the
Eiffel Tower.

Now compare that to Linux, or Gimp, or any other large OSS project and tell me
the scale is still off. Or were you claiming that I was off in the other
direction? In which case... I might agree with you. ;-)

> But if I wanted to attempt to build my own Eiffel Tower in my backyard, why
> is it bad that I wish to do so? Maybe I just want to do it to see if I can
> accomplish it?

It depends entirely on your motive and goal. If your goal is to build it
yourself, if your motive is just "see if I can build this with my own power"
then there is nothing at all bad. I applaud that. If your goal is to make the
best software to fill a certain gap, if it's to make the world a better place
with the highest change/effort ratio, then I would argue that adding your
knowledge & power to an already existing project is the better way.

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sgt
It's interesting how much Google is using Github. Will we see an acquisition
of Github in the near future?

~~~
scrollaway
There was a time I would have really hoped for that. When Github was still new
and the only, pathetic, alternatives were SF and Google Code. But back then,
Google had its head stuck all the way up SVN's trunk.

Now I really hope they don't acquire Github. No website I know of has improved
in such a consistently good way. Pure UI improvements, awesome new features
and no feeling of feature creep on the user side (I don't feel overwhelmed by
Github's features at all, I just want to try them all!).

Google does a decent job on their apps but I honestly think Github is a much
higher quality shop: do one thing and do it _extremely_ well.

With all that said, how much Google uses Github has little to do with
acquisitions. They also use Twitter and you won't see them acquiring that.

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seszett
> I honestly think Github is a much higher quality shop: do one thing and do
> it extremely well.

You're saying this because you haven't heard about or used atom.io ;)

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scrollaway
I've heard about it. I have an invite left in fact if anyone wants. As a linux
user though it's useless to me currently.

But atom.io is not part of Github. Sure, it's made by them, but when I talk
about Github I mean the website.

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milesokeefe
If you still have the invite I'd love it. Email's in my profile.

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zurn
I didn't spot a liquid (without particles) looking demo in the videos - would
that be easy to make? Would you be able to make visuals look like Wii's
Fluidity game using this easily?

~~~
codeka
Yes, you basically render the particles as metaballs for that sort of effect.
Should be doable in glsl, though I haven't personally done it.

Edit: here's a video showing the technique:
[http://vimeo.com/4391370](http://vimeo.com/4391370)

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timknauf
Yep, those kind of 2d metaballs are indeed doable in GLSL - I have a WebGL
proof-of-concept lying around. I really struggled to get good performance,
though my shader-fu isn't up to much.

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seanmcdirmid
Metaballs are too expensive for more than a few particles. There are probably
some other algorithms that would work better, or not doing metaballs strictly.

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asadlionpk
I found metaballs as very efficient when using pixel shader. I did port my js
fluid simulation to C++ and used cocos2dx with shaders to do it for iphone.
Works good.

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bcraven
Looks like:

\- OE-CAKE[1]

\- Phun/Algodoo[2]

Which may give some examples of what could be done with this.

[1][http://www.teq.com/blog/2010/03/oe-cake-physics-
simulator/](http://www.teq.com/blog/2010/03/oe-cake-physics-simulator/)

[2][http://www.algodoo.com/what-is-it/](http://www.algodoo.com/what-is-it/)

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sdgsdgsdg
How long before an emscipten js version?

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wingi
[https://code.google.com/p/jsbox2d/source/browse/trunk/build/](https://code.google.com/p/jsbox2d/source/browse/trunk/build/)

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woogle
Every time I see code.google.com my brain anticipates the pain and it actually
hurts. Please don't do that again. Even Google is using Github now.

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CmonDev
It's surprisingly reasonable that they did not use Python or JS for it. I
wonder how they came up with this project though - do they want to boost
Android/NaCl games?

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asadlionpk
I made one for js :
[https://github.com/asadlionpk/SPHjs](https://github.com/asadlionpk/SPHjs)

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CmonDev
It's pretty cool, but not useful for games due to performance limitations
(especially for mobile devices).

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asadlionpk
Shamelessly plugging my library for js :
[https://github.com/asadlionpk/SPHjs](https://github.com/asadlionpk/SPHjs)

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rehevkor5
The liquid seems a bit compressible, more like balls of jello or rubber than
water. Is that a difficult or costly problem to resolve when simulating
liquids?

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alexvr
Anyone see the Strandbeest in the video?

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vanderZwan
Well, it said "Theo Jansen's Walker" so it was kinda hard to miss :)

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alexvr
Oh, I found the other stuff too cool to notice any text :p

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willemmerson
The music fits surprisingly well, its Interstate by The Juice To Make It
Happen, whoever they are.

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dlsym
I somehow expected JS...

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pkrefta
I expected Dart...

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timinman
Someone make a realistic surfing game!

