Tagged Questions

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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0answers
12 views

Bullet Physics, btRigidBody Problems [on hold]

I am learning game development and I have problems when I was developing my character, I am using btRigidBody to my character. I created a jump, move (using impulses) and duck actions for my ...
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1answer
55 views

How can I get a 4x4 matrix from a bullet quaternion?

I'm trying to make a game using JavaScript with Ammo.js ( an implementation of bullet ) and Sylvester to do my matrix maths. The problem is I don't know how to turn the WXYZ that bullet gives into the ...
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1answer
100 views

In a TPS, how to aim bullets to the direction the camera is pointing, but make the shooting from the player?

(In C#/XNA.) I mean, I can't find an answer nowhere. I'm trying to learn how to make a Third Person Shooter, especially like the one I found in a game called "M.A.R.S.", from Epic Games. I don't want ...
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1answer
63 views

Multiplayer and creeps (NPC enemies): how to compute bullet hits given the lag?

We are making a multiplayer co-op game, where players will shoot not each other but AI enemies (creeps), controlled by the game. The chosen implementation is client-server with an authoritative ...
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1answer
88 views

Friction not working for Vehicle in BulletPhysics

I am creating a vehicle using bullet-physics engine (v 2.82). I created a ground ( btBoxShape ), a box and a vehicle (following the demo). But friction between ground and vehicle wheels seems not ...
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2answers
63 views

Libgdx, find Vector3 direction

I am using Libgdx along with Bullet physics. I have a vehicle moving. I would like to use a ray from the vehicles origin and in the vehicles forward direction. How can I create the forward Vector3 ...
0
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1answer
89 views

Bullet - objects falling through

I have problem with bullet collisions. You can see problem on this video (around 0:18): http://goo.gl/DiVP8l Objects are "embeded" inside vertical bars - that is not correct - they should be ...
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2answers
152 views

What torque should I apply in Bullet to maintain a vertical orientation?

I have a RigidBody in Bullet. Each frame, I want to apply torque to correct its orientation toward an upright position (i.e. near-zero pitch and roll). I know its angular velocity and orientation. ...
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1answer
91 views

Irregular oval collision detection

I am using a physics library based on the Bullet physics engine. How do I create an egg shaped object or a cylinder where the width differs from the depth (i.e. with an oval shape)? I'm not looking ...
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0answers
69 views

JBullet quaternion to Euler angle conversion causes strange flipping behavior

I am making a game using JBullet (a Java port of C++'s Bullet library) for the physics and LWJGL for the graphics. However, JBullet measures angles in quaternions and LWJGL uses Euler or ...
2
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1answer
107 views

How can I use imprecise accelerometer data for controls?

I want to rotate an object with respect to the phone's position. I use the accelerometer output to detect orientation: float roll = Gdx.input.getRoll(); float pitch = Gdx.input.getPitch(); float ...
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1answer
140 views

Bullet 3D Physics Objects Not Rotating?

So I've got Bullet 3D controlling the motion of objects rendered with DirectX. In the clipping below I've got 2 identical rectangles & 5 balls. The lowest rectangle has a mass of 0 and doesn't ...
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2answers
251 views

How to implement a simple bullet trajectory

I searched and searched and although it's a fair simple question, I don't find the proper answer but general ideas (which I already have). I have a top-down game and I want to implement a gun which ...
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0answers
43 views

Bullet Physics ConvexDecomposition?

I've looked at Bullet Physics ConvexComposition Demo and would like to implement that in my game but the code is so undescriptive and it's hard to understand what is going on. Would any of you people ...
0
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1answer
98 views

Using Bullet physics engine to find the moment of object contact before penetration

I would like to use Bullet Physics engine to simulate the objects in 3D world. One of the objects in the world will move using the position from 3D mouse control. I will call it "Mouse Object" and ...
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2answers
179 views

LibGDX - draw bullet physics bounding box

I am very new to game development and I am trying to debug my 3d collision bounds. Could somebody give me an example on how to draw the collision bounds of an object in libGDX? I assume it has ...
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0answers
59 views

Collision at incorrect height between boxes and btHeightfieldTerrainShape

I'm using btHeightfieldTerrainShape from BulletPhysics for collision between fired boxes and a terrain. But such boxes seem to collides at higher positions above the terrain as the following picture. ...
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1answer
37 views

Bullet: Get steepness or slope between positions

In a CharacterController object, there is setMaxSlope(btScalar slopeRadians) The max slope determines the maximum angle that the controller can walk up. But how about knowing it in advance? Like ...
2
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0answers
114 views

Quaternion - rotating rigidBody to particular angle over time

Using Bullet Physics. There's a rigid body that is rotated. For some delta-time I need to rotate that body to have rotation of (0, y, 0) - keep the old y value rotation but reset x and z. The ...
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0answers
64 views

Exporting .bullet file from Blender Render

I'm trying to export my blender render bullet world to a .bullet file. Unfortunately, it seems like when I bring my bullet world to the game engine it drops the bullet info. Is there a way to export ...
2
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1answer
322 views

Conceptual - What is the optimal way to combine steering behaviors with rigid body physics?

I am working on a simple 3D space simulator that makes use of the Bullet physics engine. The spaceships are rigid bodies that have a mass and hitbox so that they can be considered for collisions. At ...
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1answer
84 views

Bullet softbody nodes messed up positions [closed]

I recently switched from Havok physics to Bullet because I wanted to have soft body collisions, but I don't have any budget to license the (superior?) Havok solution, I couldn't even try those ...
2
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1answer
95 views

What are the parameters for btHingeConstraint::setLimit

What does each parameter in btHingeConstraint::setLimit do to the hinge constraint? void btHingeConstraint::setLimit ( btScalar low, btScalar high, btScalar _softness = ...
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1answer
82 views

Bullet3: Issue with applying force once an object is at rest

I just started using bullet and I'm having an issue where once my rigid body is at reset at the floor it won't move when I apply a force to it. I have created a small demo to show this using the ...
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1answer
250 views

How to draw a plane equivalent to a given btStaticPlaneShape using OpenGL

With all other shapes in bullet, you can easily get the transform from the MotionState which holds the origin, the scale, and the rotation. There seems to be no way to get the same information about a ...
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1answer
71 views

x-inverted obj importer in BulletSharp - whats wrong?

See importer C# code at the repository. Screenshot: Left: bullet imported version, right: correct 3ds max version. It's somehow inverted. If you think that left part is just 180 degrees rotated you ...
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0answers
188 views

Bullet Physics Raytrace Picking

I'm having trouble picking using bullet's raytrace code Here's what I have so far for creating the actual Ray float top = 1.f; float bottom = -1.f; float nearPlane = 1.f; float tanFov = (top - ...
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1answer
102 views

making rigid body stop using friction

how am I suppose to apply friction to an object so that when I apply force it decelerates eventually to zero? Here are my physics objects: Rigid Body "Sphere" Collision shape: btSphereShape(0.50) ...
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votes
2answers
210 views

Spherical / Relative Gravity

I'm working on an Ogre3D + Bullet project that involves planets in a solar system. For all intents and purposes, I'm looking to give each planet it's own gravity sphere. So far, all I've found are ...
0
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1answer
379 views

How to use Bullet physics with Entity Component Systems?

I have an Entity Component system and I want to have a Physics Component that would add the given object to the physics simulation. My problem arises because the Bullet API requires me to add each ...
2
votes
1answer
424 views

bullet character controller sliding down any slope gradient

I've been experimenting with the btKinematicCharacterController. I've seen very old complaints that it has issues but I can't find anything recent stating that these issues remain (and nobody ever ...
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0answers
38 views

Bullet simulation stops after windows inactivate

I am having trouble when inactivating window (event resizing); all the contents get rendered and input works. Even the physics work but the btDiscreteDynamicsWorld stepSimulation function does not get ...
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2answers
223 views

Best collision shape for rooms

I'm wondering what is the most efficient collision shape to use with APIs like Bullet or Havok for rooms/interiors. Rooms tend to be boxes but are concave since the normals point inward which means no ...
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1answer
436 views

how to predict enemy postion to shoot bullet same kingdom rush

i'm doing a tower defense game same kingdom rush, enemy can run curve not only linearly. i found this link : 2D tower defense - A bullet to an enemy but this link use only for enemy run linearly. ...
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0answers
299 views

Bullet Physics Simulation Running Slow

I'm in the process of converting my game engine from java which used the LWJGL and JBullet to c++. However, when I was implementing Bullet physics my simple simulation of a box dropping from specified ...
2
votes
1answer
227 views

Bullet physics weird behavior . Jittering and drifting with btBoxShape

I'm working with bullet physics, and I have some weird behavior. What's happening is that as a simple test, I'm dropping a simple box onto a plane from 100 units. It's important to note that the ...
3
votes
1answer
440 views

Create a physics body with hole : bullet physics

I am writing an iOS game, using bullet for physics, blender to create models, cocos3d as the game engine. I have a model like this Basically there is a plane, with a hole, and a UVSphere. Both were ...
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2answers
1k views

How to set the object's world position in bullet?

In my Ogre3d application I am first changing the parent of a node like this: // save object "Cube" into node*; then ... Vector3 absPos(node->_getDerivedPosition()); Quaternion ...
2
votes
1answer
42 views

Stick 2 btRigidBodies together

I have a platform with btBoxShape as shape, and I want to rotate it every certain amount of time to simulate a rotating platform. Right now I rotate it with Ogre (my rendering engine) and use a ...
4
votes
1answer
728 views

Bullet physics debug drawing not working

Background I am following on from this question, which isn't answered yet. Basically I have a cube and a UVSphere in my scene, with UVSphere on the top of the cube without touching the cube. Both ...
3
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1answer
1k views

Create bullet physics rigid body along the vertices of a blender model

I am working on my first 3D game, for iphone, and I am using Blender to create models, Cocos3D game engine and Bullet for physics simulation. I am trying to learn the use of physics engine. What I ...
0
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1answer
527 views

Detect when a bullet rigidbody is on ground

I have a rigidbody that is on top of a plane or another rigidbody. How do I check if said rigidbody is on top of it? I tried to check the Y-part of the velocity but it is never 0, it is always a ...
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2answers
342 views

Jump without bouncing in physics engine

I am using Ogre3D as my rendering API, and OgreBullet as my physics engine. I have an test entity that when the y part of the velocity is 0 and spacebar is pressed, the velocity changes to, lets say: ...
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2answers
450 views

How to correctly create bullet rigid from custom .mesh in Ogre?

Being new to 3d programming and bullet physics in particular, I am wondering how a 3d model or the mesh generated out of it effects the accuracy of bullet physics simulation. I have written a ...
1
vote
1answer
356 views

Need help with a complex 3d scene (using Ogre and bullet)

In my setup there is a box with a hole on one side, and a freely movable "stick" (or bar, tube). This stick can be inserted/moved through the hole into the box. This hole is exactly as wide as the ...
2
votes
0answers
149 views

Bullet btGeneric6DofConstraint and btGeneric6DofSpringConstraint constructor arguments

I have a very simple (and maybe too primitive to post here but I’ll try anyway :P) question about Bullet constraints. What are arguments const btTransform &frameInA, const btTransform ...
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votes
5answers
1k views

How to save and restore Bullet Physics state?

I'm looking for information on how to save the runtime state of rigid bodies with Bullet Physics. Most of my world consists of static objects, but I have a few dynamic and kinematic objects as well. I ...
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2answers
915 views

First person camera with Bullet Physics

Before integrating the Bullet Physics, the camera worked fine. But instead of using my own simple struct for transform data, I use rigid body structs provided by the physics library now. There are ...
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1answer
45 views

How to squash stretch the Bounding box so as to get Good Physics effect

I have Surrounded a game Object with a rectangular Box and applied Physics properties to that Box so that load on the computation gets reduced. But i have a problem, whenever in animation if the Game ...
2
votes
1answer
459 views

Bullet physics: how to make a soft body “static” (kind of)?

I'm fairly new to Bullet and started using it a week ago. I mainly played with rigid bodies and everything works as expected but now that I also need to add soft bodies into my simulation, things got ...