# 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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### Solving for radius and acceleration in spherical motion

I'm trying to solve a spherical motion problem which requires that I use applyForce and applyTorque methods in Javascript's Physijs engine (bullet3 transipiled with emscripten) I have peripheral ...
59 views

### Why does OnTriggerEnter2D/OnCollisionEnter2D work when there is no other collider object opposite?

my bullet: There is a Box collider (checked "is Trigger") It has Rigidbody2D (Gravity = 0, freeze rotation Z) https://imgur.com/T4j1QoO I added the "OnTriggerEnter2D" function ...
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263 views

### Raycasting in GameMaker Studio 2 to implement hitscan weapons?

I'm working on a 2D top-down shooter game in GameMaker Studio 2, featuring different weapons and obstacles all around the levels. Since I don't need a high degree of simulation, I'm implementing ...
• 3,904
41 views

### How to detect all vertices within collision Area?

Using collision detection algorithms such as MPR (Minkowski Portal Refinement), GJK (Gilbert–Johnson–Keerthi distance algorithm), you can calculate the penetration depth in the collision. For 2 mesh ...
• 101
1 vote
233 views

### Simulation step size in a physics engine

I am trying to integrate a physics engine (Bullet) into my game engine, but I immediately found that I do not know how big should I make the simulation step. I think of 2 options: Use a fixed step ...
1 vote
366 views

### How to move a player on a sphere surface using Ammo.js and Three,js

I am moving a rigidbody (the character) on the surface of a sphere, like what is described here. I am facing the following issue that I am having hard time to solve: After moving the character, it ...
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### LibGDX program crashing on on StepSimulation call

I am trying to add a Character Controller to a Discrete Dynamics World in Bullet via the LibGDX wrapper and everything seems to work, but when I attempt to update the world via the StepSimulation ...
60 views

### How to create soft tires like in Spintires?

Here is an screenshot of a deformed tire in the game Spintires. I would like to achieve a similar effect in my game I'm using Bullet as the physics library, if that matters.
1 vote
241 views

### PyBullet & OpenGL - Rotations are reversed in OpenGL [closed]

Project description: I am writing a basic game engine to help with my PhD topic on multi-agent learning. I am using PyBullet as the backend physics engine and OpenGL for visual display. I have OpenGL ...
1 vote
58 views

### Subtract a circle on a rectangle - OpenGL

I am writing a game using GLFW, GLEW, GLM and Bullet3 in C++. Its a Maze with holes. I am doing the floor with rectangles (wich is 2 GL_TRIANGLES). I want to make some woles (circles), to the ball ...
81 views

### Can't get basic example working with Bullet 3 (haxebullet port)

Example of my code: ...
120 views

### Bullet Physics Invalid Pointer on Free

I'm writing a game engine in C++ with Irrlicht and Bullet Physics. All of my Irrlicht code works perfectly, but upon creating Bullet Physics objects with new, and later freeing them, my program throws ...
257 views

### Bullet Physics Step Simulation Crash when maxSubSteps is not 0

I am using Bullet physics along with Irrlicht. My program consistently crashes when maxSubSteps is not set to zero when calling ...
1 vote
47 views

### Real-time 3D Scene-reconstruction into Physics Engine

I am trying to create a game where the user scans the room using RGBD camera and reconstructs 3D scene. This scene would be integrated into physics engine, after an object recognition algorithm tells ...
1 vote
90 views

### Bullet Physics stops detecting collision after a few steps

Let me start off by saying that the usage of Bullet here is slightly unconventional. I'm writing a server emulator for a game, and the server is only keeping track of the triggers, players and enemies....
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### Angle between character and mouse, and giving bullets velocity in the correct direction

I've been trying to work for a few days, on a little weapon system where you can aim with your mouse and shoot bullets in the direction you're aiming. This is all in 2D to be clear. Right now, I can ...
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219 views

### Soft Body rendering from OBJ model

As part of my master thesis I have to do an softbody simulation. I 'm using Bullet Physics engine. I'm trying to render softbody, create from Meshes, with Shaders in OpenGL but the object doesnt ...
1 vote
41 views

### Bullet Physics ignore collision from bottom

I'm currently using BulletSharp a wrapper for Bullet physics. I'm using Bullet Physics for a 2D project. Many platform games allow the player to pass through a platform as they jump upwards, and then ...
1 vote
302 views

### Bullet physics convex hull center of mass

I am trying to make a convex hull collider for bullet physics. I am using BulletSharp.CompoundShape and BulletSharp.ConvexHullShape. This is model of a chair in unity with rigidbody and convex mesh ...
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259 views

### Bullet Physics DebugDraw Unexpected Results

I'm integrating Bullet Physics into my project for collision detection and have just gotten some debug draw functionality to work. However, the results are not what I'm expecting. I have tried to draw ...
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1 vote
218 views

### Bullet Physics StepSimulation really slow when smaller TriangleMeshShape is inside bigger BoxShape

I observed that bullet physics StepSimulation is very very slow when a rigidbody with a TriangleMeshShape is fully inside a rigidbody with a simple BoxShape. I noticed that when I move the ...
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1 vote
147 views

### Should your world map have it's own collision object?

I am attempting to understand collision detection at the moment. I have seen many examples of a simple flat plane with boxes or cubes which move around on the plane and react when the touch each other ...
• 171
135 views

### Solve Constraints with linear factor of 0 in Bullet Physics

In my code I need to set the linear factor for velocity to 0 (sometimes). For example, game->rigidBody->setLinearFactor(btVector3(0, 0, 0)); When this is done,...
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1 vote
104 views

### btBvhTriangleMeshShape useQuantizedAabbCompression Crash

I use btBvhTriangleMeshShape for static world collision. Generally this works fine, but recently I have encountered situations where the construction of btBvhTriangleMeshShape would crash. In debug ...
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1 vote
64 views

### Handling strange physics behaviour while sliding between coplanar surfaces

We've got a character setup based around manually resolving collisions, and we're using bullet to do so. Our characters have a kinematic rigidbody to push things around, but their movement and ...
1 vote
664 views

### Bullet Physics Integration - direct movement of rigid bodies

I'm adding bullet physics to my engine. The physics simulation bits are all working nicely, but one bit I'm struggling with is being able to move objects using their co-ordinates, and then have them ...
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1k views

### Integrating Bullet3 into a C++ project - Linking to libraries

I've been following the BulletQuickstart guide and I get as far as generating the vs2010 solution and converting to newer. I've also been following this very good answer from a few years ago and have ...
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### bullet raycast vehicle - understanding coordinate system

Bullet world space coordinate system is the same as opengl world coordinate system. I have noticed that raycast vehicle has the following function: ...
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1 vote
274 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: ...
194 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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### 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 ...
59 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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1 vote
496 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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### 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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441 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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### 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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37 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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1 vote
282 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 ...
85 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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746 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 ...
1 vote
8k 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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289 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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2k 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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944 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. ...
527 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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345 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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1k 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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1 vote
1k 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 ...
1 vote