Questions tagged [physics-engine]

Software for simulating physics like collisions, forces, mass, joints, motion etc. Examples of physics engines are PhysX, Havok, Bullet and ODE.

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58
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5answers
8k views

What exactly is a physics engine?

A program should take input, process it and give output. So what exactly does a physics engine take as input and provide as output?
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6answers
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How can I perform a deterministic physics simulation?

I'm creating a physics game involving rigid bodies in which players move pieces and parts to solve a puzzle/map. A hugely important aspect of the game is that when players start a simulation, it runs ...
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6answers
19k views

How do I build a 2D physics engine? [closed]

The most advanced games I've made are a 8-ball pool game made with the physics engine Box2dFlashAS3 and a platform game with levels. When I did platform games, I've always wished to know how to make ...
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7answers
27k views

What are some known 2D/3D physics engines for XNA? [closed]

I'm looking for a physics engine to use in an XNA project (2D or 3D). Because it's for XNA, it needs to fulfill some requirements: Not necessarily free, but close to it is obviously preferred Managed ...
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4answers
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Do any open source JavaScript 3D physics engines exist? [closed]

I'm working on a web-based 3D FPS game using WebGL, HTML5 and JavaScript. It is supposed to target PCs and net-books with WebGL-enabled browsers installed. I'm wondering if there's an existing open ...
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3answers
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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 ...
14
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5answers
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Why integrate over accumulation?

I'm starting to learn how to DIY physics, and I have a question about implementing integration at the most basic level (i.e. this is not a Euler vs. RK4 question). Nearly every example I come across ...
14
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3answers
7k views

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, ...
14
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1answer
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Any fixed-point portable open-source 3D physics engines? [closed]

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 ...
13
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4answers
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How should I handle tiny objects in a physics engine?

I am making a 3D physics engine for throwing dice. Up until now a dice has been 1x1x1m and gravity has been 9.82 m/s^2. This of course does not look realistic as the dice will respond to everything in ...
12
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1answer
20k views

How do I integrate bullet physics into my game?

I downloaded the release file found here, but I'm just not sure where to start. In my game I have a number of oblongs and a sphere, I want all of these to collide with one another. (They all have ...
12
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3answers
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Advice needed for a physics engine

I've recently started a project, building a physics engine. I was hoping you could give me some advice related to some documentation and/or best technologies for this. First of all, I've seen that ...
11
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3answers
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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 ...
10
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4answers
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How to build a bones animation engine?

I want to develop a flash game. It would draw a stick man, and edit his pose. I think what I need to learn are bones animation and physics engine. Can anyone introduce some good resources to learn ...
10
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3answers
5k views

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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2answers
5k views

Making a character move along a curved slope in a World with gravity

I have seen this game Fancy Pants 2 . And the thing I noticed apart from the physics and beautiful animations is that the character is moving along slopes , even curved slopes. I have little ...
9
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3answers
1k 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 ...
9
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2answers
2k views

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 ...
8
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1answer
1k views

Finding the point of collision

I'm writing a 2D rigid body simulator. The objects being simulated are convex polygons. My question involves how to decide on the "point" of collision, so that when I apply a response force, I can ...
8
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2answers
404 views

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 ...
7
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1answer
2k views

Calculating impulse with multiple collision points

In my amateur 2D rigid body physics engine for a game I react on collisions between two bodies with an impulse j (formula 11) as explained here. To calculate this impulse I need one contact point P ...
6
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4answers
378 views

physics engine without time steps

I'm looking for physics engines that doesn't use time steps. I don't think time steps are reliable, and I don't like how without tweaking the engine a bullet going too fast can pass through a wall ...
6
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4answers
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Is it possible to use the GPU on a mobile device to accelerate a particle physics engine?

I am interested in answers for any mobile device but I am mainly considering the iPhone and devices that run Java. I am developing a game that relies heavily on a particle physics engine for core ...
6
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3answers
6k views

Applying angular velocity to quaternion

I am reading Game Physics Engine Development by Ian Millington currently. In his book, he represent an orientation of rigid body by quaternion. I don't understand the formula where he apply angular ...
5
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2answers
457 views

What are the technologies that makes physics engines so good for raycasting?

again. This question is strictly related to this one so, what is the technology that makes physics engines suitable for raycasting? It is a particular data structure? Has it to do with the engine's ...
5
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1answer
954 views

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 ...
5
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2answers
784 views

multiple contacts for SAT collision detection

I have implemented SAT algorithm for obb-obb intersection and I am able to generate a contact for this collision type. My problem is that SAT only generate ONE contact and in many situation I need ...
5
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1answer
7k 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 ...
5
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2answers
3k views

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 i ...
5
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1answer
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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 ...
5
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1answer
1k views

Realistic Trajectory of a Projectile [closed]

When simulating an airplane and a missile, to get them moving in the air we apply a force in one direction. Now an airplane has wings that keeps it afloat while a missile can have fins to stabilize it....
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3answers
10k views

How can I make my main character move in a parabolic arc when jumping?

I'm entering Android game development, and I already have a computer version of a game I want to publish. The thing is, I want to make this as good as it can be. With that said, I need a physics ...
4
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3answers
4k views

Why do we use physics engines for collision testing or raycasting?

There is a thing I don't understand about game engines: why it is so common to use physics engines to do raycasting or collision testing? Say that you have a 3D scene loaded in your scene manager (...
4
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3answers
516 views

Sound Synthesis from object collision in Virtual Reality Environment

I have a project whose subject is "Sound Synthesis from object collision in Virtual Reality Environment" First of all, I have to define some objects with certain attributes (like shape, mass, material)...
4
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3answers
1k views

Semi Fixed-timestep ported to javascript

In Gaffer's "Fix Your Timestep!" article, the author explains how to free your physics' loop from the paint one. Here is the final code, written in C: ...
4
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1answer
775 views

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 ...
4
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2answers
2k views

What are the disadvantages of R-Trees in collision detection?

I was poking around in SQLite and discovered R-trees. A little digging revealed that R-trees are really just fancy AABB-trees. Then I realize that the state of the art in collision detection (often ...
4
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0answers
387 views

3D Physics Engine Collision Response: Solving Simultaneous Collisions via equation

I have been implementing a basic physics engine for a small game project I'm working on. It has very specific requirements, so I decided to try and write my own physics engine to meet them. I found ...
4
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1answer
1k views

2D Spaceship Thruster Movement - Turning

I have a spacecraft (shown in the image) built out of ‘blocks’ / 3D planes. It is drawn within a 3D space, but I’m ignoring the Y axis for now and keeping things on a “2D” XZ axis. The ship has a ...
3
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3answers
468 views

Why does a physics engine produce different results each run through?

There are no random numbers in the engine and everything is calculated the same way. How can it happen differently each time? This is on my own small physics engine that I made earlier that is ...
3
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2answers
686 views

What other components would one have to combine with Ogre 3D render engine to make a full fledged custom game engine?

I have heard that Ogre 3D is not actually a game engine, rather it is a 3D render engine. I have also heard people claim that one can piece it together with other components (engines?) to create a ...
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3answers
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 ...
3
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2answers
1k views

How do I calculate rotational impulses in rigid body collisions?

I'm writing a simple 2D physics engine to help me understand the inner workings of physics engines. I'm following Randy Gaul's tutorial which can be found here and It's been extremely useful and ...
3
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2answers
2k views

What is a “solver” in a physics engine?

I am self-taught and have successfully coded simple collisions of planes, spheres, rays and up until interactive cloth simulations so I do have some basic sense of which part of the physics goes where ...
3
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3answers
297 views

Physics System ignores collision in some rare cases

I've been developing a simple physics engine for my game. since the game physics is very simple I've decided to increase accuracy a little bit. Instead of formal integration methods like fourier or ...
3
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2answers
1k views

What is inertia in a physics engine?

Inertia seems to be useful in a physics engine, so useful that even in Box2DLite, a demo of Box2D it hasn't been omitted. See this Body class from Box2DLite: ...
3
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1answer
661 views

Data oriented design in physics engine

I am new to data oriented design and I am currently developing a physics engine as a hobby project. I am really interested in data orinted design but I am not sure how to apply data oriented design to ...
3
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2answers
559 views

Bounding volume hierarchy - linked nodes (linear model)

The scenario A chain of points: (Pi)i=0,N where Pi is linked to its direct neighbours (Pi-1 and Pi+1). The goal: perform efficient collision detection between any two, non-adjacent links: (PiPi+1) vs....
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1answer
1k views

Design patterns in Game Physics

In the frames of a number crunching compatible programming language (say.. C++), what would be an elegant solution for adding self collision, external collision and integration step (Euler, etc.) ...
3
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1answer
1k views

Cutting a body in box2d

After cocos2d, I'm looking at box2d... And I have some questions: I was wondering how to cut a body into pieces. How do I determine the intersection point of the body with the cut line? Create a new ...