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

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Changing Box2D Body from Kinematic to Dynamic after contact

What is the correct way to change a Kinematic body into a dynamic body? context - I have a dynamic body as a projectile which has to be fired at a kinematic body (it is kinematic because i am ...
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How do I handle rope physics with fixed ends and a sliding weight?

I've been interested in rope physics recently—I've successfully implemented a simple Verlet rope with moveable ends. Now I am trying something a little different: I want to start by recreating the ...
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Get speed from vector using box2d and javascript

I need to find the speed of an object in a game. The game is made in HTML5 with jquery and jquery.box2d. For this I can use these methods: GetLinearVelocity().x; GetLinearVelocity().y; I'm then ...
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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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42 views

Creating a Player object in a physics engine

I have a working physics environment using Farseer - but how do I create a player object that can walk around? My current attempt involves applying forces to a rectangular body whenever keys are ...
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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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64 views

Box2D object wont move until tons of force is used

Im making a game for android im using LibGDX and Jbox2D it is a space flying exploration game controlled with the accelerometer. so I have set the world to no have no gravity. the objects in Box2D ...
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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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Is there a Box2d b2World::ShiftOrigin function in Libgdx?

Is there an equivalent Box2d b2World::ShiftOrigin function in Libgdx? I can't seem to find it.
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box2D and libgdx: Attach ParticleEffect to Body

Hello I am a newbie with libgdx, my question is: how could I add a Particleeffect to a Body that is moving? I searched about the matter and I didnt find anything related to it. I have the following ...
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How can I create a character design that maintains a fixed rotation body, while allowing the body's “arm” to rotate 180 degrees?

I am attempting to create a 2d shooter in Farseer Physics on the Xbox360. I have a player body which has a fixed rotation, as I do not want the body to rotate at all during gameplay. I am now looking ...
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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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83 views

Box2D platformer: Why does horizontal movement stop jumping?

I'm writing my sBox2D game character's movement code, but my implementation of jumping is failing: When I press the Jump key, the character jumps OK. However, when I press jump and another key (like ...
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46 views

Client-server architecture with box2d

I am running a client-server architecture with an authoritative server running box2d and the client running box2d as well. If gravity is set to 0, is there any point to linear interpolation and ...
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LibGDX Box2D TileGame Efficiency

I am trying to implement Box2D into my top down tile game in LibGDX. Each world consists of a set of chunks, and each chunk is 16 tiles wide/long. The maximum/minimum chunks loaded at one time is 9 (a ...
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How to create Whirlpool/Vortex effect?

Im trying to make a Vortex effect on a Circle Body that is a Sensor. I've been looking for this and all examples i look for are in C++ or Objective C and i dont seem to translate them well. when my ...
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50 views

How to move a body from one world to another?

I have a Box2D world for each level in my game. When a level is completed, I want the player to be removed from the completed level's world and added to the next level's world. How do I do this?
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Box2d bodies that are really close together, are getting “stuck”

I'm using a tiled tmx map, and I created a class that adds bodies to each tile within a certain layer. This has been working great so far except for when a character or an enemy moves around on the ...
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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 ...
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Box2D.js b2ChainShape

I'm using box2d.js (asm.js ported) and need to create a b2ChainShape. var bodyDef = new Box2D.b2BodyDef(); var fixDef = new Box2D.b2FixtureDef(); bodyDef.set_type(Box2D.b2_staticBody); var chain = ...
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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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59 views

Only render/calculate the chunks in frustum!

I have a 2D world in form of a Block[][]-Array that holds all the blocks of the world. Every block has it's own Box2D Body (I want a "minecraft"-like 2D world for this project). Naturally I don't want ...
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41 views

Drawing a object with Box2D and HTML5 canvas on current mouse position

I'm attempting to create a air hockey type game with HTML5 canvas and JavaScript, using Box2dWeb for the physics calculation. I need a way to draw the puck at the current mouse x and y position every ...
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103 views

Box2D body rotation with setTransform

I' having a problem rotating a body with setTransform(), The body has multiple sensors that should rotate with the player. The rotation works but it rotates around the bodys local 0,0 position instead ...
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90 views

What units is Box2d-AndEngine's velocity measured in?

I'm developing a game on AndEngine (with Box2d) and on iOS Sprite Kit simultaneously. I want the game's physics to be identical on both platforms. Sprite Kit uses Box2d internally for physics ...
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102 views

Making Player Jump

I have been editing a piece of code and I have already implemented gravity so I would like to know how i could make the player jump when the screen is touched. I would like the player bucket to jump. ...
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122 views

Ball bouncing with box2d in libgdx

I just started using Box2d and libgdx. I followed this tutorial, https://github.com/libgdx/libgdx/wiki/Box2d And a ball would bounce if I run the following code I took from the tutorial. // ...omit ...
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56 views

“Running” against a steep slope on a Box2D Platformer

Ive seen alot of pages talking about how to emulate a platformer on Box2D, specially about how people dont want to slide down a slope. Well, my problem is different and Im surprised I cant find ...
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32 views

[LibGdx]Moving a fixture on a body

I'm working with Box2D and I have a basic platform and a box bounces off of it. // Static Platform bdef.position.set(160 / PPM, 120 / PPM); bdef.type = BodyType.StaticBody; Body b = ...
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Box2DLights - the center of sprites are always 100% unlit (black) unless Xray is on

I'm using a ConeLight at 180 degrees, with this setup: pl = new ConeLight(rayHandler, 256, new Color(0.5f, 0.5f, 0.5f, 1f), 280f, 400 - x, 300 - y, 0, 180); And the object I'm casting a shadow on ...
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Box2D `ApplyLinearImpulse` is not working whereas `SetLinearVelocity` works

I need to mimic jumping behavior for the player in my game. Player consists of two fixtures with circle and rectangle shapes. Rectangle I use to detect ground and it is a sensor. Is some point 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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56 views

Bodies going through the walls of a box

I have a game where the user controls a box to collect falling balls. However, very often the balls will just fall through the walls of the box and be flung away. What could be causing the balls to do ...
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75 views

Multiple gravity “zones” in a world

I have a world that I want to divide in two like this: ____________________ | | | | | A | | | | | ...
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114 views

Box2d pathfinding using raytracing / predicted collisions

I have a Box2d/Cocos2d iOS game with enemies that attempt to follow the player (to attack). I'm working on improving the pathfinding logic so that the enemies won't crash into objects in the world. ...
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Why are my Box2D wheels slipping on ground?

I have a car, set up in Box2D as a rectangle connected with two wheels using WheelJoints: The wheels are defined as follows: FixtureDef wheelFixtureDef = new FixtureDef(); ...
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Get position of Fixtures

I'm constructing a Body (a box2d body using AndEngine) using multiple Fixtures and later I need to get the world position of these Fixtures. Currently I am trying something like this; // ...
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216 views

LibGDX Box2DLights shadow offset problem on bodies

Hello I just started to use LibGDX, and it's awesome. I looked at the Box2DLights library, and started to learn how the lighting work here. I got something up: As you can see, it works, but the ...
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Love2D Box2D RevoluteJoint and Anchors

and apologies in advance for this fairly random question. I'm using Love2D 0.9.1 and Box2D to create two bodies joined by a revolute joint. A simplified representation of the two bodies is a Sphere ...
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In JBox2D, where is the correct place to interact with Body objects? step() method?

QUESTION: In an application, where is the appropriate place to put the code to interact with the Body objects? By 'interact' I mean Get position Determine actions Apply impulse Would it be ...
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What's the difference between Box2D and tweening?

It seems like Box2D can be used to move sprites across the screen, so how does this differ from tweening? Is it that Box2D is for physical collision detections and tweening is just animations?
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Box2D collision damage calculation from postSolve or not?

I'm using postSolve to get impulse then calculate damage base on that impulse. But there's some issue: Stability The damage isn't stable. When the same ball is hitting with same speed, the damage ...
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136 views

How can I predict player-to-projectile collisions in Box2D?

I'm making a real time shooting game with Box2D as the physics engine. The gameplay is mostly about trajectory, like Angry Birds. I want to make a slow motion effect and move camera to the player when ...
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54 views

How can I add an impulse to specific rigid bodies at rest?

Scenario Rocks falling down a rocky slope, with a flat surface at the bottom. When they land on the surface, the rocks move slightly before coming to a rest. GLESDebugDraw shows the bright orange ...
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Box2d - Attaching a fired arrow to a moving enemy

I am firing an arrow from the player to moving enemies. When the arrow hits the enemy, I want it to attach exactly where it hit and cause the enemy (a square) to tumble to the ground. Excluding the ...
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sprite reset method not working in update thread(andengine)

I have sprite array with length of 8 and I am trying to reset sprites position in scene's update thread but it doesn't work. However I tried to reset sprites in sprites modifier listner which works. I ...
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Complex Body with multiple BodyDefs

My complex body is made up of several parts some of which are static and some are dynamic and have specific positions relative to each other. Because the static/dynamic property and position goes in ...
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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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42 views

Inertia in flight simulation using box2d

I'm trying to simulate flight using box2d and libgdx. The main problem I am currently experiencing is with inertia: since there is no air, the plane looks like it were drifting. I wasn't able how to ...