Questions tagged [box2d]

Box2D is an open-source rigid-body 2D physics simulation library for games, written in C++, with ports in various languages

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Stretching textures for CCSprites in Cocos2D

I'm making a game for iPhone and iPad w/ Cocos2D and Box2D. I scale the size of square objects ("blocks") using a pixel-to-meters ratio depending on the particular device. Can I stretch or shrink ...
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1answer
764 views

How to create a vertex array from any shape in JBox2D?

I have a code, that add a vertex array to a shape, my code is: ...
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1answer
2k views

Get Vertices of a Shape/Body in Box2D

Is there a way to do it? I can get only polygon_shape's vertices, but i want circle, box, etc too. How to do it?
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1answer
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Get shape of my bodies using Box2D

I would like to get the shapes of my bodies, but I can't get anything, only null. Why? Here is the relevant code section: ...
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1answer
250 views

Mouse joint isn't restricting the ball from going to the other part of the screen

I'm developing a application in cocos2d using the Box2D framework, but unfortunately I am having issues. I'm not able to restrict the orange ball in the half screen area, taking the image below as ...
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1answer
5k views

Basic Box2D collision detection

I don't understand how to listen for collisions in Cocos2D/Box2D. Say I have two dynamic circle bodies. One is very small and the other is relatively large. When the small circle collides w/ the ...
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2answers
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Getting started with Box2D for iOS

I just want to run any Box2D "Hello World" or test apps. I've downloaded the source twice (zip file the first time and via svn the second time), followed the build instructions (do stuff w/ cmake, "...
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1answer
368 views

Box2D stable range and position

Box2D marks stable range of object size is 0.1M ~ 10M. This specifies object size range. How about space size? If I make an 1M object at (1000.0f,1000.0f) position? Is it can be stable? Or should I ...
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1answer
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cocos2d: syncing CCAnimation frames with Box2d Shape manipulations

my cocos2d game currently has a ccsprite attached to a box2d body. during the game i apply different CCAnimations on my sprite, i would like to perform certain manipulations to the box2d body ...
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1answer
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How to get local point inside a body where mouse click occurred in box2d?

I need to find out the point inside a body, lets say a rectangular object, where the mouse was clicked on. I'm makin a game where the force will be applied depending on where the mouse was clicked on ...
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2answers
2k views

Using box2d DrawDebugData with multi layer scene?

In my Game, a Scene is composed by several layers. Each layer has different camera transformations. This way I can have a layer at z=3 (GUI), z=2 (Monsters), z=1 (scrolling background), and this 3 ...
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2answers
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Spawning bullets on command in Box2D

I'm making a simple bullet hell game but I can't figure out how to get my character to shoot. Lets say I have bulletBody and shipBody, how would I continually spawn bulletBodies using the shipBody ...
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how can i move static box2d object

how can i move static box2d sprites. i have tried this tutorial from . http://www.raywenderlich.com/475/how-to-create-a-simple-breakout-game-with-box2d-and-cocos2d-tutorial-part-12. I managed to add ...
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4answers
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Best strategy (tried and tested) for using Box2D in a real-time multiplayer game? [duplicate]

I am currently tackling real-time multiplayer physics updates for a game engine I am writing. My question is how best to use Box2D for networked physics. If I run the simulation on the server, should ...
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1answer
528 views

Strangeness when simulating a chain

I'm using box2d and I simply hook up 10 points each with a similar length constraint to the adjacent point. When I move 1 point, the others follow just like a rope/chain. Just like one would expect. ...
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1answer
277 views

How to use the testbed with box2dflash?

I have made games with box2dflash, but how much ever i have wanted to try out the test bed, the resources on the net don't help me. I have a folder called Testbed and various Test???.as files inside ...
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Is it worth it to use Bullet for 2D physics instead of Box2D for the sake of learning Bullet?

There isn't much more to the question. I'm not concerned about overhead, as I'm sure they are both fine for my purposes. Basically, I am familiar with Box2D concepts because of the Farseer Physics ...
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3answers
781 views

What do I need to change in Box2D to work in pixels?

Box2D seems to be set up in such a way that you cannot work in pixels (i.e. physics scale = 1). It produces very strange results as it hits maximum speed limits at low speeds and looks very strange. ...
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1k views

How do you create your levels containing curved slopes in Box2d?

I have just started developing games for iPhone in Cocos2d and am currently working on a Box2D prototype. I know this is not an easy start, but I have experience in the AS3 port of the physics engine. ...
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2answers
2k views

How to implement 2d explosions that will cause damage taking into account covers and distance?

How can I implement a 2D explosion in a way that it will cause less damage to characters that hide behind crates or other cover? Ideally damage will depend on the strength of the cover (e.g. metal ...
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3answers
5k views

Polygon/Shape definition changes in Box2D 2.1

I was going through a pretty good tutorial on Box2D here, but I ran into a problem when he made a b2PolygonDef, because the tutorials were made in 2.0, and I'm ...
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2answers
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Making a character move along a curved slope in a World with gravity

I have seen this game Fancy Pants 2 . And the thing I noticed apart from the physics and beautiful animations is that the character is moving along slopes , even curved slopes. I have little ...
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1answer
482 views

How can I copy or back-calculate definitions for an entire b2World?

I'm working on a platformer where I'd like to be able to move or copy bodies between multiple Box2D b2Worlds. The desire has cropped up three times now - moving objects between documents in my editor, ...
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1k views

How to create simple physics for a group of balloons colliding in the screen (2D)

The game is 2D, how can I make simple physics for a group of balloons colliding in the screen. What I need is the balloons not to overlap and to bounce when they reach the limits of the screen or ...
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Box 2D Set Origin

I'm trying to set the origin of a box2d shape. By default, a shape rotates around the center. But I'm trying to get it to rotate around the left of the shape. Like a clock for example. I've heard of ...
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2answers
340 views

In Box2dFlash my b2body gets detached from my Sprite after I use setXForm()

I have a scenario where I have red coin in a Carrom board game which should be moved outside of the visible window when it is pocketed, also if any coin either white or black is not pocketed in the ...
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1answer
896 views

Problem with box2d at beggining

I have problem with simple box2d physics: I have two bodies : 1 - static box , 2 - dynamic box. I only want to this dynamic box fall on this static, and lay. But now it looks like that at end , ...
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2answers
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cocos2d Merging box2d bodies

i'm using cocos2d to build an iphone game. my game currently has two sprites: one for the main character and another for an item i should carry once he gets on him. the main character and the item ...
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10k views

Using The Box2D Polygon “Set()” function?

I'm using the Box2D physics engine. And there's a type of shape for box2D called b2PolygonShape. In this class, you can create polygons. There is also a Set() function that takes an array of points ...

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