# Tagged Questions

Relating to the motion of objects through space and time. Including concepts such as acceleration (thrust and gravity), mass, collision response, friction and more.

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### How to detect and collide two elastic line segments?

There are 4 moving physical nodes in 3D space. They are paired with two elastic line segments / strings (1 <-> 2; 3 <-> 4). Part I: How to detect the collision of two segments? Part II: On the ...
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### 2D game - Missile shooting problem on Android

I have to make a tank that sits still but moves his turret and shoots missiles. As this is my first Android application ever and I haven't done any game development either, I've come across a few ...
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### How does 2D Game Physics work? [duplicate]

Possible Duplicate: How do I build a 2D physics engine? If we take the game Angry Birds that had big success lately I were thinking how do they implement the physics in a game like that? Your ...
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### 2D Ragdoll - should it collide with itself?

I'm working on a ragdoll fighting game as a hobby project, but I have one dilemma. I am not sure if my ragdoll should collide with itself or not, i.e. if ragdoll's body parts should collide. 2D ...
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### Determining relative velocities on impact?

I'm trying to figure out a way to determine the relative velocity of a body colliding with another in a 2D environment. For example if one body is moving at (1,0) and another traveling behind it ...
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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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### Powder games: how do they work?

I recently found these two gems: http://powdertoy.co.uk/ http://dan-ball.jp/en/javagame/dust/ My question is: How are the physics with so many elements efficiently handled? Am I just severely ...
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### Physics in my game confused after restructuring the Game loop

I'm on my way with making a game in Java. Now I have some trouble with an interpolation based game loop in my calculations. Before I used that system the calculation of a falling object was like this:...
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### Collision Detection for 2D

I am working on a simple game, where I need to do a collision detection of two Texture2D. The code I have written is: bool perPixelCollission = false; Texture2D texture1 = sprite1.Texture;...
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### Follow point of interest by applying torque

Given a body with an orientation angle and a point of interest or targetAngle, is there an elegant solution for keeping the body oriented towards the point of interest by applying torque or impulses? ...
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### Development platform for 2D web and mobile games

Is there a game development platform -- similar to Torque, or Unity -- which can be used to deploy 2D games on the following platforms: Web iOs Android Xbox Live Arcade (Preferred but not required) ...
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### Soft body, where to start learning?

I want to ask you about some resources to learn simulating soft bodies, do you know some good knowledge sources? I asking because I want to make car crash simulator, I've made something but it didn't ...
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### What causes Box2D revolute joints to separate?

I have created a rag doll using dynamic bodies (rectangles) and simple revolute joints (with lower and upper angles). When my rag doll hits the ground (which is a static body) the bodies seem to ...
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### car crash android game

I'd like to make a simple 2d car crashing game, where the player would drive his car into moving traffic and try to cause as much damage as possible in each level (some Burnout games had a mode like ...
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### Who know how to implement the 2D bone animation showed in the game?

I wonder how do they implement the bone animation in the flash game http://www.foddy.net/athletics.swf Do you know any study materials which I can start to learn 2D bone system from? I just ...
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### 2D platformers: why make the physics dependent on the framerate?

"Super Meat Boy" is a difficult platformer that recently came out for PC, requiring exceptional control and pixel-perfect jumping. The physics code in the game is dependent on the framerate, which is ...
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### Calculating the force of an impact?

I'm trying to figure out a way to determine the force two objects collide in. I have two vectors defining their linear velocity at the time of impact, their mass and their angular velocity. Keep in ...
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### Farseer - Apply Impulse

I'm new to Farseer and have a simple question. The demos I went through didn't seem to demonstrate what I want. I would like to apply an impulse (not force) to an object at a specific position on that ...
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### Lag compensation with networked 2D games

I want to make a 2D game that is basically a physics driven sandbox / activity game. There is something I really do not understand though. From research, it seems like updates from the server should ...
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### Analysis of Mario game Physics [closed]

I know there's a breakdown of Sonic the Hedgehog physics found here, and I was wondering, does there exist a breakdown of any of the Mario games? Something similar to this but for Mario is what I'm ...
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### Ragdoll on alive creatures: has somebody already implemented it?

I find that a dead creature falling realistically is boring. I wonder, has any game implemented an animation system where the model moves depending of the muscle forces and the velocity of the limbs, ...
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### Forcing one projectile to follow close behind an initial projectile

I'm shooting out a projectile and I want another projectile to closely follow it. I can't simply shoot out the second projectile at a slightly lesser time because the first projectile may change ...
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### Water/Ocean simulation and physics

I'm looking for some references about water simulation, and how to model it's interaction with bodies (like boats, ships, submarines). I've found a lot of references on the visual aspects of water (...
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### Resources to learn programming rigid body simulation

Where I can start learning about simulating rigid bodys 2d and 3d ?
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### Quad tree vs Grid based collision detection

I'm making a 4 player co-op r-type game, and I'm about to implement the collision detection code. I've read a lot of articles and stuff about how to handle collision detection, but I'm having a hard ...
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### Farseer and 2D Action sidescroller game

I'm thinking about using Farseer inside my game (I'm not good in physics), which isn't a bad idea. However something happened while I was thinking about that, I found this tutorial: http://www....
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### Self-righting agents that have fallen over

I need insect-like agents that have fallen/rolled on their back/side to naturally re-orient themselves. The agents are modeled as simple cuboids in the physics engine (Bullet) to approximate an ant-...
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### I'm trying to learn the “digital physics” required to do a floating network of spheres

If that is even what it is called. What I am trying to do it: http://asterisq.com/products/constellation/roamer/demo Can someone please point me to towards a book or in vaguely the right direction? ...
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### Is it worth it to use Bullet for 2D physics instead of Box2D for the sake of learning Bullet?

There isn't much more to the question. I'm not concerned about overhead, as I'm sure they are both fine for my purposes. Basically, I am familiar with Box2D concepts because of the Farseer Physics ...
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### When should I use a physics engine?

Since I found out Box2D, I'm using it for kind of any game-like application I try to write, from very small prototypes or small programs to test something, to actual projects. Thanks to it it's so ...
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### How are physical model programmed in simulation games?

Being a Gran Turismo fan, I'm wondering what are the algorithms used to compute realistic behavior for friction, aerodynamism, velocity, curves etc. Also, are there sophisticated ways to simulate ...
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### How to implement 2d explosions that will cause damage taking into account covers and distance?

How can I implement a 2D explosion in a way that it will cause less damage to characters that hide behind crates or other cover? Ideally damage will depend on the strength of the cover (e.g. metal ...
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### How do I model a gooey sprite?

I happened to see this structure of a gooey player character made in flash. Can anybody suggest onto what computer science concept I should use to make a goo make it behave like a goo Thanking ...
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### What do I need to change in Box2D to work in pixels?

Box2D seems to be set up in such a way that you cannot work in pixels (i.e. physics scale = 1). It produces very strange results as it hits maximum speed limits at low speeds and looks very strange. ...
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### Arc'd jumping method?

Okay, so I'm making a platformer, and I wanna know how I can make a arc'd jump easily. Like what Mario does in super Mario Bros 1. Any ideas on a simple way to accomplish this?
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### Strangeness when simulating a chain

I'm using box2d and I simply hook up 10 points each with a similar length constraint to the adjacent point. When I move 1 point, the others follow just like a rope/chain. Just like one would expect. ...
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### How would one generate a texture for cracks in different materials?

I would want to have the ability to simulate different variables like brittleness, or other variables to get varied end results. I would mainly need to generate impact cracks, so it would need to ...
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### How can I implement rectangle collision response?

I am working on a game in JavaScript and my current implementation of collision uses the shortest distance to push the intersecting object away, which isn't always correct. I've made this diagram of ...
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### How to create complex Physics scenes with the Havok Content Tools

For example, Havok Content Tools allows you to define physic bodies, properties, connections, etc in Maya, 3d Studio Max, etc. For creating full scenes/levels is this really the correct approach or ...
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### Fundamental physics component(s) in component-based game engine

What are the "smallest" physics components in your component-based game engine? Would it make sense to create something like Positionable, Rotatable, Movable, Collidable and combine them the way you ...
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### 3D Particle-Geometry collision

I am programming a particle engine for a 3D game written in XNA. I was wondering if somebody could point me in the right direction or perhaps give me some pointers in making the particles collide with ...
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### Determing an object's position along a curve over time

I have some objects in my game which are "thrown". At the moment I am trying to implement this by having these objects follow a parabolic curve. I know the start point, the end point, the vertex and ...
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### How do I implement deceleration?

I say "deceleration" because I'm not using acceleration at the moment; what I mean is moving the velocity back towards zero, eventually stopping. I'm new to vectors and not so great with physics and ...
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### 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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### Car (or other “object”) acceleration and braking: how to?

I'm not good in math so I'm here to ask you how to manage, in a simple 2d game, the car acceleration and braking. I'm trying to develop it (as a hobby) in c# and sdl.net.
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### Realistic slow-falling snow algorithm?

Is there a good algorithm that simulates falling snow? I'm particularly interested in snow that falls slowly, so it doesn't quite fall in a straight line but deviates a bit. Maybe even including ...
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### Taking Physics into account for AI Planning

What I've seen in most Game Engines and game engine design is that the Physics Engine is the be all end all system. Basically, AI for example may want to travel to some position, but it simply ...
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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 ...