Tagged Questions

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

learn more… | top users | synonyms

0
votes
1answer
20 views

Explain the difference between extrapolation and interpolation

http://www.unagames.com/blog/daniele/2010/06/fixed-time-step-implementation-box2d here there are two algorithms of smoothing in case of fixed time step physics simulation. I don't understand the ...
0
votes
1answer
28 views

Box2D pixel to meter conversion

I have a game that was written in pixels and now I want to change it to meters like(box2D do). How I need to do that. I have wached a lot of tutorials and all they have some SCALING FACTOR but when I ...
1
vote
0answers
49 views

Should I use Box2D for collision-detection only (not simulating physics)?

I'm using Box2D only to check collisions and for no physical simulation. I create bodies (and shapes for them) and use my own code to move them, by setting their velocities and positions every frame. ...
0
votes
0answers
44 views

How do I implement one-way platforms in AndEngine and Box2D? [on hold]

I'm trying to figure out one-way platforms for my doodle jump clone on AndEngine. This post helped me a lot. I've implemented similar code on my own. Platforms should be solid only when my player's ...
0
votes
0answers
37 views

Make a smooth curved terrain from chain shape [on hold]

what have i tried: Vector2[] vs = new Vector2[6]; vs[0] = (new Vector2(-50, 7.3f)); vs[1] = (new Vector2(-18, 7.3f)); vs[2] = (new Vector2(-10, 2)); vs[3] = (new Vector2(-5, 4)); vs[4] = (new ...
0
votes
1answer
23 views

box2d ChainShape into curved line

i need to draw a curved line , i searched the internet and found nothing , maybe someone with knowlegde on the subject can help me with a link , i used chain shape and did this , and i don't know ...
0
votes
0answers
19 views

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 ...
0
votes
0answers
45 views

What is the best framework for 2d side scrolling game (with physics support like box2d) [closed]

I have previous knowledge in Libgdx since I developed a game in it. So the learning curve will be a bit less. Still, if there is a better platform for side scroller (preferably Java), then I would ...
0
votes
0answers
55 views

simple but powerful 2D physics engine c++ [closed]

The two big 2D physics engines out there are Box2D and Chipmunk, which can create a lot of complicated collisions. but the only collisions I need to do are grid-aligned AABB collisions, so I just ...
0
votes
1answer
10 views

Box2dWeb: must fixtures be destroyed explicitly when destroying the body?

I use b2WorldObj.DestroyBody(bodyObj) to destroy the body when it is not needed anymore. The body has one fixture attached to it. Do I need to destroy the fixture before destroying the body? or ...
0
votes
1answer
36 views

Throwing a bomb LibGDX Box2D

I am trying to create game where somenone throw a bomb. I am wondering how I can have an bomb react in a way that is represented by the following picture : Is there are any tools in Box2D that can ...
0
votes
0answers
19 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
29 views

web based networked game physics efficiency

I am writing a web based game, using websockets. its pretty simple, two players shooting at each other with bullets that have acceleration from a starting point at an angle. The client side ...
0
votes
0answers
16 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 ...
0
votes
1answer
26 views

Box2D pixels to meters , LibGDX

I am confused . what shall I set the orthographic camera viewport in libGDX when I use box2d , in one tutorial I saw that he divided his viewport numbers to 32 because 1meter =32 pixel , but I think ...
0
votes
1answer
72 views

How to render a vertex buffer in DirectX11 C++ (specifically with box2d's b2Draw)

I have all the DirectX11 devices etc setup and working with DirectXTK's SpriteBatch and currently attempting to implement a b2Draw class to draw my box2d physics worlds. I have little idea on how to ...
1
vote
0answers
41 views

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 ...
2
votes
0answers
52 views

Box2d C++ x velocity slowing for no apparent reason

I'm making a 2d platformer in C++, using Box2d for physics and sfml for rendering, I want the player character to move with a constant velocity in the x direction, and to jump when the spacebar is ...
0
votes
1answer
47 views

Box2D Body creation causing performance issues

I have at max 10 dynamic bodies in my world at any time. they are created at random and fired up from below they screen. when a new body is being created, the fps falls from 59 - 61 to about 35- 40 ...
0
votes
1answer
11 views

Box2d polygon skin

In manual is see: Polygons inherit a radius from b2Shape. The radius creates a skin around the polygon. The skin is used in stacking scenarios to keep polygons slightly separated. This allows ...
0
votes
1answer
29 views

How to make an object in box2d have constant velocity even after collision? [duplicate]

I have iOS game where I have a bouncing character. Everything is being handled by box2d. The problem is when the character hits a wall of another character it's velocity changes, but I don't want ...
3
votes
2answers
156 views

Why is Euler integration sometimes preferred over RK4 even if RK4 is more accurate? [closed]

Some high quality engines such as Box2d uses the Simplistic Euler integrator instead for RK4 when Eumplectic Euler commits a global error of the order of Δt whereas, RK4 has Δtˆ4 error? RK4 is not ...
0
votes
1answer
46 views

Box2D recommended step, velocity and position iterations

Here in this article there is a nice explanation that velocity iterations and position iterations settings affect the way bodies will react when they collide, and step affects on speed and how gravity ...
0
votes
0answers
46 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 ...
1
vote
0answers
30 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 ...
3
votes
0answers
170 views

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 ...
0
votes
1answer
25 views

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 ...
0
votes
0answers
40 views

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 = ...
0
votes
1answer
64 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 ...
0
votes
0answers
26 views

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; ...
0
votes
1answer
73 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 ...
0
votes
0answers
15 views

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 ...
0
votes
0answers
27 views

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 ...
1
vote
1answer
25 views

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.
1
vote
1answer
25 views

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 ...
0
votes
1answer
46 views

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 ...
0
votes
0answers
93 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 ...
-1
votes
1answer
100 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 ...
0
votes
0answers
53 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 ...
0
votes
1answer
53 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 ...
1
vote
2answers
127 views

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 ...
0
votes
1answer
52 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?
2
votes
3answers
93 views

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 ...
0
votes
0answers
25 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
22 views

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 = ...
0
votes
0answers
99 views

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 ...
0
votes
1answer
61 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 ...
0
votes
0answers
48 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 ...
1
vote
1answer
196 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 ...
0
votes
1answer
118 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 ...