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

learn more… | top users | synonyms

1
vote
1answer
97 views

Box2D relations

As far as I know, the unit in Box2D is meters. When I use Box2D in Processing with JBox2D, I set the "world size" as the window size specified in the setup(). Now I'm wondering if there is any ...
5
votes
2answers
534 views

Running multiple box2D world objects on a server

I'm creating a multiplayer game using LibGdx (with Box2d) and Kryonet. Since this is the first time I work on multiplayer games, I read a bit about server - client implementations, and it turns out ...
1
vote
0answers
67 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 ...
2
votes
1answer
213 views

JBox2D Polygon Collisions Acting Strange

I have been playing around with JBox2D and Slick2D and made a little demo with a ground object, a box object, and two different polygons. The problem I am facing is that the collision-detection for ...
1
vote
1answer
579 views

Movement of body after applying weld joint

I have two rectangular bodies. I've applied Weldjoint successfully on these bodies. I want to move that joined body by applying linear impulse. After weld joint, these two bodies becomes single body ...
0
votes
1answer
2k views

coloring box2d body in LibGDX

I want to color polygon of box2d in LibGDX. Found below useful class for that. http://libgdx.badlogicgames.com/nightlies/docs/api/com/badlogic/gdx/graphics/glutils/ShapeRenderer.html But, it is not ...
0
votes
1answer
769 views

Box2d making a body follow the mouse accurately

I am trying to make a box2d b2Body follow my mouse position. This is the code I am using at the moment but it is not performing very well: deltaPos = mousePos - body->GetPosition(); deltaPos *= k; ...
0
votes
1answer
133 views

Move background with the player location

I want to move background with player location in ios . I have implemented the infinite parallax background by using the CCParallax class but i don't need it. I want to do something similar to this ...
3
votes
1answer
835 views

box2d raycast filter category

I am trying to filter a category in my ray casting (jBox2D within libGDX), which should return the closest object that does not belong to the category LEVEL0. I've tried a plethora of approaches, but ...
0
votes
1answer
85 views

Getting a sprite from multiple sprites for right material pattern

Not sure how accurate the question was but I'll put it this way. I'm developing a game where player will construct his/her own stuff, like bridge, building etc. using cocos2d-iphone and Box2D. First ...
4
votes
3answers
1k views

How to make Box2D bodies automatically return to a initial rotation

I have two long Box2D bodies, that can collide while moving one of them around with MouseJoint. I want them to try to hold their position and rotation. Blue body is moved using MouseJoint (yellow) ...
-1
votes
1answer
475 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 ...
0
votes
1answer
373 views

Remove a body when touched in LibGDX(Box2D)

I am using LibGDX to create a new project. What i am trying to do is, i load bodies from a tmx file into levels which works fine. The bodies also has a sprite with them. The problem is, is i would ...
1
vote
2answers
515 views

How do I make a Box2D object that makes objects passing through it slower?

I wish to have a sort of "slow motion" or "slow down" effect on a players character when they walk in a mud area, usually the character velocity is 3f constant in any one direction. The problem is I ...
3
votes
1answer
355 views

Making a 2D TMX tile map

Should there be a specific link between the characters height as well as the tile size for the tile maps? That is if a tile is 32x32 does that mean that a character sprite has to be the same size? ...
1
vote
1answer
101 views

How to reduce the time it takes to speed up an object?

I have a body that I am applying a force to every step. However, I it takes a significant amount of time for it to speed up, which I do not want. Is there some value I can adjust to help with this?
0
votes
1answer
371 views

Getting body position

I am using BodyA.getPosition().x and BodyA.getPosition().y to get the x and y vector of a body location so i may attach some text above its head, but the log of that position prints out something like ...
0
votes
1answer
107 views

Encapsulating Box2D C++ two virtually the same functions

I have two functions that are virtually the same with a few small differences in code, one to create a static body and one to create a dynamic body, however if I call both of them it results in a ...
6
votes
2answers
382 views

How do I duplicate a Box2d simulation, mid-simulation?

I want to serialize the state mid-game, send it over the network to an identical computer (same CPU, same OS, same binary), load it there, and have the two games run in tandem doing the exact same ...
0
votes
1answer
419 views

Showing trajectory indicator

From the image you can see that the ball fired on the left that fire behind it, does not match the calculated trajectory. Im drawing the ball trajectory using an equation from a SO question, this is ...
0
votes
1answer
94 views

libgdx fixture is giving unresponsive error

need some support. I am novice in libgdx game engine. Below is my code package com.game.box2d.fruitcart; import com.badlogic.gdx.Game; import com.badlogic.gdx.Gdx; import ...
6
votes
0answers
362 views

Box2D strange collisions (jitter) on sharp edges [closed]

I'm currently developing 2D side scroll game with Libgdx + Box2D. And I'm facing some problems with ChainShape (the ground) and PolygonShape (the cart body) collisions. Please look at this video: ...
1
vote
0answers
178 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 ...
2
votes
1answer
4k views

Libgdx explain steps for beginner to create and use image as a box2d body [closed]

I am basically from corona background and new to LibGdx , familiar with stage and actor from scene2D. Now wants to use physics body from box2d in the game besides using actor from scene2D. But I ...
0
votes
1answer
946 views

Movement with box2d using libgdx

I am pretty new to using physics engine and would like to know what is best practice for movement of playercharacters. Currently I have a class called Hero that has a CircleShape and when the user ...
3
votes
2answers
273 views

Box2d : How to apply a force to keep swinging from left to right?

i'm losing myself in this... Situation: Working on a game in cocos2d with box2d and I have a ropejoint between one fixed body and one dynamic body. When I drop the dynamic body is swings from left ...
1
vote
1answer
621 views

Box2D: Efficient method to create b2Chainshapes for a tile-based map?

I'm working on a platforming game with tile based levels. I store the collision model for my tileset in an array. This is how the collision model for a 4x4 tilesheet would look like (I can't post ...
0
votes
1answer
339 views

Rotating an object about a point (2D) using box2d

i just started developing using box2d on flixel and i realise the pivot point of the rotation of an object in box2d is set to the center of an object. i had read on forums and i found out that ...
2
votes
0answers
428 views

Choosing a level editor of a 2d platformer [closed]

I'm working with a small team on a 2D platformer game in Java (LibGDX) that uses Box2D for physics. Our team is looking for a tool to make the levels (that we will be able to integrate with the Box2D ...
1
vote
1answer
305 views

Correct way to update my physics frame rate

I've searched around here and Google and at last I looked at Fix your Timestep! article on the web which most of the people suggest. In according to that article I came up with an update method like ...
0
votes
3answers
715 views

Box2D body jitters when colliding with static body

I am developing a game where a body is moved within the scene using touch. The scene has a boundary wall made up of static rectangular bodies. When I move the object along the boundaries, on ...
0
votes
1answer
1k views

Error using Physics Body Editor for LibGDX

In my game, I've been trying to use the physics body editor for libgdx, but I kept on getting an error. So I thought there was probably something wrong with my code so I took the example off of the ...
2
votes
1answer
452 views

Camera scrolling and game boundaries

I am making a platformer game in JBox2D and LWJGL that has a scrolling camera, but I have hit a wall with the boundaries of the camera. Essentially what I have right now is a Box2D world that is ...
2
votes
1answer
351 views

How do I make my camera follow a Box2D object?

I'm implementing a camera in my game. It worked for regular objects, but I began using Box2D and obviously things changed a bit. I have a Body object that I want to draw at the center of the screen. ...
1
vote
0answers
266 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 ...
1
vote
1answer
200 views

Starter love2d physics program not working

I am starting out with my first love2d (using LöVE 0.8) physics program. I am just creating some ground/floor, a car body and attaching two wheels with revolute joints and setting the motors a-go. ...
1
vote
1answer
460 views

Is it a good idea to use box2d to control sprite movement in a 2D game?

I'm trying to use Box2D to control sprite movement.Some burning issues are these: 1.When I trying to move the sprite on a slope or a lean barrier. The sprite will move off the slope which is not what ...
4
votes
1answer
205 views

Is it possible to apply a texture inside a GL_LINE_LOOP?

I am creating a game using Box2D and OpenGL ES 1.1. I am taking the b2PolygonShape vertices and converting them into an OpenGL ES 1.1 GL_LINE_LOOP. The debugging view looks great, but now I want to ...
4
votes
1answer
660 views

C++ SFML Box2D - Somewhat confused when it comes to syncing phyisical body with a render body

While testing Box2D with SFML I encountered something which confuses me: The relation between physical body centroids and SFML's sprite origin. As an example I have a test class GameObject which is ...
1
vote
1answer
988 views

2D Destructible Terrain with Box2D / Cocos2D -> Image Tracing

Bear with me as this will be a rather lengthy post. For the last month I have been working on an open source Cocos2D, Box2D Destructible Terrain Engine. I have some questions regarding its ...
1
vote
0answers
244 views

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, ...
1
vote
1answer
155 views

Cocos2D: Box2D body that is movable by one type of object but not another

I'm in the process of creating a simple platform game using Cocos2D 2.0 and Box2D. I'm trying to create a kind of crate object that cannot be moved by the player, but that can be moved by an elephant ...
2
votes
1answer
467 views

Box2D: Asteroids-Like Spaceship Physics

I'm new to Box2D (JavaScript) (and the world of physics/mathematics) so I'm having a hard time working out the methods I need to use to make a spaceship act like it does in the classic arcade game ...
1
vote
1answer
888 views

Box2d contant speed before and after collision

I want to make my body fly at constant speed, how to make it fly at constant speed before and after collision? I set restitution of my body to 1.0 but after some direct and powerful collisions my ...
4
votes
1answer
499 views

Box2D Joints in entity components system

I search a way to have Box2D joints in an entity component system, here is what i found : 1) Having the joints in Box2D/Body component as parameters, we have a joint array with an ID by joint and ...
3
votes
0answers
134 views

How to make the Angry Birds “shot arch” dotted line? [duplicate]

I am making a game that includes 2D projectile flight paths like that of Angry Birds. Angry Birds employs the notion that a previous shot is shown with a dotted line "arch" showing the player where ...
3
votes
1answer
538 views

How to implement server side physics?

I am working on 2-player 2d sidescroller. How should I implement the physics on the server? Use one world for every game or use a big world in which I add every 2 player that start a game? I have ...
2
votes
1answer
253 views

Using Box2D for range detection?

I have two entities. One has a sword, one has a bow and arrow. When the bow entity is 100 units away, he needs to begin attacking. Likewise, when the sword entity is 10 units away, he needs to begin ...
-2
votes
1answer
115 views

Language & framework for fast prototyping Box2d problems [closed]

I am often in need of a fast prototype box2d scene where I can play with parameters. I work with AndEngine on Android which doesn't suit me for prototyping. It's good for the final game, but ...
-2
votes
1answer
673 views

How do I change gravity of box2d world after world is created?

I want to modify the world of box2d after creating it, namely to change the gravity vector. Is there a way to do this?