Tagged Questions

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

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0
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0answers
45 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
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1answer
86 views

Box2d stopping the movement of an object

I am in the process of making a game and I need an object to move only when the buttons are pressed. I have a method that begins the movement, and so far I am ending the movement of an object by ...
2
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3answers
119 views

Box2dWeb: setting velocity of bodies using events

I would like to move a kinematic box by pressing the down arrow. As is noted by the console logs, the keydown actually does change the box's velocity... but for reasons beyond my grasp it still ...
0
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0answers
47 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 ...
9
votes
1answer
549 views

How do I make a curved surface out of rectangular blocks?

For a Peggle-like game, I want to make blocks that follow a curve, like this: The blocks would then disappear as the ball hits them. I managed to draw some horizontally, but I'm having trouble ...
4
votes
1answer
240 views

How do I simulate a trampoline?

I'm quite new to game development. I was pretty impressed with the elastic effect I saw in this flash game when the ball hits the trampolines and I'm wondering how to recreate it. I've done some ...
1
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0answers
54 views

Box2D setGravity() in Andengine?

Im currently using the Andengine GLES20 branch. I know that the new Box2D method setGravity() isn't implemented yet. Has anyone managed yet to get it to work with Andengine or to write a method ...
0
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0answers
40 views

Box2D Joints Disconnect

I'm trying to make a soft body physics system using rigid bodies in a circle. I'm having a problem where my joints only connect to one of the bodies, and seems to disconnect from the others. I think ...
0
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1answer
92 views

Trying to make sprite float up and down [closed]

Using LibGDX + Box2D and my understanding of the answer posted from this question: Here I apply the following impulse: // modify sprite's Box2d Body object int a = 8; // amplitude int f = 1; // ...
2
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2answers
149 views

How do I create a horizontally centered “gravity line”?

Here's my ideal scenario: A game object (in blue) can change its horizontal velocity, but it will be pulled back by gravity (dotted gray arrows) toward a central vertical line (in red). How can I ...
0
votes
1answer
137 views

How could I control an air hockey 's AI paddle?

I am making an air hockey game on Android with Box2D and libgdx. For the manual control, I just use the MouseJoint and it works perfectly. However, for the AI control, there is a problem: I've made a ...
0
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0answers
578 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 ...
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vote
2answers
833 views

Box2D Libgdx removing bodies in case of simultaneous collisions

I am making a clone for the BreakOut game. I'm using Box2D and Libgdx for it. In the game, one scenario is that there could be 2-3 balls at one time. Now the problem occurs when 2 or more balls ...
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0answers
54 views

Box2d - Allow object to pass but still report collision [duplicate]

I am creating a laser which is a dynamic body with its own collision filtering. I want it to not collide, as it does not currently but I want it to still report the collision or when the two overlap. ...
1
vote
2answers
124 views

How can I find all connected objects of the same type recursively?

In my game, when a user selects an object of some type, I'd like to search for all other objects of the same type that are connected to that first one. For example, if the user selects a object of ...
1
vote
1answer
179 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
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0answers
252 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 ...
0
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1answer
2k views

How to set a body to a specific position using Andengine

I'm developing a game with a single player and multiplayer mode. Lets say I have walls (static bodies), vehicles (dynamic bodies) and bullets (dynamic bodies). It works fine to control my own vehicle ...
0
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2answers
114 views

Floating point precision issue with Box2D

I'm using Box2D and I am putting edge tiles as b2Bodies so that the tile world can have physics: The problem is that there are 3 b2_kinematic bodies under the player right beside each other. Every ...
0
votes
1answer
120 views

Box2D + Citrus Engine - Proper Pong Paddles

I am creating a pong clone for my first Citrus Engine project using Box2D. I've tried two types of paddles, both do not fully work. 1) Paddle is a dynamic body with a restitution of 1.0 and friction ...
0
votes
3answers
217 views

How do I prevent other dynamic bodies from affecting the player's velocity with Box2D?

I'm working on my player object for my game. PhysicsBodyDef def; def.fixedRotation = true; def.density = 1.0f; def.position = Vec2(200.0f, 200.0f); def.isDynamic = true; def.size = ...
2
votes
1answer
189 views

Using Box2D / Physics with Tiles?

Here is my issue. I currently have Box2D setup and working. But, it works with my Entity system. So I can create static objects and dynamic moving ones, and they simulate fine. However, my world is ...
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2answers
152 views

How can I get the force of a collision in Love2D?

Is it possible to get the force of a collision between two objects in Love2D/Box2D? If so, how?
0
votes
1answer
484 views

Communication between Box2D and libGDX Stage (Scene2D) running in separate threads

I'm making a physics based 2D game using libGDX and Box2D. I want to move the execution of the simulation out of render thread. I use immutable messages and the BlockingQueue to pass the information ...
0
votes
1answer
115 views

How to make box2d bodies block each other but not push each other?

I want to use box2D to create a movement system for an RTS game. How can I make bodies block the movement of other bodies while preventing these bodies from pushing each other?
0
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1answer
73 views

Create body on a sprite (box2D)

I'm quite experimented in objective C, but now i'm tried cocos2D and his features. I need to add a body on a spritesheet (if possible on a classic 'UIImageView'), in order to detect collisions after. ...
3
votes
2answers
3k views

How can I convert a tilemap to a Box2D world?

I want to use Box2D physics and lighting with a .tmx map. How can I "convert" a tilemap to Box2D world? My basic idea is to go through the tiles on the map and create an object for them in Box2D. I'm ...
3
votes
0answers
90 views

How can I smoothly rotate a joint to an angle? [duplicate]

I would like to set the speed of my Box2D revolute joint on every update such that it rotates to a desired angle and stops. It should ramp down as its angle approaches the desired angle. My first ...
1
vote
1answer
91 views

Farseer - Difference between Position, GetLocalVector, and GetWorldVector

I have used Box2D extensively, and am used to just calling body.GetPosition(). But Farseer does not have this. Instead it has a property Position, as well as methods GetLocalVector and GetWorldVector. ...
2
votes
1answer
307 views

libgdx default saving mechanism for box2d world

I want to save my game in libgdx, and I have no problem using Kryo to save everything, except the box2d Worlds and the RayHandlers from box2dlights - these are not Serializable and do not have default ...
0
votes
1answer
44 views

Check every body's position and delete or not (box2d performance specific)

I have a simple game with a platform (a ground that's not infinitely long). During the game I have about 10-30 balls on average that'll fall off the platform. There's gravity so I think they'll keep ...
0
votes
1answer
131 views

How to spawn an object on collision in box2d + love2d?

I'm trying spawn collidable debris from a ship when it explodes in love2d/box2d, however, World:isLocked() is true when collision callbacks are called: This will return true inside the callbacks ...
8
votes
3answers
381 views

Make fast thing look slow (Box2D)

I'm working on a game that you control a trebuchet to throw balls to the opponent. It's like a game called 'Medieval Siege'. When the trebuchet is swinging its arm, player need to seize the best ...
-1
votes
1answer
115 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
vote
2answers
363 views

How to find collision detection side between two objects?

I am using box2D and I have two objects, one is bouncy ball and the other one is block. I'd like to find which side of the block is collided with, so I can only make the ball bounce when it hits the ...
0
votes
0answers
34 views

2D collision beetween a sprite and an array of sprites [duplicate]

I am creating a simple Android jumper (think Doodle Jump or Abduction) using libGDX so I can get started in game programming. My problem is that I need to figure out a way to check for collision ...
1
vote
1answer
236 views

Syncing world in a multiplayer

I have been working on a client-server architecture for my multiplayer game. The server is used for communication between Clients. There is no cheat control because I trusting all clients :) I don't ...
0
votes
1answer
37 views

Using texture() in combination with JBox2D

I'm getting some trouble using the texture() method inside beginShape()/endShape() clause. In the display()-method of my class TowerElement (a bar which is DYNAMIC), I draw the object like ...
1
vote
1answer
93 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 ...
0
votes
1answer
110 views

Physics don't apply on a unique body AndEngine

I am developing a game in AndEngine. So far I managed to create everything I wanted for my sprite that was connected to a BoxBody. I was rotating it, moving it, everything was great. I wanted my ...
5
votes
2answers
369 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
63 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
164 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
418 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
911 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
520 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
114 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
631 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
82 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 ...
3
votes
3answers
988 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) ...