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

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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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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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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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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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64 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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46 views

Box2d linear velocity unit in AndEngine

I’m using AndEngine with Box2d for a game with many moving objects. I’m developing in iOS Sprite Kit simultaneously . in iOS Sprite Kit , I use, physicsBody.velocity The physics body’s ...
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96 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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63 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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36 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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25 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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70 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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67 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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42 views

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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130 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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129 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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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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135 views

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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59 views

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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36 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 ...
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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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71 views

How to make player rotate towards mouse [duplicate]

I'm making a top down shooter with Three.js and Box2d. I'm displaying all of the graphics in 3d, but all of the physics are done in 2d, so it's sort of like super smash bros in a way. Anyway, how can ...
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142 views

How to optimize a box2d simulation in action game?

I'm working on an action game and i use box2d for physics. The game use a tiled map. I have different types of body: Static ones used for tiles Dynamic ones for player and enemies Actually i ...
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55 views

box2dlights conelight rotation is off

I'm using libgdx/box2dlights for my game~ I have a conelight set up as such: ConeLight cl = new ConeLight(rh, 32, new Color(0f, 0.0f, 0.0f, 1.0f), 3, 0, 0, 0, 1); where "rh" is a RayHandler set to ...
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95 views

simple collision detection with box2dweb

im beginner in box2dweb that version of box2d for javascript i wrote simple gravity system and i want to detect the collision between the box and the ground , when the falling box hit the ground ...
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revolutejoint doesn't seem to rotate

I have a revolute joint set up as such in libgdx + box2d: RevoluteJointDef rjd = new RevoluteJointDef(); rjd.initialize(body1, body2, arm.getWorldCenter()); rjd.motorSpeed ...
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Box2D and randomly generated tilemaps

I am making a 2D Terraria-style sidescrolling game. I want to use box2d for the physics. However, I am using tilemaps for the maps, and I do not know of a processor-efficient way to use Box2D bodies ...
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how do I create a moving type of block like in Mario[box2d]

I want to create a block which only moves up and only when hit from below. I am trying out a distance joint and I read it can be used as a spring, is this the correct solution? the way I have tried ...
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Box2d not showing consistent behaviour with sprites

Box2D newbb here. My question is in regards to this create js project:http://mboyeman.com/dashingdog/ (runs best in IE...:3) I wrote a function(assignBlockBodies) to give 2D Edges to sprites based on ...
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417 views

LibGdx sprite rotation vs Box2D physics rotation problem

LibGdx sprite rotation vs Box2D physics rotation problem Tearing my hair out on this one. I am an experienced software developer, but very new to LibGdx and Box2D development. I am writing a game ...
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How to set LinearVelocity exactly in onSceneTouchEvent?

I'm beginner in Android programming. And i use AndEngine GLS2 with Body and AnimatedSprite. I have a object ball and i want to move it to follow my hand. This is description for my idea: And my ...
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126 views

determine collision angle on a rotating body

update: new diagram and updated description I have a contact listener set up to try and determine the side that a collision happened at relative to the a bodies rotation. One way to solve this is ...
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116 views

Change the shape of body dynamically

I have a problem where i have a ballon which i need to continuously inflate and defalte in update method, I have tried to used setScaleCenter but it is not giving desired result. Below is a code i am ...
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101 views

Using Box2d to model rotating turret

I would like to model a rotating "turret" on top of a tank-like object in 2D from the side view like pictured here: Notice the faint outline of a gun protruding to the upper left courtesy of ...
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Libgdx Box2d createfixture crashes vm intermittently

I have a hard to debug problem. I have a Box2D game which creates a wheeled vehicle. I want the vehicle body to reflect when it goes from moving left to moving right. to do this i set a flag in a ...