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

learn more… | top users | synonyms

2
votes
4answers
219 views

How to make sure that when two bodies collide, there is only one collision detection on box2d?

I'm using LibGDX with Box2D and, when two bodies collide, the collision is detected multiple times. Here's the code: public void preSolve(Contact contact, Manifold oldManifold) { Body a = ...
2
votes
3answers
309 views

Dynamic Hills like Contre Jour in Cocos2d

I'm interested in maps/environments which are flexible and change at runtime, such as those in Contre Jour. I have looked for a long time to find out how to make this effect, but I couldn't find an ...
0
votes
2answers
615 views

Libgdx box2d crashing

im making a game in libgdx which i having a bunch of circle bodies floating around in space and when the player's body crashes into another body, that body deletes and creates two smaller bodies ...
0
votes
2answers
688 views

Move Box2D body towards mouse click

In a top down game using Box2D, I would like the player's Box2D body to rotate towards the mouse click, and then move to a point on mouse click (move, not teleport). I have worked out the rotation ...
4
votes
1answer
297 views

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 ...
3
votes
1answer
127 views

Creation of a tiled map editor polyline in box2d is not working correctly

I'm currently trying to create a box2d polyline object in my libgdx game, but it's not working as expected. To get a better picture of my subject, have a look at how it should look like, and how it ...
2
votes
1answer
359 views

LibGDX Box2D Lights - Illuminate background

I have a box2D world made of tiles. I use a custom DirectionalLight for light up the scene from above (It shines through transparent blocks [eg.: the water] more deeply). The problem is (as expected), ...
2
votes
1answer
464 views

Wheel Joint Implementation in AndEngine

I am currently developing car game in AndEngine. In which I was using revolute joint for car wheel and chassis attachment. But my friend suggest me that use wheel joint for that purpose for better ...
1
vote
1answer
54 views

How to handle two players playing on one keyboard with Box2D (LibGDX)?

I'm making a racing game with LibGDX and Box2D. I've been using this tutorial to implement the basic physics, and it works properly. My main problem is to implement two different sets of keys ...
1
vote
1answer
38 views

Box2D fixed timestep updating is twitchy on constant FPS

I'm messing around with libgdx and box2d and I'm trying to implement sidescroller movement with fixed timestep logic according to the famous Fix Your Timestep! tutorial/guide. However, logic updating ...
1
vote
1answer
67 views

LibGDX Box2D texture on dynamic generated body

I'm creating a game that is similar to hill climb racing. I've generated the ground and now I want to add texture to the ground. Here is a screenshot of a game Here is my code (I create ground using ...
1
vote
1answer
50 views

Problems managing collision filtering

I have my character fixture and body(is a tank), so when I press the screen it throws a rocket(which also has a body and a fixture) that the player can controlll touching the screen. My game also has ...
1
vote
1answer
218 views

Rotating towards a point in Box2D

I'm using Box2d as my physics engine and I'm trying to solve what would normally be a simple problem but what has become a nightmare for me and preventing me from finishing my app. (6 months work) ...
1
vote
1answer
620 views

Lighting shadow casting sprites with box2Dlights

I currently have something like this using box2Dlights Ideally, I would like objects casting shadows to be lit, so the object is lit but there is still a shadow cast around it. Right now the object ...
1
vote
1answer
869 views

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 ...
1
vote
1answer
1k views

Drawing Shape in DebugView (Farseer)

As the title says, I need to draw a shape/polygon in Farseer using debugview. I have this piece of code which converts a Texture to polygon: //load texture that will represent the tray ...
0
votes
1answer
12 views

Box2dWeb: rotating object about a point

I am having problem rotating box2d object back and forth around a point. To better understand my problem i have prepared an example clicking on key rotate the paddle when u click again the paddle ...
0
votes
1answer
28 views

Libgdx + Box2d working with 2 cameras

Recently I have read that you can work with 2 cameras whenever you involve Box2d, which only works in meters. In my Renderer class, I receive all the entities in the game and then draw them. I work ...
0
votes
1answer
47 views

How to unload/remove body components in Box2D?

I want to know how to release/clear/remove a variable. (specifically b2BodyDef, b2Body, b2FixtureDef, b2PolygonShape types.) I've heard there's a keyword called delete, guessing by it's name it may ...
0
votes
1answer
88 views

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 ...
0
votes
1answer
34 views

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 ...
0
votes
1answer
104 views

Set Position of multiple bodies

I have a character composed of five bodies which are tied together by a lot of joints. On of them is the overall chassis, to which all forces and impulses are applied to move the whole Character. All ...
-1
votes
1answer
313 views

How to draw a curved line in Box2d?

I need to draw a curved line, I have searched the Internet but found nothing that would suit my needs. I used b2ChainShape but it's not completely what I need. How can I draw a curved line with ...
-1
votes
1answer
61 views

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?
-1
votes
1answer
165 views

Collision function calls before colliding

My Box2D contact listener class is calling post solve and beginning the contact function before colliding? This is causing my object to bounce back before hitting the ground. What could be causing ...
-1
votes
1answer
653 views

Box2D Static-Dynamic body joint eliminates collisions

I have a static body A, and a dynamic body B, and a dynamic body C. A is filtered to not collide with anything, B and C collide with each other. I wish to create a joint between B and A. When I ...
-1
votes
1answer
2k views

Create Box2D and engine polygon Box2D body without sprite

Hey I have created my body using following code: (please read full description) Body polyBody; final BodyDef mBodyDef = new BodyDef(); mBodyDef.type = BodyDef.BodyType.DynamicBody; ...
-2
votes
1answer
93 views

Is it possible to use Box2D or Chipmunk in Swift & Cocos2d?

I am new to iOs programming. I wonder whether it is possible to use Box2D physic engine in Cocos2D with Swift. I am asking because I started to learn Swift. And I create Xcode project from ...
0
votes
0answers
19 views

Box2D revolute joint positioning

I'm trying to auto test some basic assumptions about how bodies tied together with a revolute joint should be positioned: void tst_GameController::physicsJointInitialPosition() { ...
0
votes
0answers
19 views

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 ...
0
votes
0answers
106 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(); ...
0
votes
0answers
38 views

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?
0
votes
0answers
28 views

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 ...
0
votes
0answers
42 views

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 ...
0
votes
0answers
66 views

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 ...
0
votes
0answers
70 views

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 ...
0
votes
0answers
75 views

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 ...
0
votes
0answers
117 views

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 ...
0
votes
0answers
1k 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 ...
0
votes
0answers
316 views

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 ...
0
votes
0answers
34 views

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 ...
0
votes
0answers
124 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 ...
0
votes
0answers
144 views

Shifting the camera and setting a new scene when using Box2D

My jsFiddle: // START -- MOVE CAMERA var p = new b2Vec2(); p = (ball.body.GetWorldCenter().x) * physics.scale; pos.push(p); var length = pos.length; var s = (pos[length - 1] - pos[length - 2]); //in ...
0
votes
0answers
80 views

Box2D—Dropshadow

I am about to create a Jump'n'run game using Box2D for the physics. I am asked to add a Dropshadow to the main Character, but as I noticed this could become quite complicated. Basically the Light ...
0
votes
0answers
178 views

Simulating a single water droplet in Box2d

This is for a class project. The main character in the game is an oil droplet and we're trying to simulate it using Box2D. One of the levels in the game is where the oil droplet is in contact with ...
0
votes
0answers
100 views

Prismatic Joint causes a crash-Box2D(cocos2d)

tried to set up a prismatic joint, but I get this error upon run time: Assertion failed: (IsLocked() == false), function CreateBody, file ...
0
votes
0answers
73 views

Andengine Box2D Physics “disappearing”?

I have problems with my PhysicsWorld in Andengine GLES20. Sometimes when i first load my app and level there is no velocity added to my bodies. they also rotate slower as it seems. This also happens ...
0
votes
0answers
1k views

Box2D Soft Body Wheel in Unity3D

I was watching this video made with IForce2D, its about creating soft bodied wheels in box2D. http://www.youtube.com/watch?v=F-aDMZUVw0c I wanted help in being able to increase the Radius of the ...
0
votes
0answers
460 views

box2d's ApplyForce works wrong after cocos2d-x's replaceScene

i'm practicing making a breakout game, using cocos2d-x 3.x and box2d, referencing here. i create a ball in the scene's init function and apply force. when ball hits bottom wall, if i touch screen ...