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

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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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2answers
59 views

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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1answer
315 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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0answers
77 views

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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1answer
94 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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102 views

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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1answer
185 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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1answer
562 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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1answer
341 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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1answer
173 views

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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2answers
157 views

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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2answers
2k 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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1answer
54 views

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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1answer
201 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 ...
3
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1answer
490 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 ...
2
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1answer
171 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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1answer
192 views

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 ...
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1answer
796 views

How to rotate an image around its own center in AndEngine?

I'm beginner in Android programming with Andengine framework. And my question: How to rotate an image around its own center in AndEngine? I use Body and AnimatedSprite. Update This is my code: ...
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138 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 ...
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1answer
75 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 ...
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1answer
80 views

Preventing rapid inversions of boolean on Collision detection

I know this is both a strange question and a stupid question. But this is an issue I have dealt with in every single game I've made, and I have yet but to find a solution. I can't be the only one ...
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1answer
113 views

Player doesn't jumps in Box2D implementation [closed]

Well, i'm trying to learn andEngine. I was able to successfully implement the move functionality for the player. Now, i'm trying to make the player jump using Box2D. I referred few online tutorials to ...
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1answer
72 views

Is there any reasons to make sprites and bodies line up?

So in LibGDX the Sprite objects position is where it's 0,0 mark is in the word. In Box2D a a bodies position is in it's center. So to line these up when you update the sprites position with the ...
2
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1answer
186 views

How do I dynamically set a WheelJoint's anchor points?

I've created a car in RUBE and imported it into my game. The game has a tuning menu, allowing the ride height of the car to be adjusted with a slider. I can't work out how to change the position of ...
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63 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 ...
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1answer
64 views

SVG—Adding fire to the roket

as you might expect, I have got a game in development, including a main character—fortunately… This character is on the one hand represented by a bunch of Box2D bodies and on the other hand, ...
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2answers
155 views

Box2D—how make character tilt

I have got a floating character, which should be a robot like thing, floating over the ground, whereby I am using the »hovercar« effect described here. Zhe Image below outlines the basic setup of the ...
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2answers
2k views

How to get width and height from a body in box2d?

I am working on a game in Libgdx framework. I have to get width and height from a body in box2d. is their any way to get width an d height from a body in box2d??
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1answer
2k views

Movement and rotation of bodies in top down game

We are developing a 2D top down game with libgdx using the included box2d as physics engine. We don't want our bodies to accelerate but to instantly move with the wanted velocity. The bodies are ...
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1answer
800 views

Scrolling with SDL2 & Box2d - My Camera isn't keeping up with my player

I'm trying to get a game on the google play store before I'm 40 (long held dream to publish a game since the days of the speccy), I have just over a month to go so it's not looking good! Foolishly I ...
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1answer
159 views

Box2D: Adjusting character position for side-scrolling

In my side-scroller I would like to give the illusion of the character walking forward while his sprite is actually being held in place. If he walks near the edge of the screen, I would like to adjust ...
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2answers
417 views

How can I simulate a floating character in Box2D?

I am creating a jump'n'run game using the Box2D physics engine. The main character should be a robot like creature without legs, floating over the ground powered by a jet engine. The motion should ...
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1answer
59 views

Why can't I swap fixtures on collision in Box2D?

I'm trying to swap the fixtures associated with a body after colliding with a specific obstacle. I can listen to the collision event by extending b2ContactListener. I tested it with a trace and it's ...
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1answer
155 views

How do physics engines like Box2D detect and respond to collisions between arbitrary polygons?

I've always wondered how collision detection like this was achieved, and I've always wondered what the response would be. Do they perform line-line intersection tests for each line making up the two ...
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1answer
2k views

Maintaining velocity of free fall body using Box2D in libGDX

I want to maintain the speed of a free-falling Box2D body using LibGDX. I'd like the vertical velocity increase with the level. I've applied a linear impulse and velocity actually increases like this: ...
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3answers
574 views

How do I change the relative origins of a Box2D World and a TiledMap in Libgdx?

I'm playing around with Box2D and TiledMaps and I've come across this minor annoyance. As you can see, both Box2D and TiledMap render at the center of the screen. This forces me to compensate by ...
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1answer
474 views

LibGDX - Box2D: Realistic Light and Layers

I'm having some problems with my current game. Short description: It's a 2D game where you have to avoid the lights or you lose HP. My problem is the following one: Here is the rendering process: ...
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146 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 ...
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84 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 ...
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1answer
113 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
198 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 ...
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0answers
63 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 ...
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1answer
775 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
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1answer
293 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 ...
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1answer
94 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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1answer
108 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; // ...
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2answers
156 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 ...
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1answer
191 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 ...
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872 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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2answers
1k 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 ...