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Questions tagged [bullet-physics]

Bullet is a professional, free 3D Game Multiphysics Library that provides state of the art collision detection, soft body and rigid body dynamics.

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rayTest for cutted by stencil objects

I have red rectangle based on which I am cutting (using opengl stencil) all of the green rectangles, like shown in the following screenshots a) before cut b) after cut When I run rayTest(bullet ...
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1answer
18 views

Detect collision with bullet physics, to make a character controller

I inherited from btCollisionWorld::ContactResultCallback but I really have no idea how to use this virtual function: ...
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23 views

btRigidBody world transform and scale issue

When I create a collision shape for rigid body (in this case box) I use vertices positions and scale from the opengl matrix, the code looks this way: ...
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1answer
30 views

Body inside other body after collision

I'm using bullet to create a 2D topdown game. In my physics proof of concept, I can walk around and push a box. However, if I walk too fast the character goes through the box, instead of colliding ...
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How to use Bullet ghost objects in libGDX?

So I went and did some research on how to get Bullet's ghost objects work in libGDX. There was nothing about the Java port of it, so I tried to translate some of the C++ code I found into Java. ...
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1answer
30 views

How to deal with standing/walking models?

I'm developing a game using bullet for the physics logic, but rendering using my own isometric algorithm (sprites). I'm currently dealing with the issue of how the physics object of the player would ...
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2answers
48 views

How to access coordinates of objects in bullet physics (libGDX)?

I need to access the x, y and z coordinates of a bullet physics object. I'm assuming this is done via the transform matrix, but I have no idea which values mean what. There doesn't seem to be any ...
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1answer
73 views

Bullet Spray RNG

So I have a Nuclear-Throne like weapon system in my game, and I'm working on bullet spray. Originally, there was equal odds that the bullet sprayed at any angle within the spray range. That felt ...
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91 views

How do I create a HeightField in pybullet?

I've been looking for documentation on PyBullet, the python implementation of Bullet, but I haven't yet found a way to implement the btHeightfieldTerrainShape collision object, which I need to make, ...
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77 views

Problem about simulating rigid body rotation with bullet physics engine

I want to simulate an object imposed by a torque T={1,1,1} with reference to the world frame. The mass of the object is 1Kg, and its diagonal elements of inertia tensor is {2, 1, 1}. However bullet2.7 ...
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1answer
70 views

Bullet Physics too many rigid bodies framerate drops

I have a question regarding rigid bodies in bullet physics. At the moment I have low-poly asteroids, which I create a convex Hull shape. Then I add a motion state and give them a linear velocity. ...
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1answer
21 views

Having trouble with btGeometryUtil::isPointInsidePlanes

I'm in the process of parsing a BSP file to create btConvexHullShape objects for each brush. I've seen a few examples of how to do this on Github and they all use the getVerticesFromPlaneEquations ...
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128 views

Handling character with world object collision in libgdx and bullet

I am using libgdx and bullet for my 3d mmo project. I have been able to detect collisions using a collision world with collision objects. This was working fine for things like detecting players ...
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1answer
46 views

Eliminate 0.25 unit 'force fields' around Bullet Physics soft bodies

When I create soft body assemblies in Bullet Physics they will fall under gravity and then float about 0.25 units above a ground plane rigid body, and other rigid bodies all appear to push and ...
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1answer
54 views

Get GameObject which instantiated me in Unity

How can I get a GameObject from another GameObject? If I know, that the GameObject I want to get instantiated(using function Instantite()) the GameObject from which I want to get it. If there is no ...
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25 views

Interacting rigidbodies between two physics worlds/instances

I'll be posting my first question here. It's a hard one! But maybe you know a simple solution :) I'm trying to make a multiplayer game using bullet physics. I came to a lot of problems but now there ...
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1answer
2k views

Rifle bullets/projectiles in Unity, raycasting or rigidbody?

Hello again gamedevers :) I'm trying to create a fairly simple FPS shooter game. Im using a Rigidbody FPS Controller prefab from ...
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0answers
141 views

Bullet Physics Scaling rotational part of 6DoF Spring Damper

I am currently trying to scale up my setup (consisting of two rigid bodies connected by a btGeneric6DofSpring2Constraint) to fall within the suggested dimensions for a concise simulation. In order to ...
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1answer
601 views

Build a convex hull from a given mesh in Bullet

According to this tutorial, a convex hull is the most accurate shape one can build from a mesh? I have two questions regarding this: How do I build a convex hull from a given, complex mesh in Bullet? ...
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1answer
374 views

Graphical mesh lags behind collision shape in BulletPhysics debug drawing

In Bullet Physics when I debug draw physics world the graphical mesh lags behind the collsion shape. ...
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41 views

I have two problem for install wrapper OgreBullet in Ubuntu

I need to use physics bullet, but is more easy use with wrapper ogrebullet, then I need to install Ogrebullet. Please, Help me! ...
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1answer
209 views

Bullet: btCollisionWorld::contactTest doesn't work

I added some boxes in a collision world, then use btCollisionWorld::contactTest to test if any box contact with a given sphere. Below is the code: ...
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2answers
229 views

Best practice for RTS accuracy/aim

As I'm developing a RTS game set during the Napoleonic Campaign, I've got a question about the best method to implement 'bad aim' for the AI, as the accuracy of muskets were quite terrible back then. ...
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3answers
648 views

Calculate damage values from bullet velocity and size

I'm trying to make a top-down game using javascript and Pixi which involves multiple different guns. Instead of giving each gun an individual damage value, I wanted to calculate the damage by the ...
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2answers
506 views

Rigid body physics resolution causing never ending bouncing and jittering

I'm trying to make a fairly simple, impulse based rigid body simulator as part of a Uni assignment. I'm using bullet physics to perform collision detection, and my own code to perform collision ...
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1answer
93 views

Is it possible to find the child body involved in a collision of a compound shape?

I am noob at using bullet physics. I am using it for collison detection and I want to create a compound body to represent a ship. However, in my game I need to know which part of the ship was hit. ...
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2answers
414 views

Make a bullet shape around model in libgdx

How do I make a btBoxShape around a Model or ModelInstance in Libgdx? This is my code: ...
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1answer
101 views

Workflow for non human ragdolls

So I want to make automatic ragdoll generation system for all my enemies in my game, the assets are already made and have been paid for a while ago so I can't really ask the artist to change anything ...
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1answer
314 views

Passing heightmap data to btHeightfieldTerrainShape constructor

I was searching for a couple of hours, but I didn't find final solution, after trying many ways. I'm trying to get heightmap heights data, and pass it to btHeightfieldTerrainShape. Let's say my ...
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0answers
235 views

Retreive 3d World Map coordinates from touch/click input with LIBGDX?

Problem: I am trying to create an RTS style interaction. I want to be able to click on the map and have characters move to the click location. I haven't been able to figure this out, even after ...
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1answer
237 views

How to create shockwave of objects in other shapes than circle?

Basically, I'm making a bullethell / I wanna be the guy inspired game for where I'm currently creating different methods of spawning bullets into the game. One of the few methods I've created is ...
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0answers
278 views

Soft body plasticity using Bullet Physics

I made this post on the Bullet forum(link), but the forum is slow so I'm just copying the text from there. Hello, I'm currently working on a game and I want to make certain surfaces of the game ...
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1answer
82 views

Bullet Physics Applying Torques Effects not noticeable

I am applying torques to a rag doll in order to make it move/walk. For some reason, I am unable to view any effects when I use a call to rigidbody to apply torques even though these torques are ...
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1answer
206 views

Bullet: No Bouncing off the walls

I'm using Bullet Physics for Collision Detection in a first person game. The collision basically work fine, I cannot walk through objects. But if I walk against the wall and release the key I get ...
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1answer
201 views

Bullet: Apply any Transformation to RigidBody?

I'm using Bullet for CollisionDetection. I load a scene from a Collada-File using Assimp. Let's say I want to give every object in the scene a RigidBody with a box as CollisionShape. Right now I first ...
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2answers
447 views

Gravity too weak

I am using Bullet Physics and the gravity in my world seems to be too weak. This means that items fall too slowly and general values don't make as much sense as they should. While I know that "...
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0answers
59 views

JBullet is acting weird, what is causing these 'floating' rigidbodies?

I've been working on a 3D game engine in Java for a school project. The game engine had scenes containing game objects, these game objects contain components defining the behavior of each object. I'm ...
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1answer
228 views

BulletPhysics ship rotation

First of all, I'm a beginner in game physics, and I think this is a relatively easy problem that I'm not grasping. Short Version: I have a box(representing a ship on water) going forward with a ...
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4answers
891 views

Should the bullet trajectory calculated by server or by client? [duplicate]

In a FPS game like Battlefield or Arma, when playing online, should the bullet trajectory be calculated by the server or by the client?
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1answer
1k views

Bullet Physics: Difference between Motion State and World Transform

In Bullet Physics, when I create a new btRigidBody, one of the parameters passed to the constructor is the btMotionState, which defines the initial pose of the body. However, if I then later want to ...
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0answers
440 views

Bullet Physics: Applying a force at the point of collision

Suppose I want to simulate some kind of gripper with two "fingers" (such as pair of pliers, or two-fingered robot hand), picking up an object from the ground. Both the gripper and the object are ...
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1answer
640 views

Bullet Physics Collision is Not Detected

I have created two btConvexTriangleMeshShape objects. One is a cube of size (0.1 x 0.1 x 0.1), and the other is is a plane of ...
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1answer
1k views

Why do Physics Engines use collision margins?

When using a physics engine in a game (such as Bullet), you usually need to define a collision margin for each object. I'm a beginner to game development, and I don't understand the purpose of a ...
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1answer
1k views

how to set in vector float x y coordinates [closed]

i am use eclipse java android i am try to projectile trajectory in my game like angry birds example here http://blog.gemserk.com/2012/07/03/drawing-a-projectile-trajectory-like-angry-birds-using-...
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1answer
501 views

Bullet Physics / OpenGL Meshes Not Colliding

This is for a school project, and I'm having a bit of trouble with Bullet acting strangely. I have an OpenGL project with Bullet Physics library working with Assimp model loaders and Magick++ ...
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1answer
3k views

Is restitution the wrong value, to make bouncing objects?

I have been experimenting with Bullet. Specifically I was modifying the Hello World tutorial, to make the ball bouncing. The first thing I noticed is, that I need to set both the restitution of the ...
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0answers
731 views

Java 3D collision detection with JBullet

So I have spent a long time trying to work on a collision detection system from scratch for own game engine and came up fruitless due to lack of time. Finally I decided to try to use Jbullet to try to ...
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1answer
56 views

Bullet Physic: Stack transformations on body after adding

How can I stack multiple transformations on a body? I mean... Rotate, translate and then rotate again? If I understood, a transformation on a rigid body can be made like this: ...
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1answer
190 views

issue with ray/physics collision detection

All, I am trying to pick object using ray collision and bullet physics I am initializing my projection and view matrix only once, here is the code ...
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0answers
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Bullet btGImpactCollisionAlgorithm

I have a question about Bullet and in particular GImpact. When, the collisiontestpair(a, b) is called where GImpact pair check algo will be called on the btGImpactMeshShape, does it do a AABB tree ...