# Tagged Questions

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### 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 ...
114 views

### How to run physics simulation in the background for possible future outcomes?

I'm designing a physics-heavy game in 3d. The core mechanic of this game is that the user gets to choose his actions based on probable future outcomes. For example - the player has a choice whether ...
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### Farseer - Difference between Position, GetLocalVector, and GetWorldVector

I have used Box2D extensively, and am used to just calling body.GetPosition(). But Farseer does not have this. Instead it has a property Position, as well as methods GetLocalVector and GetWorldVector. ...
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### Lunar lander: How to calc acceleration in each step

I'm trying to make a lunar lander simulator. I'm going to use a simple Euler integration. AFAIK all I've to calculate is the acceleration in each step, and then I should be able to update velocity and ...
365 views

### Make fast thing look slow (Box2D)

I'm working on a game that you control a trebuchet to throw balls to the opponent. It's like a game called 'Medieval Siege'. When the trebuchet is swinging its arm, player need to seize the best ...
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### How should I invoke a physics engine?

I'm new to writing games. I'm planning to write a 2D battle game which may require an physics engine. Suppose I've written one, but how can I combine it with the main routine of my game? Should I ...
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### Are collision detection always O(n^2)?

Are physics engine able to decrease that complexity, for example by grouping objects who are near each other and check for collisions inside this group instead of against all objects ? (for example, ...
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### How do I fix objects “popping” or jittering in physics engine?

I've got a simple physics engine that solves collisions by simply correcting the position of overlapping bodies (just circles for now) directly, as opposed to just changing the velocity or applying an ...
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### Is there any physics engine for XNA? [closed]

I am an XNA game developer. I am now starting to develop physics games on XNA but the problem is that I don't know about any physics engine desinged for XNA. Please if you know about it kindly help ...
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### Realistic 2D Planetary Physics Engine?

I'm doing a spaceflight simulator in C++ (using Allegro 5), and I realised that I could just use a physics engine instead of writing my own physics. So that's what I'm doing. Since this is going to ...
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### Pick and Drop the Ball Testing Without Replicating the Physics Frame

I am making a program that pick, drag, and drop the ball. In real life, once you pick the ball and drop it, whenever the available object is (what you see is what you get) will only be picked and ...
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### Resolving a collision with forces

In my 2D physics engine, I can detect AABB vs AABB collisions, and resolve them by finding the shortest penetration vector and adding it to the AABB's position. Doing this "pushes" the first AABB ...
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### how to make virtual environment consistent in networked applications? [closed]

I have a Virtual Environment(grid of cubes) which has the same state on both users when the application starts. Both users have haptic devices, whose position is depicted by a small sphere in the ...
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### Inverse Dynamics How to [closed]

I have some motion capture data (kinect) that records all body joints (32fps) and I want to take particular positions (for example when a person moves both of his hands up in the sky in celebration ...
258 views

### Friction due to gravity in an impulse based physics engine

In my physics engine, I'm using impulses to solve collisions. I'm basing all calculations on these equations: impulse = desired_velocity_change * mass impulse = force * time friction_force <= ...
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### RK4 integration and Continuous Collision Detection

I'm using this method to detect collision between two AABBs. The algorithm is simple, fast and works great. It uses the relative velocity between the two objects to calculate TOI. This works fine with ...
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### How do engines avoid “Phase Lock” (multiple objects in same location) in a Physics Engine?

Let me explain Phase Lock first: When two objects of non zero mass occupy the same space but have zero energy (no velocity). Do they bump forever with zero velocity resolution vectors or do they ...
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### Sharing data between graphics and physics engine in the game?

I'm writing the game engine that consists of few modules. Two of them are the graphics engine and the physics engine. I wonder if it's a good solution to share data between them? Two ways (sharing ...
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### What different ways are there to model restitution in a physics engine?

In my physics engine I give a body a value for restitution between 0 and 1. When two bodies collide there seems to be different views on how the restitution of the collision should be calculated. To ...
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### Stopping an object after applying an impulse or force?

I'm having a small issue where after applying an impulse or force it is impossible to actually get an object to stop, i.e. a velocity of zero. This code is run every 1 / 60 of a second: void ...
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### Calculation of Inertia Tensors

Bit of a complex and lengthy question that, I'll admit, I don't quite understand very well yet so I will try and explain as best as I can. Short Version: Is there a general c++/physx formula out ...
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### Physics engine that can handle multiple attractors?

I'm putting together a game that will be played mostly with three dimensional gravity. By that I mean multiple planets/stars/moons behaving realistically, and path plotting and path prediction in the ...
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### what is the absolute simplest way to add physics to a simple 3D game

This physics does not have to be very complex at all. There are a number of rectangles and one ball, all of which have the appropriate bounding volumes constrained to them, it would be great if the ...
2k views

### Non axis aligned bounding box collision and physics

Exactly how much more expensive, and while we're at it, difficult, is it to have non-axis aligned bounding boxes in your framework? I realise that it very much depends on what you're trying to do, so ...
333 views

### physics model simulation

I am building a game for which I want to simulate certain rigid body dynamics.Could someone suggest me some engines which work on Ubuntu.Also as I have dont have much time to implement it,so it would ...
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### Joint constraints in PhysX

I'm trying to use PhysX for my physics engine. I'd like to use spherical joints, but I'm having trouble with the constraints. All of the examples that I've found refer to SDK v2.8. I'd like to ...
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### How to make a 2D Soft-body physics engine?

The definition of rigid body in Box2d is A chunk of matter that is so strong that the distance between any two bits of matter on the chunk is completely constant. And this is exactly what ...
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### Problem with impulses in my physics engine

I'm currently developing a small 3D impulse-based physic engine for a CS project. It uses GJK for collision detection and is kind of stable at the moment. Nevertheless, I'm not satisfied with my ...
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### Converting 2D Physics to 3D

I'm new to game physics and I am trying to adapt a simple 2D ball simulation for a 3D simulation with the Java3D library. I have this problem: Two things: 1) I noted down the values generated by the ...
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### Havok physics with a wide range of object scales

So typically Havok works best with normal human sized objects with a gravity of 9.8m/s^2 and dealing with everything in meters. In my Game though there will be a large variety of scales from ...
1k views

### Any fixed-point portable open-source 3D physics engines?

I'm looking for a fixed-point 3D physics engine (basic kynematics and collision detection-resolution... nothing too fancy.) I need fixed-point math because I'd like to have deterministic results, for ...
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### gpgpu vs. physX for physics simulation

First theoretical question. What is better (faster)? Develop your own gpgpu techniques for physics simulation (cloth, fluids, colisions...) or to use PhysX? (If i say develop i mean implement existing ...
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### What's the best open source physics engine to use with JOGL? [closed]

I have a past with jbullet but the existing jogl compatible sources and demos seems uncompleted. I have managed to implement it to an extent but still looking for a better documented engine with more ...
1k views

### Optimizing Bullet and ODE Physics on consoles and mobile phones

I'd like to use either Bullet or ODE on low powered devices (mobile and consoles), but the frame rates are below the acceptable 25-30fps for simulations. I've found that one articulated body by ...