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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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Whats the most efficient way to implement precise ray picking for scenes with large meshes?

I'm wondering how to implement ray picking in the most efficient way for scenes with very large meshes ( > 1 million faces)? Right now I'm using BulletSharp physics wrapper with TriangleMesh which ...
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1answer
54 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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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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1answer
44 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 ...
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33 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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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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26 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 ...
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1answer
79 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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21 views

How to use btCompoundShape with btRaycastVehicle?

I use btBoxShape for creating a chassis btRigidBody. Then I define an initial position for the chassis rigid body, for example btVector3(0, 10, 0) and when ...
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1answer
120 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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24 views

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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33 views

Center of World Map not the same as the center of my Bullet Physics World

As you could see in the image, the center of my map should be located at the intersection of the diagonal lines. When I import 3D buildings within the area into my Bullet physics world, I want to set ...
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14 views

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
59 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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33 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
48 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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1answer
43 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
97 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
80 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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152 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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1answer
94 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
22 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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0answers
167 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
55 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
61 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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1answer
3k 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
171 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
898 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
470 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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1answer
269 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
242 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
676 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
590 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
106 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
474 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
114 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
374 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
260 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
241 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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293 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
99 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
248 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
230 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
556 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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1answer
247 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
1k 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
2k 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
497 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
763 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 ...