New version of Sparrow + Chipmunk 2

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New version of Sparrow + Chipmunk 2

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Started 1 year ago by ronaldmathies
Latest reply from appwerkz

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ronaldmathies
Moderator

I've made some big changes in the area of memory management, it has been improved a lot now. Previously you could still end up with memory leaks when you removed single objects like bodies, shapes and constraints. This has now been improved a lot and a new demo has been added to also check this situation.

Also a number of query methods have been added.

To see all the changes that have been made so far please check out the following page:

https://github.com/sodesocompany/Chipmunk-Objective-C-Wrapper

To download the latest head version:

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

Here is the complete list of changes:

- Added the folowing definitions to CMTypes.h

#define CP_GROUP_TYPE id
#define CP_COLLISION_TYPE_TYPE id
#define CP_DATA_POINTER_TYPE id

These types change the cpLayers, cpGroup and cpCollisionType. The cpLayers, cpGroup and cpCollisionType are now
by default defined as being an id (keyword), this has the advantage that you can specify an NSString or
any object for that matter as a identification.

This has one side effect, you can't include the chipmunk.h header file yourself, this is not handled by
the ChipmunkManager.h file (the CMTypes.h file needs to be before the chipmunk.h header file otherwise
this won't work).

- Modified demos where applicable because of the collision change.
- CMSpace: Changed the method:

(CMShape*)findShapeAtPoint:(SPPoint*)position; renamed to: (CMShape*)queryFirstByPoint:(SPPoint*)point;

- CMSpace: Changed the method:

(CMShape*)findShapeAtPosition:(cpVect)position; renamed to: (CMShape*)queryFirstByVect:(SPPoint*)point;

- CMSpace: Added the method: - (void)removeBody:(CMBody*)body
- CMSpace: Added the method: - (CMShape*)queryFirstByPoint:(SPPoint*)point layers:(cpLayers)layers group:(cpGroup)group;
- CMSpace: Added the method: - (CMShape*)queryFirstByVect:(cpVect*)point layers:(cpLayers)layers group:(cpGroup)group;

Both do the same but take a different first parameter. These functions return the first shape that is found
at the specified point. The layers and group information is used to identify more specific which shape you are looking for.

- CMConstraint: Removed the method: - (cpConstraint*) construct; (use [constraint cpConstraint] instead)
- CMConstraint: Removed the method: - (void) free;

- CMShape: Removed the method: - (cpShape*) construct; (use [shape cpShape] instead)
- CMShape: Added the method: - (void) removeFromSpace;

- CMBody: Removed the method: - (cpBody*) construct; (use [body cpBody] instead)
- CMBody: Removed the method: - (void)free;
- CMBody: Added the method: - (void) removeFromSpace;
- CMBody: Added the method: - (void)removeShape:(CMShape*)shape
- CMBody: Added the method: - (void)setLayer:(cpLayers)layer;
- Changed collision handling: the types (A & B) are now defined as cpCollisionType

Posted 1 year ago #
WhiteGollum
Member

Hey Ronald, I'm actively following your work in the chipmunk wrapper

Thanks a lot for your effort.

I am playing with Chipmunk/Sparrow and I am a little lost (sorry I am new in this world of codding)

How can I get the speed of a Body?

I am trying to get a slow down effect in the space.

I think it should be something like this:

- (void)step:(SPEnterFrameEvent *)event
{
CMData *cmData = [mBody getData];

cpVect *vel = mBody->v;
[mBody setVelocity:(cpvsub(vel,brake)];
}

But, I actually dont know how to get the speed of the body and how to calculate the brake force.

any suggestion?

Posted 1 year ago #
WhiteGollum
Member

Well, thinking about it, I have a partial soltion for my problem.
dumping

[mSpace setDamping:0.8f];

This will make all bodys to lose 20% of his velocity per second.

But, what if I need to apply this break only for the velocity of the body that is not directed to the fron of the object?
I mean, if a body is mooving with a certain front speed and with a lateral speed, the lateral speed will be decremented each second, and the front speed will be maintained.

My goal is to simulate a boat, that will expose resistance to the lateral movement, but will continue the front movement indefinetly.

Any suggestions?

Posted 1 year ago #
ronaldmathies
Moderator

Here is a new follow up on the progress of the Chipmunk-Wrapper.

Some really nice additions have been made:

- Added the CMLoader class

The CMLoader class allows you define bodies, shapes and constraint in a .plist file, this save's a lot of space in your code and makes re-use of objects even better.

You don't have to create a single large .plist file containing everything but you can define them per object on the screen, like a space ship or a planet or a fish.

In the project is a demo file called Demo.plist which will demonstrate a number of figures and some shapes and a constraint. It is very simple to use.

The documentation will explain how the file is made up and what can be configured.

- Added appledoc documentation

This is an addition i am proud of, in enlightenment of Daniel i also used the Appledoc to generate documentation. You can find the documentation as a .docset file in the Documents folder. There you can double click on it to see all the available documentation. As far as i know everything is documented.

For the CMLoader you can also find all the information on how the .plist should be defined for all the various shapes, constraints and the body.

I have no possibility at the moment to put it online so it can be incorporated but this is already a major jump ahead.

- General: Added a lot of documentation again

- CMSpace: Added the method: - (CMBody*)findBody:(NSString*)name;

Using this method you can find bodies by their names. This is also used by the CMLoader to locate bodies. So it is imperative that
you name bodies uniquely. When you have loaded an object using the CMLoader you can retrieve the bodies using this method.

- CMPolyShape: Added the method: - (id) initWithBody:(CMBody *)cmBody vertices:(NSArray*)vertices

Another new method for defining a polygon shape. The values within the NSArray should follow the following notation:

{x,y} (including the brackets)

- CMBody: Added the method: - (void) setPositionUsingPoint:(SPPoint*)coordinate
- CMBody: Added the method: - (CMPolyShape*) addPolyWithPoints:(NSArray*)points;
- CMBody: Changed the method:

(void) setPosition:(cpVect)coordinate; renamed to: - (void) setPositionUsingVect:(cpVect)coordinate;

- CMBody: Changed the methods:

- (CMRectShape*) addRectWithWidth:.... renamed to: - (CMRectShape*) addRectangleWithWidth:....

To download the complete source / documentation head over to the following page:

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

To see all the other changes that have been made in the last couple of weeks or to browse the complete source online go to:

https://github.com/sodesocompany/Chipmunk-Objective-C-Wrapper

Additional information:

I am by no means an expert on Chipmunk, so sometimes people have questions that i probably don't know the answer to. It is my advice to go to the Chipmunk forum to ask the questions there, the author of chipmunk is often very responsive and otherwise the other members are very responsive.

I do want to prevent to clutter this forum with questions about Chipmunk since this is the Sparrow forum.

Posted 1 year ago #
ronaldmathies
Moderator

Here is another new follow up on the progress of the chipmunk wrapper:

- Added: CMExplosionEffect

This is really cool, using the CMExplosionEffect you can simulate an ... explotion..
It is very easy to use, you only need to specify where, how big, what radius and optionally a
layer and a group:

[CMExplosionEffect perform:mSpace position:[spPoint toCpVect] radius:150 force:800];

See the demo for some cool effects, hope to create more of these effects.

- Changed CMArbiter: added the method: - (NSArray*)contactPoints;

This will return all the contact points (an array of CMContactPoint objects) at the moment of colission.

- Changed CMTypes:

#define CP_GROUP_TYPE unsigned int
#define CP_LAYERS_TYPE unsigned int

It is better to have them as an unsigned int since it is more powerfull then.
Check out the documentation over at:

http://files.slembcke.net/chipmunk/release/ChipmunkLatest-Docs/
And then especially the section "Filtering Collisions".

- Renamed CMLoader to CMDefaultLoader

Makes it clear that this is the default loader variant that is directly supported
and doesn't receive sudden changes.

- Renamed LoaderDemo to DefaultLoaderDemo

- CMArbiter: Added the method: - (NSArray*)contactPoints;

Returns all the contact points that occured during this collision.

- Added the CMPhysicsEditorLoader

Just like the CMLoader this is also a loader. The difference is that this loader can load files that have
been created using the PhysicsEditor (http://www.physicseditor.de/). This product is still in beta and
support for it is not yet completed but i am working with the author to get it all working. (.plist files
will still change). So don't use it yet.

- Added the CMLoaderListenerProtocol

This is a callback mechanism for when objects have been loaded from .plist files. All methods are optional
and you can choose which callbacks you want to recieve. There are two different methods per type (body, shape, constraint).
One method is called before the object is added to the space and the other for when the object has been added to the space.

This can be used for example to attach Sparrow objects to a body so that the position and angle will be updated when
using the step function of chipmunk.

- CMShape: added the - (void)setSensor:(BOOL)isSensor; method to mark a shape as being a sensor.
- CMLoader: added the ability the load polygons from a .plist file.
- Added a new demo: PhysicsEditorDemo (not stable, still working on this with the author of PhysicsEditor)
- Added a new demo: LoaderDemo

Posted 1 year ago #
Daniel
Primary Feather

Your pace of work is really impressive, Ronald! Good work!!

Posted 1 year ago #
andreas.loew
Member
@daniel Hi

Short hello from my side... about the PhysicsEditor.

I started developing it in parallel with TexturePacker and now started to release it. It's grown from my own needs and with the chipmunk integration it'll be a great enhancement for sparrow.

Some notes about what it does:
- Support for box2d and chipmunk
- Automated tracing of shape contours
- Export to any text file format by template based exporters
- Complete management of convex/concav polygons - no need to care about that anymore
Cheers
Andreas
Posted 1 year ago #
WhiteGollum
Member

Wow, I think you read my mind, I was digging in SpaceManager (http://code.google.com/p/chipmunk-spacemanager/) and its Linear explosions features.

Downloading to test it.

Good Work

PD: I'm also a user of TexturePacker. it worth the price.

Posted 1 year ago #
ronaldmathies
Moderator

@WhiteGollum

The original explosion sample code came from space manager, i did clean up the code a bit and made it fit more into my situation but all credit goes to them.

And to have everything correct, i did check their license if it was allowed. I added their license inside the header of the code (for that particular class) And that should cover it according to their license.

Posted 1 year ago #
Mik
Member

Ronald, thanks to you i'm going to use Chipmunk in my next project, thank you very much for your work!!! Really! And the Andrea's PhisicEditor comes with a perfect timing and seems to be very good!

I would like to know if i will be able to reproduce this effect in Chipmunk: http://www.youtube.com/watch?v=imzZnae4OHg ...the buoyancy.

I read around that is not implemented in Chipmunk and that it's actually just a box2D feature, in your opinion could be difficult to achieve it in Chipmunk? It doesnt appear so difficult but there are a lot of unanswered discussion on this topic...

Posted 1 year ago #
ronaldmathies
Moderator

I think there are two things you can look at, Box2D has a sample (which is of course based on Box2D) in the contributions folder: b2BuoyancyController

Another would be to download the following:

http://maximile.net/stuff/Chipmunk-release-candidate.zip

It is a bit older but it does contain a sample of what you are looking for (Demo8.c) But i'm not sure if it will still work.

Posted 1 year ago #
Mik
Member

Thanks! I will give it a look asap.

Posted 1 year ago #
ronaldmathies
Moderator
@mik

I'm making changes to the code to make the implementation a bit simpler:

- CMBody: Added method:
- (void) setVelocityFunction:(id)target selector:(SEL)selector;
The selector should have the following signature:
- (void)velocityFunction:(CMBody*)cmBody dt:(float)dt;
- CMBody: Added method:
- (void) setPositionFunction:(id)target selector:(SEL)selector;
The selector should have the following signature:
- (void)positionFunction:(CMBody*)cmBody gravity:(cpVect):gravity damping:(float)damping dt:(float)dt;
So that solves already the method of adding a function to the body.

I will check this in later this day and i hope i can find some time to also look at how to implement the buoyancy.
Posted 1 year ago #
freerunnering
Moderator

Wow, super fast development!!

Thanks for all your work on this. Also I'd echo Mik that thanks to you I'll be using Chipmunk in my next project.
Really looking forward to PhysicsEditor, and the support for it in this.

Posted 1 year ago #

ronaldmathies
Moderator

@Mik

I added the methods.. i am still figuring out how the buoyancy works and so far i got the following demo which doesn't really work:

The code on the internet wasn't complete so i modified a few parts but it still doesn't work.

 
- (BOOL)disableAccelerometer {
	return YES;
}
 
- (void) initializeChipmunkObjects {
	[mSpace setGravity:cpv(0, -9.8*10)];
 
	CMBody *body = [mSpace addBodyWithMass:1 moment:0];
	[body setPositionUsingVect:cpv(160, 240)];
	[body addToSpace];
 
	CMRectShape *shape = [body addRectangleWithWidth:64 height:64];
	[shape setElasticity:0.0];
	[shape setFriction:0.7];
	[shape addToSpace];
 
	[body setVelocityFunction:self selector:@selector(velocityFunction:gravity:damping:dt:)];
}
 
- (void)velocityFunction:(CMBody*)cmBody gravity:(cpVect)gravity damping:(float)damping dt:(float)dt {
	cpBody *body = [cmBody cpBody];
 
	cpBodyResetForces(body);
 
	int numx = 20;
	int numy = 4;
 
	float stepx = (float)WIDTH/(float)numx;
	float stepy = (float)HEIGHT/(float)numy;
 
	for(int x=0; x<numx; x++){
		for(int y=0; y<numy; y++){
			cpVect p_sample = cpv((x + 0.5)*stepx - WIDTH/2, (y + 0.5)*stepy - HEIGHT/2);
			cpVect p = cpBodyLocal2World(body, p_sample);
			cpVect r = cpvsub(p, body->p);
 
			if(p.y > 0) {
				cpVect v = cpvadd(body->v, cpvmult(cpvperp(r), body->w));
				cpVect f_damp = cpvmult(v, -0.0003*cpvlength(v));
				cpVect f = cpvadd(cpv(0, 2.0), f_damp);
 
				[cmBody applyForce:f offset:r];
			}
		}
	}
 
	cpBodyUpdateVelocity(body, gravity, damping, dt);
}

Posted 1 year ago #

ronaldmathies
Moderator

Oke, the example works. There is only one slight problem which was also mentioned by the author of the original piece, as soon as you start to bind a joint to it for dragging the behavior could be kind of strange.. otherwise it just works fine.

I checked in all the code and the new example so you can try it out.

Posted 1 year ago #
Mik
Member

Ronald, thanks thanks thanks!!! Many times you and someone else leave me speechless for your skills and generosity and i feel very lucky to be here! I'm going to try the code today, i'm a big fan of physic in video games so, tnx again!

Edit: just seen the buoyancy demo you made, it's perfect!!!

Posted 1 year ago #
ronaldmathies
Moderator

No problem, just keep in mind that creating a pulling force like in the demo could result in unexpected behavior, you can see what i mean if you look at the demo and drag the object around in the top part of the screen. If you jist change the x/y of the body then there should be no problem. I think the problem is caused by the velocity, the velocity function sets the velocity but the constraint for pulling the object also does this.

Posted 1 year ago #
Mik
Member

I'm actually trying to code my first enviroment so i'll be able to post some eventually problem not before some hours/day of coding

Do you think would be possible to also import some file format as this one: http://www.mapeditor.org/

Before finding Sparrow i made some experiment with it and it's a real time saver if you need to build physic levels... i'm sending a PM to you with the objective-c source code of that experiment, maybe it's already possible and i dont know.

Edit: i'm playing with your bouyancy code and it's too fun! My object will not be dragged, only moved programatically so no problem at all

Posted 1 year ago #
ronaldmathies
Moderator

Here is another update on the wrapper:

The PhysicsEditor can now export correct defined polygon shapes, even when they are
concave / convex. This is a major improvement. There are still some changes that need
to be made like setting the momentum on bodies and the friction, elasticity on the shapes
but it's getting there.

- Added a new demo: BuoyancyDemo

Demonstrates the buoyancy of water, it is however somewhat limited that when
you add a constraint the effects might be strange (for example when you
drag the block arround in the upper part of the screen).

Without any constraints the blocks behave normal and it all works fine.

- CMBody added the method: - (void) updateVelocity:(cpVect)gravity damping:(float)damping dt:(float)dt;
- CMBody added the method: - (void) updatePosition:(float)dt;

- Modified the PhysicsEditorDemo to include a nicer polygon demo.

Due to valantines day i couln't resist and join the whole thing with a nicer demo,
so the demo now includes a heart shaped polygon model.

- Added CMInvocationUtils class

Simple class which creates a NSInvocation based on a given target and selector.

- CMBody added the method:

- (void) setVelocityFunction:(id)target selector:(SEL)selector;

The selector has the following signature:

- (void)velocityFunction:(CMBody*)cmBody gravity:(cpVect)gravity damping:(float)damping dt:(float)dt;

- CMBody added the method:

- (void) setVelocityFunction:(id)target selector:(SEL)selector;

The selector has the following signature:

- (void)positionFunction:(CMBody*)cmBody dt:(float)dt;

Posted 1 year ago #
Mik
Member

Sorry, this is probably a stupid question but i don't see the ball image in the ballDemo. I can see only the physic body above the ball image as in this screenshot: http://www.justcode.it/public/ballDemo.png

I'm wondering how to apply an image as a texture to a physic body.

Posted 1 year ago #
ronaldmathies
Moderator

Click on the name of the demo in the bottom, this will disable the debug view

Posted 1 year ago #
Mik
Member

yes, was just this^^' Tnx!

Posted 1 year ago #
Mik
Member

Sorry Ronald, about the PM i sent you dont waste your time answering! I just understood that my question was not Sparrow related and neither Chipmunk related. It also use an external api very long to port so... tnx anyway! I will find another way to manage my physic levels

Posted 1 year ago #
ronaldmathies
Moderator

And another update with a lot of new cool stuff:

16 Februari 2010:
- Added a new demo LayerCollisionDemo

This demo shows you how to use layers in combination with collision. This enables you to define
what can collide with what, and what cannot collide with what.

- Added the CMSprite class which is a sub-class of SPSprite, it allows you to do direct loading of a CMObject using
parameters.. HIGHLY EXPERIMENTAL and could be removed in the future.

- Added a new demo: PlanetDemo

Really cool demo which displays two planets and a object that flies by it will be attracted to
the planets as if the planets have gravity.

- Added a new demo: ImplosionEffectDemo

Just like the ExplosionEffectDemo but then an implosion.

- CMSpace: Added the methods: - (void)forEachShape:(id)target selector:(SEL)selector boundingBox:(cpBB)boundingBox data:(id)data;

The signature for the selector should look like:

- (void)doSomethingWithShape:(cpBB*)boundingBox cmShape:(CMShape*)cmShape data:(id)data;

Alows you to loop through all the shapes that are available within the specified bounding box using the specified selector.

- CMShape: Added the methods:

- (float)elasticity;
- (float)friction;
- (cpCollisionType)collisionType;
- (cpGroup)group;
- (cpLayers)layer;
- (BOOL)sensor;
- (cpBB)boundingBox;

These are just the basic getters we missed.

- CMBody: Added the methods:

- (float)mass;
- (float)moment;
- (cpVect)velocity;
- (cpVect)force;
- (cpVect)position;
- (float) angle;
- (float)angularVelocity;
- (float)torque;

These are just the basic getters we missed.

- CMShape: Renamed the method: - (id)getData; to: - (id)data;

More consistent naming methods.

- CMShape: Renamed the method: - (CMBody*)getBody; to: - (CMBody*)body;
More consistent naming methods.

- CMBody: Renamed the method: - (id)getData; to: - (id)data;

More consistent naming methods.

- CMBlastEffect: Added implotion methods, so now explosion and implosion are available.
- Refactored CMExplosionEffect to CMBlastEffect.

Posted 1 year ago #
Shilo
Master Sparrow

Very impressive Ronald, I just checked out the wrapper a few mins ago, and i'm having fun with the demos.

I did get an crash on the Planet Demo while trying to touch a planet.

"Aborting due to Chipmunk error: Unsolvable constraint.
Failed condition: determinant != 0.0
Source:../include/chipmunk/constraints/util.h:123"

Posted 1 year ago #
ronaldmathies
Moderator

Ah yes, i seem to be able to reproduce the problem (easily)... don't understand why i didn't notice that one :(. I'll look into it..

Posted 1 year ago #
WhiteGollum
Member

I'm actively using the great wrapper that Ronald share, and I'm facing the problem of designing and generating complex "objects".

I know this is not a Sparrow Issue but, as Ronald coded The CMDefaultLoader and share with this comunity, I hope someone is facing the same problem with the loader.

Does someone knows about an "object editor" similar to phisiceditor.de but able to generate plist files with multiples bodys, shapes, constrains, etc. That can be loaded with this CMDefaultLoader?

Posted 1 year ago #
ronaldmathies
Moderator

Hi WhiteGollum,

As far as i have looked around i only know two, one is VertexHelper and the other is PhysicsEditor.

VertexHelper is by no means really helpful since it does a terrible job with the convex / concave situations.

Also, something to keep in mind. The .plist file that is used in combination with the CMDefaultLoader is a self made up format. So there are probably no editors around that supports this file format.

I think you best bet is on PhysicsEditor, that one can handle most complex situations and is really good in handling convex / concave.

Can i ask what the reasons are why PhysicsEditor is not usable for you? It does support multiple bodies / shapes within a single .plist file. (Just add more images to the left panel).

Also, the new beta of physics editor now also supports more properties, the wrapper can't handle this at the moment but i am updating the code so it can handle the new properties...

Posted 1 year ago #
enbr
Moderator

Hi Ronald, I've been watching you develop this add-on from the beginning and would like to use it in a project but don't know where to start.
I'm guessing you are really busy and it's ok if you can't but I wanted to ask if you could make a very simple tutorial on using this wrapper for the wiki. I'm not looking for anything complicated, just how to do physics on rectangles.
Thanks,
enbr

Posted 1 year ago #

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