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Questions tagged [box2d]

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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LibGDX Box2dlights - Body Shadow Problem

While playing around with the box2dlights with libGDX, I have managed to get it all up and running, but have a problem with the shadow rendering. This is what I currently have atm: With the lighting ...
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2answers
90 views

How do I implement efficient collision avoidance in 100 enemies

I am developing a libgdx game. It is a top down shooter and I am trying to make a good AI. I have tried to implement A* from the AI library from libgdx and it works fine but when i have a lot of ...
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How to make sleeping bodies interact with sensors in box2d?

I am making a top-down multiplayer game using box2d. The map is much bigger than the player's screen. I want to send players only objects that they can see on their screens. I am doing this to prevent ...
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185 views

What is the physics behind a 2D gravity tunnel?

In Portal 2, there is a concept of an "excursion funnel", a beam of light that moves physical objects in a certain direction. Here is a link to a demonstration. I added a simple implementation that ...
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How to implement a camera for a TiledMap with SDL2 and Box2d?

I m writing a game engine using mainly SDL2 and box2D, I implemented TiledMap class that loads a tmx map and everything is fine it even support animation and objects that later will generate Box2D ...
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How to keep sprites in sync with non-box box2d polygon shapes

By non-box box2d polygon shapes, I mean polygon shapes that are made by specified vertices, instead of using the setAsBox method of box2d polygonshape class. I know this much: CycleShape and box ...
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How to make a motorcycle running on a vertical circular track(loop-da-loop) without falling down due to gravity?

I am currently developing a game, motorcycle type game. Of course, my map is not just made up of simple line or curve. For example: a vertical circular track in the map. i've seen most 2D motorcycle ...
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How do I set the gravity of a plane world

As you can see in the image, the character is set to move on a ground plane, however that causes an issue with Box2d's gravitational pull. The player can go sideways, upwards and downwards on the ...
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box2d get velocity with which the body collide

I need to know with which velocity an object collide to test if the body is destroyed. For example, if a vase collide and getLinearVelocity() > 10 the vase will ...
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2answers
142 views

Top-down conveyor belt with Box2D

I'm trying to code a conveyor belt for a project made with LibGDX and Box2D and I would like to make it like this one from Bomberman Land Touch. As you can see, the entities standing on it should be ...
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73 views

How can i collide two bodies without filtering(collision filtering)?

I have two bodies with fixtures. One is platform or ground and other is the player itself.I want to collide the player to the platform without bit filtering.How can i do that?I can see the rectangular ...
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Does destroying body also destroys the sprite?

Suppose a sprite is attached to a box2d body. And world.destroyBody(b); is getting called then the sprite also get destroyed or it stays there in memory. In my ...
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How to set a box2d body to follow a strict path

I'm making an infinite runner type game and I want one of my enemies (when it's created) to swoop down in a sort of U motion where it'll hit the player if they don't react quick enough once the enemy (...
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133 views

How to remove horizontal black bar at the bottom of the game screen in libgdx?

Here is the screenshot .Here is my Play constructor in Play class.
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Tuning physics for a “worms”-like game

I'm using LibGDX and Box2D for my physics but my characters bounce all over the place when moving and if there is a small slope in the terrain they launch off of it. I've tried tweaking settings but ...
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Box2d detect separated none blocking floor as blocking wall

I'm trying to make my character walk on walls, it all goes okay-ish currently until this situation. Here's an image to show you how the wall looks like https://www.dropbox.com/s/5oyn55qpzljlhnl/...
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What does linearDamping mean in Box2D?

If I set linearDamping on a body, it's velocity will be decreased slowly, until it stops. The documentation says, that the units are 1/time, which is unclear for me. If the velocity of a body is 10 m/...
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Is there a “Least Terrible Method” for sharing Entities over Network?

(Preface: Using C++, Box2D, and built UDP client and server classes that are reasonable efficient for a built-from-scratch game using client-server model.) This question is specifically in regards to ...
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126 views

Simulate wind affecting a boat using a 2D physics engine like Box2D or SpriteKit?

I'm looking for a way to simulate the forces created by wind and how it affects a boat. In a nutshell: if wind hits a boat (sailing yacht), the bow is aligning with the wind and if the wind is strong ...
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2answers
69 views

Why is the sprite so offset from the physics body?

I'm trying to make a sprite object that has physics, but once the game runs the physics body is drawn at an unknown offset from the sprite, which varies based on the size of the sprites texture. ...
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LibGdx TouchScreen Movement Logic with Box2D

I'm trying to implement some touch screen controllers to my game and i'm having a few issues :( i don't really understand what's the right way to do it, i can't figure out how to press simultaneously ...
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37 views

Box2D and OrthographicCamera working incorrectly

I'm trying to build a simple game where TileMapRenderer renders a labyrinth, a ball moves in it and camera follows it. I'm currently having the following bug: For some reason, the game renders the ...
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Box2d punch detection

So working on a 2d fighting game and wondering whats a good method for detecting punch collision. Ive got a few questions on how to implement the attack stuff. Im using box2d (and Libgdx) for the ...
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Box2D More Than 16 Categories

as I have got such a good answer on my other post I will ask this one too: Do you know a workaround or fix for the issue in the library box2d that you cannot add more than 16 categories? (I have read ...
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Drawing Explosions Respecting Walls

I am creating a tiled game (2D top down) and I created explosions working this way: The blue lines are walls, the white grid is accessable space. The red dot is the origin of the explosion with the ...
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1answer
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Box2D simulation running slower on lower FPS(even when the desired FPS is lower than the actual)

I´m playing around and trying to make myself an easy platformer using the Box2D physics, before that I was not using it and was using my own physics implementation(just simple movements with timestep)....
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libgdx draw/animate curve (tentacle) according to Box2D spring wavering

The horizontally placed Box2D spring is made of distantJoint connected bars, and can bend up and down just like airplane wing does when you flight (bigger amplitude ...
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Why does my rendering not correspond with my Box2D world?

I've decided to try to use the Box2D physics engine in my game, and as I started I'm facing weird behaviour. I've followed a video tutorial where we setup the Box2D world with world gravity, and then ...
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LIBGDX Let me know how to pause a game

I tried to make pause button. When users click Pause button on a screen, a window came out then, game is frozen until users press continue button in the window . my code is able to pop up window, ...
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2answers
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let me know how to save an integer for game stage level?

I am trying to make a game which there are many stages. For example, If users are done stage 3 of the game, and then turn off the game, they can play the game at stage 3 anytimes. simply, I tried ...
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217 views

libGDX, box2d, Ashley ECS - Collision Detection using Box2d does not work when using components with Ashley ECS

I've just recently learned of Ashley ECS while searching up tutorials on the libGDX wiki and I've been replacing many aspects of my code with the Ashley ECS components which has made life a lot easier,...
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fixed moving distance of the object box2d (libgdx)

Another problem befell me during the development. May be i will be skilled enough to help other after finishing this project. But now i have questions myself. Most games are made so that the ...
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Frame independent box2d object movement

In my game I use box2d objects and, as I understand it, you can move them only in two ways, SetLinearVelocity, and ApplyImpulse. I need to move the object 32 pixels in 1 turn. So I make a constant ...
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269 views

How can I generate vertex data from an SVG?

I am trying out the Phaser game engine, and am interested in making a vector graphics game (simple black and white like Asteroids), but I want to use vector graphics instead of raster PNGs. I was ...
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203 views

Unable to get Box2dlights to cast shadows

I'm trying to use box2dlights to add lighting to my game and I have everything working except I am unable to have shadows cast with my box2d bodies. I also have collision working using category/...
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1answer
53 views

How to make body flying

I am trying to make a body flying is there any way to change gravity or hold the circle levitating? Here is the code i'm using: ...
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1answer
68 views

Translating ChainShape to world coordinates according to touch drag input

I'm trying to draw a ChainShape according to touch screen coordinates, however the coordinates are slightly off from my touch coordinates. I translate the chain drawn on the screen to world ...
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1answer
61 views

How to destroy multiple bodies

In my game(2D game) I have these fireball objects. When I launch a fireball I want to destroy the object (because I'm not going to use it anymore). I tried deleting the fireballs, but, from what I can ...
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crashing generating fire-balls(bullets) with Box2D

I got crash, making fire-balls as bullets. I guess I should not use "private Array fireballs" in player class. it seems like when I add one more fire as index of 1 into the list, the first index ...
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1answer
266 views

LibGDX player movment

I'm working on a project in LibGDX. It's a 2d platform game; you can say it's like Super Mario. So this is how I move my player to the right: ...
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How to render texture into box2d objects from Tile Map? Libgdx

I have a problem, when i try to render textures. I read positions of gameObjects, for example coin and create box2d objects circle shape. I have wrote game logic and began make a graphic. But for some ...
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1answer
90 views

Object in Box2d doesn't sit perfectly on top of other object

I have a rectangle in my player class with the following properties ...
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1answer
159 views

Box2D - Constant Movement without ignoring Physics

I am developing a small game with LibGDX and Box2D. I want to move a body at a constant speed, lets say 2 m/s (meters per sec). The body should accelerate to that speed immediately when pressing the ...
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60 views

Fatal error… LIBGDX [duplicate]

I have an issue to launch fireball. when I launch fireball more than 10 swiftly, I got an error. especially, when my character becomes big which means to do redefine body.. I am still not sure why ...
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1answer
205 views

to remove body…in libgdx

I need to fix my destroyed fireball part. so, briefly, you can see there is condition, when fire ball takes 0.5 seconds, it will be destroyed, but the problem is that when I launch fireball more than ...
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1answer
161 views

error, how to remove BOX2D

I got an error, when I launch fireball too swiftly, I guess, my fireball does not really remove well. So that's why I got crush.. Can you guys check my update method, and please give me some idea? ...
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1answer
258 views

libGDX change map

I am struggling with changing map. Basically, when my character collides with the finish line, it should change to the next map. This is something like my simple code... Class A implements Screen ...
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1answer
50 views

Turn a spaceship at a max rate

Using the following to turn a spaceship in a C# FarseerPhysics simulation. var turnPower = _Inventory.EngineTurnPower * time; body.ApplyTorque(turnPower); If ...
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1answer
90 views

Box2d Javascript Disable Contact Between 2 Objects

I want two objects, when collided, to not effect each other in velocity or force. I have looked up guides and they say to change the PreSolve so that b2Contact.SetEnabled is false... which in code is ...
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Substepping concern for collision triggers

I've read "Fix your Timestep" article by Glenn Fiedler and convienced myself I should divide timing evenly on physics part. So I have did as follows: ...