New version of Sparrow + Chipmunk

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New version of Sparrow + Chipmunk

(28 posts) (11 voices)

Started 1 year ago by ronaldmathies
Latest reply from ronaldmathies

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ronaldmathies
Moderator

Hi All,

I've been working hard to get this new version ready before i go on vacation, this version is much improved with a lot of new features.

So what was it all about?

Chipmunk is a physics library which is written in C, now most people who program for the iPhone have no clue of C which makes it strange and maybe even hard to work with. Now for Chipmunk there is a commercial licensed Objective-C wrapper available but it costs nearly $200, which i find a bit disappointing, it could be well worth the money but just not for me.

Besides that it doesn't have a nice integration with Sparrow, now i don't say that this version already has it but is has some.

So what did it already support?

Basic functionality, bodies, shapes and a manager to manage it all. Also the automatic updating of SPDisplayObjects that are attached to the bodies. It wasn't much but it was a nice start.

So what does it now support?

Constraints!, all the constraints that are available through Chipmunk are now also supported though the wrapper, this includes:

Damped rotary Spring
Damped Spring
Gear Joint
Groove Joint
Pin Joint
Pivot Joint
Ratchet Joint
Rotary Joint
Rotary Limit
Simple Motor
Slide Joint

What else is new?

The collision handler has had some improvements, now you can also register a global handler, and handlers which only respond to certain phases of a collision.

There is now also support for window bounding boxes, this means you can add a border around your screen preventing objects from floating away.

But does it work?

Well, now you can see for yourself, i have included demo's for all the different constraints, just run it in the simulator and step through all the demos. You can also use the mouse (touch) the influence the objects itself, but keep in mind, the mouse can be a bit icky sometimes, don't know why but it responds very heavy sometimes, so go slow with dragging.

Everything you see on the screen is literally what Chipmunk knows, this is called debug draw. If you want to add it to your own project you can add a SPDebugDraw component to your stage which will render everything from Chipmunk.

Where can i get it?

You can get it over here: http://www.sodeso.nl/Chipmunk.zip (mind the capital C )
GitHub source: https://github.com/sodesocompany/Chipmunk-Objective-C-Wrapper
GitHub download: https://github.com/sodesocompany/Chipmunk-Objective-C-Wrapper/archives/master

How to use it:

Look at the description on this posting for more information (also check out the video made by enbr):

http://forum.sparrow-framework.org/topic/sparrow-chipmunk-demo-project
video: http://cl.ly/0B2j0O3Q2n3N0t0A2g09

So what can we still expect?

More demo's, further integration with Sparrow (where applicable), more control over property changes of bodies and shapes. And the manager class needs to be revised a bit.

This will all have to wait a bit,i am going on a holiday the day after tomorrow so i will be back in about two weeks.

Posted 1 year ago #
Shilo
Master Sparrow

This is awesome! Great work, I'll check it out as soon as possible.

Posted 1 year ago #
baike
Moderator

Awesome work, Ronald!

Posted 1 year ago #
ronaldmathies
Moderator

Thanks, with the addition of the demo's it's also much clearer to see how it all works.

Posted 1 year ago #
freerunnering
Moderator

Struggeling to get chipmunk to compile but really looking forward to trying this out, great work ronald!!!

Posted 1 year ago #
Daniel
Primary Feather

Sounds really great, Ronald!!!
BTW, have a good vacation! You've definitely earned a break, I'm sure this was a lot of hard work.

Posted 1 year ago #
ronaldmathies
Moderator

Oh, and for the information, i would not use this in any real application yet. It is still quite buggy and the memory is not optimized yet so it has some leaks.

I am working hard on getting that corrected first.

Posted 1 year ago #
ronaldmathies
Moderator
Oke, well, i uploaded a new version (couldn't resist )

http://www.sodeso.nl/Chipmunk.zip (mind the capital C )

A big change is that the CMManager is no longer a singleton, you now need to instantiate it and release it.

I also changed all the createXXX methods to addXXX methods, this should make it clearer that you actually add something to the object (manager, body) that has the add method.

So for example:
CMBody *body1 = [mManager addBodyWithMass:2.0f moment:1]; [body1 setPosition:pos1]; [body1 addToSpace]; CMShape *shape1 = [body1 addCircleWithRadius:15.0f]; [shape1 setElasticity:0.0]; [shape1 setFriction:0.7]; [shape1 addToSpace];
Here a body is created using the manager, so the manager is holder of the body. Then a shape is created using the body so that makes the body the holder of the shape.

The objects you get back are retained by their holder so you don't have to do that. You could basically ignore the return value or assign it to something. When you say:
[mManager release]
All the bodies and shapes will be released, one effect of this is, try not to mess directly with the chipmunk environment, this could screw up the manager, body, shape and constraint state.

Another few additions are:

SPPoint+Chipmunk.h category, add's a method for converting the SPPoint to a cpVect.

All shapes, constraints and the body now have a name property, you can set it to anything you like, handy for debugging.

CMManager now has two new methods:
- (CMShape*)findShapeAtPosition:(cpVect)position; - (CMShape*)findShapeAtPoint:(SPPoint*)point;
This allows you to find the shape that is located at the position of where you touched. This gives you even more control with touch events on images. (if you use a detailed enough shape like a poly shape)

the CMShape class now also has a - (CMBody*) getBody method, this allows you to retrieve the CMBody from the CMShape.

Some things that still need to be done:

You can add things, how about removing things? like removeConstraint, removeBody, removeShape etc...
More memory fine tuning
More properties
More demo's
And a lot of other things....
Posted 1 year ago #
Daniel
Primary Feather

Looks absolutely awesome!!! Now if I could only find the time to finally experiment with that stuff ...!

Posted 1 year ago #
pixelrevision
Member

Dang Ronald this setup is really solid. I just compiled it and started looking through your classes. I'm amazed how much you got done in such a short period of time here.

Posted 1 year ago #
Mik
Member

I never said thanks in this kind of threads cause i'm really too "unripe" yet for this kind of things but i'm very happy of what you're all doing about physic engines, collision detection, particle systems and other advanced tasks and i'll enjoy to test them all in my future projects!
Thanks!

Posted 1 year ago #
ronaldmathies
Moderator

I've made a few changes again to the Chipmunk Wrapper:

source: https://github.com/sodesocompany/Chipmunk-Objective-C-Wrapper
download: https://github.com/sodesocompany/Chipmunk-Objective-C-Wrapper/archives/master

* Added a new demo: SimpleCollisionDemo
* Removed the CollisionMoment from the collision event selectors.
* Added the CMArbiter class which wraps the cpArbiter.
* Changed the way the selectors for the collision events should be build up, they now
have the following definition:

(BOOL) defaultBegin:(CMArbiter)arbiter space:(CMSpace)space

* Changed the following method: -(void)addDefaultCollisionHandler:(id)target begin:(SEL)begin preSolve:(SEL)preSolve postSolve:(SEL)postSolve separate:(SEL)separate;

This method now has an extra argument:
ignoreContainmentCollisions(BOOL)ignoreContainmentCollisions;

If you do don't want to receive events about shapes colliding with the window
containment then set this argument to YES.

* Build a switch on the demo title to enable / disable the debug view.
* Moved the demo button bar to the bottom for easier navigation.
* New demo: Sparrow in combination with Chipmunk, ball demo.
* Added the group attribute to the shapes
* Set the elasticity and friction for the borders of the
addWindowContainmentWithWidth method to 0.5 and 0.1

* Updated the updateShape method, now it will check the CMBody's data to see if a
SPDisplayObject has been attached.
* New demo: Car demo, which will display a sort of car with suspension, it uses the
groove joint and the damped spring constraint.
* Checked compatibility with Sparrow 1.1
* Added optional offsets for the shapes, if a body uses multiple shapes you can set
the offset to get the shape in the correct position.
* CMManager is now CMSpace, another difference is that the CMSpace is no longer a
singleton, this makes it possible to have multiple Chipmunk environments running.
By default it will create an empty cpSpace.

So whats next:

* More demo's:

ComplexCollisionDemo
Some more Sparrow demo's

* See where we can provide more functionality for Sparrow users to have an easier
integration with Chipmunk.
* More improvements in memory management, working hard to find the leaks and see how
they can be managed. So far the idea is still that you don't need to do a lot and
that most of the work is done by the wrapper.
* Add chipmunk functions like query functions, sleeping functions, Applying Forces and Torques, Integration Functions. In chipmunk they are loose functions, i will probably add them as methods to the appropriate CM classes.

Posted 1 year ago #
Dan
Member

That's awesome Ronald!
Just one small thing I noticed - when you download it from github there's several classes you have to add to the project before it will build (I think it was CMArbiter.h and a couple of the demo classes).

Posted 1 year ago #
ronaldmathies
Moderator

Ah, my mistake, i should have added the project file again, forgot that one. I'll add it as soon as i can.

Posted 1 year ago #
kvaruni
Member

Nice work, the files that were missing were the CMArbiter.h and CMArbiter.m as well as the SimpleCollisionDemo.h and SimpleCollisionDemo.m . However, for me it seems that the app crashes every time I interact with the objects. I can take a look at all the demos and they work fine, but when I interact with one of the demos and move to the other demo the app crashes consistently.

Posted 1 year ago #
freerunnering
Moderator

Wow, that's brilliant!!
Thanks,I just tried it it out and it's great can't wait to start using it.

I do get “EXC_BAD_ACCESS” quite a lot though, normally when switching between demo's.
Also there's the 4 four files downloaded but not added into xcode. And the sparrow football demo is upside down (debug drawing goes up ball goes down).

Brilliant work though can't wait to start using chipmunk now.

EDIT: double post with above^

but when I interact with one of the demos and move to the other demo the app crashes consistently.

Yes it only seems to crash mostly only after you interact with it.

Posted 1 year ago #
ronaldmathies
Moderator

Hahaha, yeah, to explain a few:

- I do get “EXC_BAD_ACCESS” quite a lot though, normally when switching between demo's.

These i haven't noticed yet but i will watch out for them, does that happen in the simulator or when debugging / running from an iOS device using XCode?

The crashes are probably caused by bad memory management, i am still working on that. But having a combination of C and Objective-C is sometimes a bit confusing

- Also there's the 4 four files downloaded but not added into xcode.

kvaruni also mentioned this, i forgot to upload the project file, my mistake

- And the sparrow football demo is upside down (debug drawing goes up ball goes down).

Yeah, this is has a simple reason, Sparrows 0,0 coordinate is top left, while Chipmunks 0,0 coordinate is bottom left. So if something goes down on chipmunk it will go up in Sparrow.

Normally you don't notice this since you don't display them both at the same time.

Having the gravity set to 9,8*10 on the Y axis of chipmunk creates normal gravity behavior in Sparrow. If i want to make them the same i have two problems:

1. The code is strange since i have to re-calculate the position for Sparrow which could confuse people when reading the code as sample code.
2. The debugdraw would overlap the Sparrow images resulting in that you only see debug draw. I thought it was nice to see them both, but maybe since there is a switch now to enable / disable debug draw i will make them the same. so you only see Sparrow or the Debugdraw.

Posted 1 year ago #
kvaruni
Member

- These i haven't noticed yet but i will watch out for them, does that happen in the simulator or when debugging / running from an iOS device using XCode?

I have only tried it in the simulator. No idea if the crashes also occur on an actual iOS device. I can imagine though that combining C and Objective-C is no easy task to accomplish ... . I know both and I need to adjust each and every time I swap between them .

Posted 1 year ago #
enbr
Moderator

Mine was crashing when switching between demos in the simulator.

Posted 1 year ago #
freerunnering
Moderator

Tried on simulator and device.

Posted 1 year ago #
ronaldmathies
Moderator

Oke, here is an update, a number of people experienced crashed during the execution of the demo's, i've tried hard to solve them all and i think i have nailed them. A part was caused be a faulty handling of collisions and another part was probably because of memory leaks. I've been quite busy to find all memory leaks and so far i think i have found and solved them all. (for some reason i still have a few but they are not in my code but in the libLLVMContainer).

The situation created now should be sufficient for people to work with it. With the improvements that have been added now result in that you don't have to use any C++ / C in your code. You can now work completely in Objective-C.

I still have to do a write up on how to use the framework but the demo's already help a lot. The general rule for the allocation and freeing of objects is as follow:

As long as you don't need to retain it, don't retain it, the framework does this for you. So assigning is more then enough. If you release the CMSpace all objects created using the CMSpace are automatically removed.

Static bodies ( [CMSpace addStaticBody] should not be added to the space using the [CMBody addToSpace] method, if you do you will receive a warning from Chipmunk that you should not do this.

If you do retain objects make sure you release them before releasing the CMSpace (don't know if this is necessary but i would advice to do so)

If you find any problems please let me know!

The current head version has the following changes:

* Fixed CMCollisionHandler bug (resulting in a BAD_EXEC)
* Fixed all known memory leaks
* Added a new demo: TheoJansenDemo (not perfect yet)
* Added elasticity and friction to the window containment (user specified).
* Added the ability to set the distance on a pin joint
* Added a new demo: SimpleCollisionDemo
* Removed the CollisionMoment from the collision event selectors.
* Added the CMArbiter class which wraps the cpArbiter.
* Changed the way the selectors for the collision events should be build up, they now have the following definition:

(BOOL) defaultBegin:(CMArbiter)arbiter space:(CMSpace)space

Changed the following method:

-(void)addDefaultCollisionHandler:(id)target begin:(SEL)begin preSolve:(SEL)preSolve postSolve:(SEL)postSolve separate:(SEL)separate;

This method now has an extra argument: ignoreContainmentCollisions:(BOOL)ignoreContainmentCollisions;

If you do don't want to receive events about shapes colliding with the window containment then set this argument to YES.

Posted 1 year ago #
freerunnering
Moderator

Thanks, tested and now works great without any crashes!!
Thanks for all your work on this!

The situation created now should be sufficient for people to work with it.

I guess that means it's now AppStore app ready (advanced and reliable enough now)?

Posted 1 year ago #
ronaldmathies
Moderator

(after reading this back it might sound a bit philosophical)

Well, that depends, when is something AppStore ready?, if you use it and during your development you don't encounter any problems like performance degradation, memory leak, crashes etc... then yes it's AppStore ready.

In the end it is nothing more then a wrapper which tries to prevent the standard problems you might encounter using a combination of Objective-C and C++ / C. Imagine you have a lot of code written in C / C++ i can imagine that you might encounter more problems then using pure Objective-C. Fixing a bug in a single layer (wrapper) is easier then fixing a bug in many places in your code.

Is it totally error / bug proof, i can't say for sure, compare it to something like Sparrow (although Sparrow is way more mature) even Sparrow still contains bugs or problems (actually, every framework / library), but that doesn't mean it cannot be used for production.

Like i always say, try it, test it, if it works, no problem, if it doesn't work, find solutions.. In most cases, if you encounter a problem, the Wrapper is easy enough to understand to fix it or to find a work around.

If i look at the demo's i have created which basically are just simple versions of complex situations it should work. Almost all functionality of the wrapper is used within the demo's. And it doesn't matter if a demo is using a single body or five bodies or a thousand bodies, it is just more of the same.

Hope this clarifies it a bit.

Posted 1 year ago #
ronaldmathies
Moderator

Added two more demo's:

RopeDemo which demo's how to create a rope style effect visualizes best if you run it on a actual device due to the gravity changes when putting your device at an angle.

NewtonsCradleDemo which simulates the famous five balled cradle (bounce against each other).

Posted 1 year ago #
freerunnering
Moderator

Thanks (again)!!

Posted 1 year ago #
ronaldmathies
Moderator

Some new additions:

- Added a new demo: BlocksDemo
- Changed the default chipmunk step size for the demo's now it's set to 1/15th, looks more smooth.
- Added a frames per second counter (thanks Shilo)
- Changed the starting height of the CarDemo
- Disabled UIAccelerometer for NewtonsCradleDemo
- Fixed UIAccelerometer, now removed on dealloc of demo (might cause bugs or crashes)
- Added the ability to disable UIAccelerometer in demos (programmatically)

Posted 1 year ago #
WhiteGollum
Member

Ronald.

I have included your wrapper in my project and get a little bit confused why the SPImages are drawn backwards in the stage.

To fix it I have just modified the line 88 of CMSpace.m
from: [spObject setY:480-(shape->body->p.y)];
to: [spObject setY:(shape->body->p.y)];

PD: Good work, I really apreciate your effort.

Posted 1 year ago #
ronaldmathies
Moderator

@WhiteGollum, yes, that is correct. I forgot about that, i did that because of the Sparrow demo's. But since i added the switch to enable / disable the debug view it can be changed to what you have done.

I now also have it changed in the base code.

Posted 1 year ago #

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