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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balloon ligher than air with libgdx, impementation of FixtureDef.density, gravityScale, linearDamping?

I use libGdx/box2d's physic. My intention is to create a balloon filled with helium (a body, what hovers above a surface, if we apply a little force to it - it moves fast but not far, if we push ...
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generate box2d bodies from isometric tiled map

I followed the tutorial here to generate box2d bodies from a tiled map and that worked fine.... for orthogonal tiled maps. Unfortunately isometric maps use their own coordinate system where (0, 0) is ...
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beginContact triggered more than once on some objects

Short version: It looks like beginContact is detecting continuous collisions. I'd like to avoid that. Long version : I use Box2Dweb to write a 2D platformer. It's my first game using this lib, and, ...
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710 views

changing body type without change of center of mass

I have an box2d project with some bodies in it, which move around without any user interaction. But if the user selects one of the bodies, he should be able to move it around just like he wants to. ...
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Sizing a Box2D ground object

I am developing a platformer game using SDL2 for graphics and Box2D for physics. I am currently designing my levels and would like to know if it is better to make the static part of each level (ie: ...
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Calculate the rest length of a box2d distance joint

Given the length of a distance joint along with its frequency and the mass of the bodies involved, is it possible to determine the final rest length? I'm only interested in the vertical axis if that ...
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Using Box2D in LibGDX, is there a reason a fixture set to be a sensor would only -sometimes- detect a collision?

I am working on a 2D game in LibGDX. Currently, I am testing interactions between a player's weapon and enemies - in particular, a sword and an enemy monster. The player has a hurtbox and the sword ...
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Farseer: Friend/Foe Collision - cannot push foes but friends

we are using Farseer in our project and I try to find a setup to achieve the following quite complicated collision behavior: Friendly Units can push each other aside. However, the push should be a ...
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Mouse click coordinates not mapping to Box2d world

I'm using Box2d in Java with OpenGL, trying to detect if a mouse has clicked on a Body. But having trouble mapping mouse coordinates to Box2d world. I have a Body positioned at 20.0f, 30.0f in the ...
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Libgdx/Box2D PolygonShape has no position… well, what now?

As my prototype works perfectly fine I want to advance to more fun areas of the project and add a more complex player-character body. So for Box2D I figured I'd need multiple fixtures, like one for ...
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How to tell if a fixture is being squeezed by two other fixtures in Box2D?

Let's say I had a ground fixture, a player box, and a kinematic block moving up and down. If the player stands under the block, weird things happen. I want to simply play an event where the player ...
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Box2D random crash when adding joints

I'm currently working on a project which uses Box2D, when the player uses a certain key it should anchor to the ground. For that I use a weld joint, but when I add the joint the game will sometimes ...
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unity4.3 rigidbody2d unexpected force behaviour

So guys ive edited the question and here is what my problem is i have a player which has a rigidbody2d attached to it.my player is able to doublejump in the air nicely and stick to walls when ...
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74 views

Need to join 2 bodies via weld joint but not on center of mass

I have successfully join 2 bodies via weld joint , but my problem is I want to join corners of bodies not on centre of mass. Is there any way to achieve this? Above image consist 3 polygon body that ...
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197 views

Box2D Qt wrong collisions

I am working on a simple Box2D game (with Qt), but my objects don't collide correctly: As you can see on the picture, objects try to go through each other and slide over. My b2World: b2Vec2 ...
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290 views

Image Texture Tracing Algorithm - Cocos2D Box2D

Context: I am working on a 2D Destructible Terrain engine for Cocos2D with Box2D. All images, when a level loads, have their border's traced and cached for the purposes of forming Box2D b2EdgeShape ...
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Why do restitution values less than one still cause infinite bouncing in Box2D?

I'm currently trying to implement basketball bouncing into my game using Box2d (jBox2d technically), but I'm a bit confused about restitution. While trying to create the ball in the testbed first, ...
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How to properly add texture to multi-fixture/shape b2Body

Hello to everyone this is my first poste here I hope that will be not fail start. At start I must say I make part 1 in Ray's Tutorial "How To Make A Game Like Fruit Ninja With Box2D and Cocos2D". But ...
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Black screen when launching on phone

I am coding a game in libgdx. While adding the background I used the html module to watch the results fast and easy on my computer. But when I try to see it on my phone I just get a black screen. My ...
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TypeError: R[o5R.F6s] is not a function in changing states in phaser box2d

i build my game using phaser.2.4.3.min.js and phaser.2.2.2.box2d.min.js When trying to change states this error is being raised TypeError: R[o5R.F6s] is not a function and i can't seem to figure out ...
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DynamicBody diving into StaticBody

In my game I want a DynamicBody to dive down into a StaticBody. I set up both bodies. At the moment they are colliding. How can I get my DynamicBody to dive down? Is it going to work with this ...
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Box2d Coordinate System

In the game I'm trying to code I got to have two bodies. One StaticBody and one DynamicBody. I want to have the DynamicBody on top of the StaticBody. Somehow all I get is this: Is it possible that ...
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Movement through forces and impulses

I'm trying to get some decent-looking movement in my game using this tutorial. In the image below... something crazy is going on. What should happen is that the NPC should start on the left side of ...
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31 views

Box2D collision between dynamic body

I'm implementing Box2D for my 2d top down LIBGDX game and i have some struggle with two dynamic body. Currently, my two bodies are created that way : BodyDef bodyDef = new BodyDef(); ...
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boost/geometry replacement in Java/for the JVM (Destructable Box2D terrain)

I'd like to reimplement https://github.com/seemk/DestructibleBox2D in Java. The main problem is finding an adequate replacement for the boost/geometry library. Any ideas?
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Raycast trouble

i'm having some trouble with the RayCast. I'm raycasting from the player position and my mouse position. I have this situation : http://i.imgur.com/h7iplnY.png (the white line is a representation of ...
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Which Box2D-like physics engine parameters need pixel conversion?

The official guide does not have any useful details on the matter: http://www.box2d.org/manual.html Position is an obvious one. What about velocity? Density? Anything else? Update: the context is ...
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Use libgdx box2d for dynamically generated top down map

So, I've already found some information on how to use box2d and tiledmap together. Since I want to generate my top down map (100 by 100 tiles), I thought about only using box2d. The tiles would be ...
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LibGDX , Box2D body Mass Center

I am creating complex bodies using this editor. But the mass center of the body is not in the right place , when I apply force to it it begins rotating . So I am confused why is the masscenter in the ...
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Adapting qml-box2d to work with QGraphicsScene: transform origin is incorrect

I'm taking the convenient QObject wrappers from the Box2D QML Plugin and using them with a QGraphicsScene-based game. My motivation is to save time writing them myself, as I need to expose stuff to ...
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Why does physics interpolation give me periodic jumps/flickers?

I have seen this question but it didn't solve the problem. I have followed the same steps as in this article. What I notice in my Android game is that my interpolation alpha (or fraction or ...
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Setting Up the PTM_Ratio for Different Devices

I want to set the the physics for my Game and I have used Box2d for the Physics Simulation. And to do that I have set the PTM_Ratio to 32.0f.But When I run my Game on Different Android or iOS Devices ...
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Box2d c++ can't see b2PolygonShape

i try to follow this tutorial and convert it to c++ http://www.emanueleferonato.com/2009/04/06/two-ways-to-make-box2d-cars/ the second part of the tutorial Now im facing very strange Behaviorno ...
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Can't perform normal jump after applying revolute joint

I have encountered the following problem: I have two PolygonShapes which I had connected with a RevoluteJoint. The first body is called square the second is called weapon, before connecting the two ...
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Box2D replace Fixture not working as expected

I am using box2D to develop a simple game, and I am using the Physics body editor by Aurelien Ribon to load the fixtures into bodies. I have written the following method which should scale my ...
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Preferred way to integrate box2d with SFML

I'm trying to integrate Box2D with sfml. My current solution is to have overloaded functions creating sfml shapes from box2d fixtureDef shapes. I store created sfml shapes under the name 'visual' in a ...
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mouseWorld Coordinates Box2D

I have one simple question in Box2D: if you want to get the world coordinates of mouse, this is the function you gonna use in Java: void update(int x, int y) { if(mousejoint !=0) ...
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How do I get the impulse of a collision from Box2D in LibGDX?

I am developing a game using LibGDX and Box2D. I want to get the force or the impulse when two bodies collide, but I can't find the right way to do that. How can I use a ContactListener to get the ...
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Box2D Bomb Explosion

I'm using CircleShape to create my bomb, but now, after throwing it I want it to explode after 4 seconds. public void setUp(){ BodyDef body = new BodyDef(); ...
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Box2D thow ball from PIXELS posisiton

Here are my enemy movement function. I want that my enemy in random Y-position throw a bunch of things in to the player. And I want to implement physics using Box2D. But I know that Box2D workd only ...
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Box2d - body size or spatial distribution matters for better simulation?

Box2D better works for limited sizes: Box2D works with floating point numbers and tolerances have to be used to make Box2D perform well. These tolerances have been tuned to work well with ...
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Change a vertices and display corner of a polygon

I'm currently building a level editor for my game and i'm having some trouble on how to change vertices of a polygon. Basicly i searched the web trying to figure out how to update the vertices of a ...
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272 views

Move body LibGDX Box2D

Hello I have a body and I want to move it. When I press the mouse button my body should move at that position (on the const speed)on the screen. I have override two methods(x1, y1 - point where my ...
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671 views

Box2D shape/fixture position vs. body position

I load my rectangular shapes from a simple Tiled level into libGDX and want to create a physics world out of it via Box2D and attach sprite assets for rendering. I get the tiled object layer and ...
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libGDX fixed object and camera do movement

I develop game to andorid and there is moving object with arrows - simple movement like in RPG games. I did: camera.position.x = PIXELS_PER_METER*man.body.getPosition().x; camera.position.y = ...
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Box2D - create object with different physic parts

I have object with physic: BodyDef bodyDef = new BodyDef(); bodyDef.type = BodyDef.BodyType.DynamicBody; bodyDef.position.set(position); bodyDef.angle = angle; ...
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Destroying fixtures in Box2D/AndEngine

In my game I need to break of parts of a body when the body crashes into something too violently. Currently I do that by by getting all the normal impulses of the ContactImpulse and if the max value ...
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Intersection issue with box2d in iOS

I'm trying to use the code here http://www.iforce2d.net/b2dtut/raycasting So I can know whether a line cross a box2d object or not. It half works, in that when the line crosses the object it does ...
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How can I make a swinging rope?

Base question: How can I make a swinging rope in box2d? Context: The idea is to have a rope where the player can grab it, swing a little bit to get more "momentum" and reach the next platform. Like ...
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Speed seems random with constant impulse

I'm shooting an object from the top vertex of a triangle using Box2dWeb. The issue I'm having is that the projectile speed seems to be fairly random, even with applyimpulse set to a constant. The ...