# 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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### Calculating initial velocities given trajectory parabola

I'm working on a volleyball game but my maths/physics knowledge isn't quite up to par. I need some help with the following problem: The player can hit the ball from anywhere on the left of the court ...
37 views

### How to find or compute or look for overall/max RPM by simply checking for rotation?

I find it hard to determine the wheel RPM since I'm only making a simple 2D game of rotating object via Z-axis. I wanna try this solution but I got no change since I'm trying to find the RPM from a ...
250 views

### OnTriggerEnter() without rigidbody?

I know this is an old question and it has been answered for a lot of people. Unfortunately none of the solutions apply to the problem I seem to have with rigidbodies. I have a moving AI character and ...
102 views

### Unity Player Smooth Left - Right Movement

I am learning Unity 3d . Now I want to move the player object (The Ball) , Left and right by Left Arrow and Right Arrow key . I want smooth movement when the player goes left , but I don't know how to ...
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### How do I make a box don't slide up/walk normally on a slope?

I'm trying to implement slopes in my game. When I walk up the slope and suddenly stop, here is what happens: And when I move down, it goes like this: I have set density to 0.5, friction to 0 on ...
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### Bullet Physics / OpenGL Meshes Not Colliding

This is for a school project, and I'm having a bit of trouble with Bullet acting strangely. I have an OpenGL project with Bullet Physics library working with Assimp model loaders and Magick++ ...
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### How does a car earn nitrous in racing game?

Take the case of Need for Speed, why would a car earn nitrous gas by drifting or by flying in the air? What's the rule of collecting nitrous in other racing game? Is there a general formula within ...
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### Bullet Physics: Applying a force at the point of collision

Suppose I want to simulate some kind of gripper with two "fingers" (such as pair of pliers, or two-fingered robot hand), picking up an object from the ground. Both the gripper and the object are ...
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### Should I compute impact damage with energy or momentum?

My game uses physics (Box2D in particular). Just about every object in the game can be destroyed, and the primary method of combat is by slamming objects into one another at high speed. It makes ...
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### Character Movement in 3D games

I'm either not searching correctly or there is really not a lot of material on Character Movement in 3D games. I'm mostly interested in how people usually implement character movement in games like ...
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### 3D Planetary gravity

so i am making a thing in javascript and i want to have planetary gravity in my "universe". But when i use an equation to calculate the acceleration by gravity i get one number. That is how fast the ...
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### Can this script be edited to create a “shotgun” type spread when firing? [Top down shooter]

I have this code and I'd like to add a shotgun to the game by slightly modifying the code. I've looked online for any example but everything I find is for FPS not a TDS. void Shoot () { timer = ...
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### How to Create levels in game in libgdx [closed]

I am create trying to create a Android game using Libgdx. I want to Create levels in game . So what i do. Which classes i need to use and how to create them explained. Plz help.Also i want to add ...
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### Configurable Joint, linear limit range

I am working on a physics driven pressable button, but I cannot seem to tackle the minimum and maximum limits. This is the rig I have set up for the button (as it looks when pressed down). 2D view: ...
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### Bullet Physics Collision is Not Detected

I have created two btConvexTriangleMeshShape objects. One is a cube of size (0.1 x 0.1 x 0.1), and the other is is a plane of size (1.0, 0.1, 1.0). The plane is static, and the cube is dynamic, and ...
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### Interpolating positions between FixedUpdate frames in Unity?

Lockstep Framework uses FixedUpdate () in Unity to match an assumed fixed timestep. At higher rates, FixedUpdate doesn't at all run at a fixed rate but instead runs multiple times in a single frame to ...
118 views

### How to predict future position of an object(bullet sync)?

There is a multiplayer game and server sends to all clients a message when a shot happens, containing bullet position, bullet velocity and timestamp. By having timestamp, we can calculate the lag, let'...
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### Test if Jump can reach target

I have an object that can jump. When it jumps, its Y velocity becomes -600 (pixels/second). For up to .2 seconds, it can ignore gravity. After .2 seconds, it begins to accelerate downward at 2100 (...
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### Why do Physics Engines use collision margins?

When using a physics engine in a game (such as Bullet), you usually need to define a collision margin for each object. I'm a beginner to game development, and I don't understand the purpose of a ...
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### Computing a full revolution for an arbitrary orbit?

I'm making a game in which the goal is to get as many planets as possible to orbit around a star. The user launches planets at any distance away from the sun (as long as it's on-screen), and in any ...
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### How can I change my angular momentum correctly using Unity3d physics?

This is an odd question to ask here, but I've almost been pulling my hair out trying to solve this. Plus its more of a mathematical/physics problem than a programming one. I'm trying to implement ...
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### Newton physics “hiding” rigid bodies

It seems like creating a bunch of rigid bodies (say 100K) causes a huge slowdown. However, what if the model the rigid body is attached to isn't visible. Is there a way to remove the rigid body from ...
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### Box falls extremely slow? (~1 pixel per second)

As the title says I have a problem where my box2d bodies falls extremely slow. Around 1 pixel per second. My world is stepped like this world.Step(1 / 60.0f, 8, 3);, each frame. The way I update ...
164 views

### Collisions between sprites in SpriteKit

I'm making a game in XCode using SpriteKit. The game has a player and different types of projectiles that he has to avoid. When the player collides with the projectiles, the score changes and the ...
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### Unity Physics Trouble with Platform Objects

Hi Game Development Community! I'm new to designing in unity, and I'm having some issues with my player game object traveling through platform game objects. Several of my game objects (pink in ...
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### Calculate Jump Limits

My question is in a similar vein to this question, I am creating a pre-mapped pathfinding solution much akin to how Ash Blue was for my 2D platformer-style game (in XNA). As part of the process, I ...
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### Calculating Linear force required to hit a specific vertex on a parabola

The idea is a user presses somewhere on the screen and the program will fire an object in a parabola shape from a defined start position that has it's vertex where the user touched the screen. I have ...
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### How to adjust my games speed to fps [duplicate]

Hi so i am making a small sort of physics engine, but if your fps is really slow the physics will update slower and objects will move slower. How do i make the speed of objects greater if the fps is ...
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### Orbits: Combine the Pros of RK4, Symplectic Euler, and Verlet Velocity Integrator

Recently, I've implemented and compared a number of basic integrators for my physics engine. The 3 that gave me the best results are RK4, Symplectic Euler, and Verlet Velocity, but I think I need ...
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### Is this a correct backward Euler implementation?

I want to simulate a mechanic object like this: init acceleration a; init velocity v; init position x; loop { get delta time dt; v = v + a*dt; x = x + v*dt; } I use the velocity (which is the ...
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### Leapfrog integration vs Euler integrator

I am looking at various integration methods for my n-body simulation and I'm slightly confused about actual implementation of leapfrog integration. According to the wikipedia page leapfrog method is ...
128 views

### How can I create a set of collision points for an arbitrary mesh?

In my project I am working on automatically deforming an arbitrary mesh with respect to another arbitrary mesh, within the context of user generated content, similar to this deformer being developed ...
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### What is vector<E> how to use in android java [duplicate]

I making game i want use vector into velocity,position and rotation. But i don't know how to wark vector so please help. Thank you
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### Why do my Box2D bodies not fall, even though world.step is called?

I have SFML set up with a Box2D world that has gravity, but my bodies won't move. I std::cout'ed the position of the body in the game loop, but it's always at (0, 14)! No errors or warnings, just no ...
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### 2D Physics: storing previous position vs storing velocity

I saw a number of 2d game tutorials and books where previous position of an object was stored in state instead of velocity vector. Velocity is then calculated each frame as a difference between ...
231 views

### What are the basic equations in 2D physics collisions?

I'm making a 2D fighter, and I have gotten a basic engine, but right now I need to add the collisions, but I'm sure a basic AABB check will not be enough. I'm sure it needs some basic 2D physics ...
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### Colliders for moving inside a spaceship when the whole spaceship is made of a single mesh (in Unity)

I've begun to study a unity engine in one purpose: I have a great multi player game idea! The main essence: In space there are two (or even more) huge spaceships with crew consisted of players (all ...
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### Change in direction should slow down object and accelerate in new heading (2D grid-based)

I'm trying to implement some sort of faux space physics in my 2D game. I have a top down view of my space ship. You can change direction and set a speed up to a maximum which then accelerates the ship ...
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### Trying to get Box2D bodies to fall [SFML, Box2D, C++] [duplicate]

As the title says I'm trying to make my Box2D body to fall, but it won't work. It just stays at the same position. Sorry for the long codes but I have no idea where I'm doing something wrong, so I ...
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### Unity 2D Hingejoints break under extreme force

I have added a rope to my game that is made up of multiple small gameobjects, each connected to eachother by a HingeJoint2D. Since 1 unit of mass in Unity is supposed to represent 1 kg, I've made the ...
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### Orbital mechanics: orbit as a function of time. Universal variable formulation?

I am trying to model a two dimensional orbit for a two body Kepler problem but have gotten stuck when introducing the time variable. For a satellite with known semi major axis (a), eccentricity (e), ...
33k views

### How to make a character jump?

I am currently making a game in C# using Direct X 9.0. The game remake is Donkey Kong NES. I have nearly everything completed, but I am having problems with the physics of Mario's jump. I have ...
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### How to prevent accelerating along wall during 2d sliding collision response

I'm writing a simple 2d physics system using a circle colliding with edges. When the user presses a key the circle's velocity is incremented by some amount in the direction they pressed. There is ...
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### Using Box2D for soccer physics

I've learned quite a bit of Box2D and I've succeeded basic stuff concluding ball physics. I want to implement 'opposing forces', as the character kicks the ball with a certain strength, with the leg ...
523 views

### What is wrong with my 2D orbit calculation?

I am working on a 2D game, and I am working on adding some space physics, so I need to find a way to create a circular orbit. I want to make my game object move on a circular way around a planet. I'm ...
3k views

### Kepler orbit : get position on the orbit over time

I'm developing a space-simulation related game, and I am having some trouble implementing the movement of binary stars, like this: The two stars orbit their centroid, and their trajectories are ...
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### Finding the components of Proportional Navigation in 2D

So, I've been scouring this, the Physics Exchange, Wikipedia, and the general web for information about Proportional Navigation, and I can't seem to wrap my head around how to find the individual ...
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### 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 ...
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### What does maximum normalized frictional force mean in this tutorial?

I tried following this tutorial: https://nccastaff.bournemouth.ac.uk/jmacey/MastersProjects/MSc12/Srisuchat/Thesis.pdf, but in page 19 I ran onto a problem - I don't understand the step 4. It is also ...
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### Do physics engines take shape into account or they operate solely on predefined variables?

I have never given it much of a thought about how physics engines operate behind the scenes. Though, I am currently working on a game that would greatly benefit from as precise as possible physics ...