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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Time complexity of solving constraints in physics engine

Erin Catto mentioned in a talk that solving constraints precisely requires cubic time and quadratic space. What algorithm is he talking about when he mentions cubic time? pdf of slides with following ...
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Elastic collisions between cubes and walls

I have a simple scene with two cubes and walls as shown bellow. The right ball starts moving with initial instant force along the x-axis and collides with the first ball and reflect off a vertical ...
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1answer
59 views

What is wrong with my gravity calculation?

Im trying to create a method to calculate the fall time for an object using real formulas. Well I came up with this: ...
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0answers
23 views

Real-time 3D Scene-reconstruction into Physics Engine

I am trying to create a game where the user scans the room using RGBD camera and reconstructs 3D scene. This scene would be integrated into physics engine, after an object recognition algorithm tells ...
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1answer
684 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: ...
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1answer
183 views

Physics engine and rigidbody sleep optimization

I am trying to add sleep optimization to my little physics engine(just for learning). I use SAT for collision detection that returns penetration normal and depth without contact points. Objects are ...
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1answer
24 views

Having trouble with btGeometryUtil::isPointInsidePlanes

I'm in the process of parsing a BSP file to create btConvexHullShape objects for each brush. I've seen a few examples of how to do this on Github and they all use the getVerticesFromPlaneEquations ...
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1answer
214 views

Calculating real time moment of inertia around arbitrary axis in 3d

I have a 3d rigid body consisting of multiple triangles forming a closed mesh. I know how to calculate the moment of inertia around an arbitrary axis by splitting up the mesh into simpler shapes and ...
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2answers
545 views

How to get the point of collision in Separating Axis Theorem?

I'm interested in the relatively precise point (not line) of collision for calculating angular velocity on impact for use in a impulse calculation. At first I thought, perhaps naively, that I could ...
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1answer
328 views

Rigid body falls through static mesh even though collision is detected

I'm using Jitter Physics to create a game. For testing, I have ball (a spherical rigid body) falling onto a small box-like mesh. The problem is that the ball falls straight through the floor, even ...
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1answer
504 views

How would joints work in an impulse-based physics engine?

I want to learn about physics engines, especially impulse-based ones. So I've followed along this tutorial to create some simple rigid-body physics: http://gamedevelopment.tutsplus.com/tutorials/how-...
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2answers
105 views

AABB Collision Detection Confusion

I am trying to understand and implement AABB collision to learn simple 2D game physics. I'm following a tutorial and its method is a bit different to other websites. It uses the center of the object ...
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0answers
54 views

how can I visually compensate for latency in a diep.io style game

implementing extrapolation using linear velocity, orientation and position like on here gafferongames.com/post/state_synchronization/ I'm a little confused if I want to extrapolate from a known ...
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2answers
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Can I use the 2d physics engine in a 3d game (or viceversa) in Unity?

This is entirely for performance. The 2D physics are less expensive, but I require 3D for some scenes. I never need both at the same time. I know you can have 2D with an orthographic perspective in a ...
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42 views

Simulating circular motion with gravitational forces in Unity2D

I am currently messing around with a game where you control a black hole and use its gravity to fling planets at targets. I have the gravity calculations working pretty well when the planets start out ...
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0answers
34 views

RigidBody Collision Handling with Verlet Integration

Hi I'm reading the Jakobsen Paper "Advanced Character Physics" which explains how the verlet integration along with a tetrahedron (4 particles) can form a structure usable for rigidbody (with 6 length ...
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40 views

Calculating approximations of support/forces between objects in Unity

I'm looking for ways to calculate how much a given object supports another in a scene. For example, imagine a box is on a table. In this situation we may say the table provides support to the lamp (...
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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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0answers
26 views

Numerical errors in Player collision offset causing player to fall through the ground the next frame, how to avoid?

I'm trying to implement player physics with arbitrary objects, in this case, a bunch of cubes. I wanted to add a "floor" so in my cube collision function, I added the following following lines: <...
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42 views

Implement MMO like character movement without a full-fledged physic enginge?

Question: How can I implement World of Warcraft / Guild Wars 2 / etc like player movement, including jumping, without using a full-fledged physic system for my multiplayer game since players only ...
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2answers
52 views

Objects aren't rotating in sync

This is a follow-up question to How to reapply force applied to one object to another object I want to make two objects move, react to collisions and other stuff as if they were one. For example, ...
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0answers
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How do I prevent falling tiles from bouncing on each other in my match 3 game?

I am working on a match 3 game in Unity. The tiles have a RigidBody2D in dynamic mode and a BoxCollider2D. When a match occurs ...
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2answers
44 views

How to reapply force applied to one object to another object

Edit: While I wasn't able to make the code work completely, I believe my question has been sufficiently answered. I want to make two objects move, react to collisions and other stuff as if they were ...
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0answers
72 views

Faster convergence in a physics engine

I've got my hands on the first edition of the book Game Physics Engine Development: How to Build a Robust Commercial-Grade Physics Engine for your Game by Ian Millington. Because I didn't really know ...
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2answers
132 views

How to handle player input with fixed rate variable fps time step?

I've made a system which uses the ideas from "Fix your Time Step" in order update physics. I'm having trouble finding standard methods for dealing with this when user input affects player movement ...
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1answer
258 views

Terrain collision with sphere and OBB

I'm implementing my physics engine for my 3D game. So far I've been able to implement collision detection between OBB, spheres and planes. The engine generate contacts and resolve them with an ...
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0answers
27 views

Polygon doesn't bounce enough in edge-ground collisions (but it does in vertex-ground collisions)

I'm currently making a (basic) physics engine in Python in which I want a polygon to bounce off the ground (\$y=0\$). When a vertex hits the ground, I apply the (linear) impulse $$\overrightarrow{P}...
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2answers
77 views

Problem making wave animation

I want to simple wave-like animation using mesh. I thought that it would look like a wave if there would be a point at the middle of the mesh and change z axis of that point, and after this I change ...
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0answers
62 views

Is it better to combine or leave alone 2D polygons

I'm making a modular system for a 2D spaceship arcade like game, the user builds their own ship with equilateral triangles to make more complex shapes. When the ships are small it's no problem, but as ...
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0answers
19 views

how to find point intersection of two segment in 3d after they collide? [duplicate]

I'm working on collision boxes project and I found a problem that when I detect the collision with the algorithm of SAT and knew that the collision was edge\edge I couldn't find the the point of ...
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1answer
42 views

Detect collision point [duplicate]

I'm writing a 3D rigid body physics engine, I am using OpenGl for simulation. Only convex objects are considered. My question involves how to detect the point of ...
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0answers
103 views

Bullet physics convex hull center of mass

I am trying to make a convex hull collider for bullet physics. I am using BulletSharp.CompoundShape and BulletSharp.ConvexHullShape. This is model of a chair in unity with rigidbody and convex mesh ...
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1answer
114 views

Minimal, unrealistic physics engine

I'd like to prototype a game with custom, very simple physics. Something similar to older games, anything from Super Mario to Quake 3 Arena. I'd prefer to avoid realistic physics engine because they ...
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0answers
58 views

Solve Constraints with linear factor of 0 in Bullet Physics

In my code I need to set the linear factor for velocity to 0 (sometimes). For example, game->rigidBody->setLinearFactor(btVector3(0, 0, 0)); When this is done,...
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1answer
232 views

Impulse resolution for purely rotational collisions (relative linear velocity = 0)

I've been writing a basic physics engine, (loosely) following Randy Gaul's online tutorial. I have been using this equation that he derives: $$j=\frac{-(1+e)((V^A-V^B)*t)}{\frac{1}{{mass}^A}+\frac{1}{...
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2answers
31 views

Dividing properties between RigidBody and Collider

I am currently making a physics engine in Rust. The 2 main data structures concerning collision detection are: RigidBody: Physics-related aspects of the body. Contains a reference to a Collider ...
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2answers
510 views

Understanding constant acceleration in terms of game physics simulation

There are various integration methods that can be used for games. I am trying to write a simple physics engine deciding between semi-implicit Euler and Verlet variants. What I don't understand is ...
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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 ...
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0answers
38 views

Full energy transfer between two identical objects

I'm trying to simulate a game like billiards / shuffleboard / curling where two objects collide and under a perfect direct hit all energy is transferred to the second object. Both ...
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1answer
200 views

Box2D physics are different on server and client

I'm using C# Box2D library for my server and client, they have similar world.step(), iterations and update function. At the same time they have different physics' results, difference is not fixed, it ...
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4answers
3k views

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 ...
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1answer
140 views

How do force fields scale?

Setting I am designing a 2d game in which a \$1/r^2\$ force acts between moving charged particles, and the number \$n\$ of particles is very large. To calculate the force between all pairs of ...
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2answers
657 views

Physics engine and squishing of stacked objects

I have a general question that seems to apply to most physics Engines (Box2D, Unity, Matter.js, …). I'm trying to make a tower of rectangular objects that are stacked on the [static/mass=infinity] ...
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1answer
1k views

Physic engine for snooker/billard game [duplicate]

Possible Duplicate: Is there an algorithm for a pool game? I think most billard/snooker games have a lot of problems with their physic engines. They are far away from realistic and you can't ...
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0answers
114 views

Unity like RigidBody physics in PyGame

I am trying to make game but first I want to make simple simulator. The goal is to have a ball fall onto a surface and then roll off the edge. Here is my code: ...
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1answer
9k 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 ...
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2answers
959 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: ...
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1answer
455 views

Unity Physics Simulation - Limitations / Inaccuracies? Bounciness of a ball (pool/snooker balls etc)

I am playing with Unity physics engine. I have a pool table and a cue ball. Both have Physic Materials. If I start the game, with the ball floating about 1m above the table, it falls and bounces (...
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1answer
52 views

How to make a motorcycle running on a vertical circular track(loop-da-loop) without falling down due to gravity?

I am currently developing a game, motorcycle type game. Of course, my map is not just made up of simple line or curve. For example: a vertical circular track in the map. i've seen most 2D motorcycle ...
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1answer
197 views

Wall collision response results in jittery physics

I have the following game loop : ...