# 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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### How do large physics based games (space engineers) deal with coordinates

I have recently been looking into physics engines and low level computing. At some point id like to make my own engine down the road. Something I can't seem to find an aswer for is how physics based ...
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### Ball not bouncing infinitely with perfect elastic collision settings

I'm trying to create a ball that exhibits perfect elastic collisions, meaning it should bounce infinitely without losing energy. Here's what I've done so far: Set the ball's restitution to 1 Set ...
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### Applying impulses simultaneously at each contact point or sequentially?

I'm coding a 2d physics engine in python, and I'm struggling to understand the right way to implement collision resolution when there are multiple contact points. Consider a very simple collision case ...
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### Discretised Physics in Voxel Space

In most physics-based voxel games (like Teardown), there is usually an object-space voxel grid for each object, but no corresponding world-space grid. This means that a voxelized object can be ...
28 views

### Friction effect occasionally not applied

I'm developing a racket-ball behavior, the expected behavior is similar to a realistic tennis racket and ball, meaning both velocity and ang. velocity should be precisely applied when the ball "...
38 views

### Collision manifold between shapes

I am implementing the narrow phase collision detection of a 2d physics engine. The narrow phase takes a list of shape pairs: [(s1, s2), (s2, s5), ...] And for each ...
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### Circle to Polygon & Circle to Circle Velocity Resolution

I am working a 2d physics engine. Polygon to polygon collision and velocity resolution works without issue, but I am struggling to get working circle to circle and circle to polygon velocity working ...
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### How to choose the normal for collision?

Here two objects collide and I use impulse to calculate the velocity after the collision. But because there are two objects, there are two normals. Calculating impulse only requires one normal. My ...
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### Game Physics Engine : Euler integration : why body under gravity is not covering 9.8 meters/second?

I am working on very basic physics engine and I used euler interation which works like below, ...
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### Physics Engine Collision Response

I'm making a game engine with my integrated physics engine and I've encountered a problem where rigidbodies tend to over react in collisions and move around without and intention to slow down, I have ...
1 vote
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### JBullet - Shoving around objects

Sometimes in video games the players can walk up to certain objects for example boxes and barrels and shove them around. How can I recreate this system? What function do I have to use to apply force ...
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### Is it possible to create an actual working physics-based ball bearing in Roblox engine?

Will it allow for making actual wheels, gears and roller coasters?
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1 vote
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### Swept AABB for 3d collisions

https://www.gamedev.net/tutorials/programming/general-and-gameplay-programming/swept-aabb-collision-detection-and-response-r3084/ So I was following the tutorial above to implement swept aabb for ...
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### Forced based physics engine

Most physics engines appear to use impulse based formulations. Is it possible to use a forced based formulation instead with things like repulsive forces for contact constraints be defined by ...
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### Identifying the wall of impact during BSP traversal

I'm building a 2D BSP based physics game and am having trouble implementing what might seem like an easy feature. I'm using Gamemaker as the basis for this project. Basic Info and Point of Impact ...
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### Should a free roaming camera movement be controlled by the physics engine (for smooth movement)?

I have a hobby engine (for fun and research) with a free roaming camera implementation that works by modifying the PositionComponent and ...
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### Does unity transform world to local considering rotation

I want to implement oriented collision in unity as a test, and for convenience I just wanted to know if local space is also based on rotation. I wanted to check at least two objects against each other ...
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### Why doesn't multi-constraint work in this case?

The situation is as follows: There are two objects and there are 3 constraints between the two objects. $$\dot{C}=(\vec{V}_{rel_a} - \vec{V}_{rel_b}) \cdot normalize(\vec{p_{a}} - \vec{p_{b}})$$ &...
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### How to implement 2D rigid body motion?

I'm already depending on two NPM packages for 2D collision and differential equations: sat rungeKutta I've a basic simulation structure, but don't know where to start with to use these two packages ...
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### How to rotate body in server-side physics without imparting angular velocity?

I'm developing a 2D cloud-based MMO using WebSocket and have struggled a lot to get proper working physics on the server side. I'm using Next.js for the client and currently Node.js for the server. I ...
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1 vote
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### Units in Unity?

I have read that in Unity 1 cube of size 1x1x1 and scale 1x1x1 is representing a cube in real life of 1mx1mx1m. Now, the only setting I find, where I can input anything related to Units is gravity, ...
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### Can Box2D be configured to conserve total energy of the system?

What I want I want a physics engine that can support a few dozen balls and polygon objects interacting with each other in a closed environment. It needs to support objects rotating after collision. It ...
321 views

### How do you resolve continuous collision in a multi body system?

I've been trying to figure this out for weeks but every resource only provides answers for a single body. As far as I can tell for a single body you Find the time of impact Step up to that time ...
71 views

### Dynamic bodies falling onto static body tunnel through each other or fail to bounce

I have a problem with Box2D when 2 dynamic bodies fall onto a static body located below when their restitution is non-zero. They tunnel through each other instead of a rigid elastic bounce. If I treat ...
1 vote
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### How to update the version of Box2D used in AndEngine?

I need help to use an updated Box2D library where the current version is > 2.3.0. I am unable to find a compatible library and do not know how to compile one for use with the Java Native Interface (...
297 views

### How to stop player when they hit an axis aligned bounding box?

I'm in the process of creating a game using electron and HTML5. It's going to be a pretty basic story-based platformer, but I'm ...
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### Why is my Moon not orbiting Earth in my physics demo

I am in the midst of making a gravitational body demo for my physics engine. For the demo, I am trying to simulate both all the inner planets' (Mercury-Venus-Earth-Mars) orbits around the sun, as ...
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### Is it advantageous if the conflict resolution for a 3d game is fake?

The game is you are a monster trainer in "3D" (I am going with WildPet(WP) for the game and the monsters). In battle with one other WP, you give the WildPets commands which can be tactical ...
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### Why do physic engines apply force fully linear, despite adding torque

I checked how the applyForce function on rigid bodies in 3 different physic engines work (cannon.js, matter.js, PhysicsJS) and it seems that this is the common way ...
4k views

### Moving player inside of moving spaceship?

INTRO: I am trying to achieve a spaceship that flies through space and the pilot can get out of their seat and walk around the ship and place physics objects in it while the ship is moving, rotating, ...
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1 vote
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### Configurable Joint rotation doesn't seem to respect mass difference

The Problem I've run into a physics issue in my Unity project, and have put together a simple example scene to illustrate it. Hopefully someone will be able to tell me if I'm doing something wrong. In ...
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1 vote
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### What can I set in rigid body and collidable objects to ensure that the angle after collision is larger?

I have a rigid body with sphere shape attached and a static collidable box. When sphere hits the box at an angle, for some reason, the angle that it bounces off from is really small: https://imgpile....
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### In physics engines, what are the differences between moving an object with transform.translate and using RigidBody related functions like AddTorque?

I'm trying to recreate the ball maze puzzle game from Breath of the Wild with Unity. This is what I currently managed to make: As you can see, it's not nearly as smooth and I feel like I lack the ...
867 views

### Unrealistic billiard ball movement

So, I have this problem, even when I apply a small amount of force, the balls seem to get pushed away easily. Here's how they should behave (GIF from 8 ball pool game): And here's how I have it : ...
297 views

### character movment and physics on 2d game

I'm developing a client/server multiplayer game. in server side i need prevent players cross map objects like walls also i need prevent player go inside each others, instead want to slide them along ...
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### Simulating a small world with Box2D

I would like to use Box2D to simulate a small world, with entity sizes around 1cm (0.01m), some smaller than that. Box2D's FAQ says twice: Your moving objects should be between 0.1 - 10 meters. You ...
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1 vote
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### Should delta be applied to every change per frame ? (e.g. acceleration, deceleration, jump, etc.?)

I have written a game based on another game's original physics. I have all the constants the original game used in the Sega Megadrive. For example: ...
580 views

### How could I move an object, while respecting the gravity and other related physics in Unity?

How could I move an object, while respecting the gravity and other related physics in Unity? I tried using the following approach: ...
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### In games physics engines, what is "tunneling", also known as the "bullet through paper problem"?

I have recently had an issue where sometimes a collision would not be detected. Someone told me that maybe I had an tunneling issue. In the context of game development using physics, what is tunneling?...
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1 vote
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### How to avoid CollisionShape2D bouncing which prevents Area2D detection?

Consider the player with a rectangular CollisionShape2D: and a round enemy with a CollisionShape2D and a little bigger ...
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### Difference between _process(delta) and _physics_process(delta)?

The documentation is pointing one main difference, this is the concept of being synced or not with the physics engine, so the delta parameter has more chance to be ...
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### What is causing my wheel collider's raycast to fail?

I'm making custom car suspension(Custom wheelcollider etc), now I encountered a problem where if car gets dropped from a certain height, raycast will fail to detect collision and wheels intersect with ...
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### Calculating the bouncing ball bounce height while on platforms

I tried to calculate the bounce height for the bouncing ball however it ends up shaking against the moving platform after it finishes bouncing. grav_val in this ...
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### Predict future position of a moving body in Phaser arcade physics

I am looking for an equation for predicting the future position of a moving arcade physics body in Phaser 3. The body has drag applied and isDamping set to true. Phaser applies the drag using the ...
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### Simulation step size in a physics engine

I am trying to integrate a physics engine (Bullet) into my game engine, but I immediately found that I do not know how big should I make the simulation step. I think of 2 options: Use a fixed step ...
I've been developing simple 3D impulse-based physics engine. I calculate impulse as follows: j_r = \frac{-1(1+e)v_r\cdot\hat n} {m_1^{-1}+\bbox[yellow,5px,border:2px solid red]{m_2^{-1}}+(I_1^{-1}(...