# Tagged Questions

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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### Calculation technique for 2D inertia tensors?

Just wondering what the techniques are out there. It's only 2D so I figured there'd be a good chance for there to be a "one size fits all" solution out there that's essentially an analytical solution. ...
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### How do I add collisions to my 3D game made in LWJGL / OpenGL [Java]? [on hold]

I spent 4 hours trying to figure out how I can add collisions to my game and simply could not find ANYTHING. I have absolutely no clue what to start with. What is the simplest way of adding super ...
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### simple but powerful 2D physics engine c++ [closed]

The two big 2D physics engines out there are Box2D and Chipmunk, which can create a lot of complicated collisions. but the only collisions I need to do are grid-aligned AABB collisions, so I just ...
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### Do I need to learn any physics if I use a physics engine? [closed]

Complete novice out here. Of course I know basic physics like mass and inertia. I don't want to make an engine I just want to make a game and use a physics engine made by someone else. Do I need to ...
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### p2.js physics engine behavior on Heightfield

I am writing a small game consisting of a 'ragdoll' character riding a skateboard. I have created a 'skateboard park' with some ramps and a jump. I am using a 'heightfield' object as the ground. ...
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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 ...
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### 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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### Where are the parameters to APEX destructible asset / actor documented?

The NxDestructibleAsset has parameters such as defaultBehaviorGroup.damageToRadius destructibleParameters.fractureImpulseScale p3BodyDescTemplate.density structureSettings.useStressSolver ...
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### simple collision detection with box2dweb

im beginner in box2dweb that version of box2d for javascript i wrote simple gravity system and i want to detect the collision between the box and the ground , when the falling box hit the ground ...
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### Storing rigid body collision shapes in local or world coordinates

I'm writing the beginnings of a lightweight 2d rigid body engine (in javascript, as a hobby project), and i'm debating whether to store collision shapes in local or in (updated as needed) world ...
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### 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 ...
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### C++ FPS game collision detection with partitioning system or physics engine? [closed]

I'm working on a small FPS game (as a hobby and for learning purposes, nothing else) built with C++ in OpenGL (from scratch). Documenting online on the kind of strategy someone would approach with ...
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### Replicating no. of sprites without letting the app to slow down and crash

Is it possible that if I'm making a a simple drag-n-drop game, does making a new sprite via constructor with texture as a parameter makes the game slower and depletes more memory until it crashes or ...
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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 ...
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### Check every body's position and delete or not (box2d performance specific)

I have a simple game with a platform (a ground that's not infinitely long). During the game I have about 10-30 balls on average that'll fall off the platform. There's gravity so I think they'll keep ...
283 views

### Cross Game Engine Compatibility - Multiple Game Engines for one Game

I am new to Game Development, infact getting started with it, so reading as much as I can. I came across game engines. Now atleast I have an idea of what a game engine is, and what it does. In order ...
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### 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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### Mobs living in the physics engine

So, yeah. Mobs (including, and indeed especially, the player), physics engine running (cannon.js), first-person perspective, fairly low-poly-count world because I'm targeting WebGL. I'm trying to ...
284 views

### 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 ...
1k 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, ...
1k views

### animating roulette ball

I'm trying to achieve something like netent's roulette (which is a great product in my opinion). It's going to be implemented in html5. I wonder which path should I take to have such a great ...
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### How to deal with pushing objects out of collision in a physics engine

I'm developing a 3D physics engine (I know, I should use one of the many good existing physics libraries, however my collision detection is optimised for objects with highly ordered highly complex ...
293 views

### 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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### 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 ...
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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 ...
152 views

### Moving Sprite With Physics Frame

Normally, a physics frame in pink (see image below) gives the body for detecting hit signal. It usually either falls down or lifts up depending on the gravity orientation. The question is: Is it ...
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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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### limiting jump forces to achieve a maximum jump height [duplicate]

A player and the world are modeled using a physics engine. Jumping is modeled by applying a vertical upward force to the player's physics body when the jump button is pressed. The upward force is ...
2k views

### 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 ...
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### 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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### What physics engine support force fields and bodies represented as points?

I need a game engine that supports force fields in 2d or 3d, but suitable for 2d calculations, like bullet. Each body I want to simulate is represented as a set of points. Each point has positive ...
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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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### Need Guidance Making HTML5 Canvas Game Engine

So I have some free time this winter break and want to build a simple 2d HTML5 canvas game engine. Mostly a physics engine that will dictate the way objects move and interact(collisions, etc). I made ...
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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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### How to make a stack stable? Need help for an explicit resting contact scheme (2-dimensional)

Previously, I struggle with the sequential impulse-based method I developed. Thanks to jedediah referring me to this paper, I managed to rebuild the codes and implement the simultaneous impulse based ...
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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 ...
2k views

### How to achieve highly accurate car physics such as Liveforspeed?

Liveforspeed is a racing simulator, there is amazing amount of realistic physics. for example, tires get warm, tire actually deforms when you turn corners. You need to play this game with a mouse at ...
581 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: double t = 0.0; const double dt = 0.01; double ...
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### What's the difference between a Game Engine and a Physics Engine?

What's the difference between a Game Engine and a Physics Engine? How do they work together, and what's the meeting point between them?
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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 ...
1k views

### AndEngine Physics: Shape rotating but not updating physics effects

I was looking at PhysicsExample from AndEngine's Examples. I made the following change that I added a vertical line shape and created a fixture for it. Then I registered a rotation modifier for that ...
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### 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 ...
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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 ...