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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Box 2D Set Origin

I'm trying to set the origin of a box2d shape. By default, a shape rotates around the center. But I'm trying to get it to rotate around the left of the shape. Like a clock for example. I've heard of ...
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378 views

How to implement a tractor beam?

I'm working on a game where the player can pick up objects using something like a tractor beam, and carry them around. Attracting the object towards the center of the beam is not difficult. But once ...
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296 views

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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858 views

Bringing a Box2D, Physics Enabled game Online?

Lets say, to simplify the problem of online games a bit, my goal would be to run a near identical simulation on multiple computers in sync. Would sending commands be a good idea? Now if only sending ...
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1answer
246 views

How can I predict player-to-projectile collisions in Box2D?

I'm making a real time shooting game with Box2D as the physics engine. The gameplay is mostly about trajectory, like Angry Birds. I want to make a slow motion effect and move camera to the player when ...
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818 views

multiplayer networking with physics

I'm curious how multiplayer networking with physics is implemented in racing games. We have a physical world with multiple fast-moving vehicles controlled by different people. Let's say that vehicles ...
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3answers
7k views

Determine Resulting Angle of Wall Collision

So I have an object moving in a direction towards a fixed horizontal or vertical wall. How do I compute the angle that the object should bounce off at? The object can approach the wall at an arbitrary ...
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Why do objects interpenetrate in this simple collision solver?

The code below is from a Microsoft XNA sample here. This is quite a simple rigid body simulation that ignores many physical effects (such as angular momentum), but it does try to push objects ...
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471 views

How can I change the acceleration of an object to arrive at a particular time?

I'm trying to write some code to change an acceleration factor so a ball will arrive at a destination in a desired time. The problem is I don't know time (t) but I do know I want it to arrive at (t - ...
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824 views

How do I make a moving object stop smoothly at the end of a path?

There are a dozen ways I could word this question, but to keep my thoughts in line, I'm phrasing it in line with my problem at hand. So I'm creating a floating platform that I would like to be able ...
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1answer
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How do I detect ledges?

In my game, I'd like my character to be able to grab and hold onto ledges, and to be able to pull themselves up if there's room to do so. How do I detect if there's a ledge, and if the character has ...
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1answer
673 views

How to do collision detection for fluids in 3D? [closed]

Is there an algorithm or a technique which can detect the collision between 3D fluids? I currently treat my fluids as dynamic meshes. Is it possible to find collisions with these, or will I need a ...
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4answers
805 views

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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2answers
276 views

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 ...
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2answers
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How to calculate the exit speed of ball bouncing off a solid surface

Hey all, I am working on a simple game to include some rigid body dynamics, involving placing (moving & rotating) some springs to bounce a falling ball into a target area. My problem is correctly ...
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2answers
6k views

how to ignore physics collision of some objects in box2d

I know this sounds silly but I would like some objects to follow physics while others not to collide each other. I tried to achieve them by setting their position exclusively. But then it will ...
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1answer
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Character bouncing off ground due to gravity

Implementing gravity in the game, the character keeps bouncing up and down slightly when he hits the ground, upon debugging the character is essentially bouncing on and off the ground. Not quite sure ...
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2answers
95 views

How do I prevent raycast car wheels sliding sideways?

I've been writing a non-realistic car physics engine as a learning exercise, using this article as a reference. I have a car that correctly collides with a terrain and applies the correct suspension ...
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2answers
484 views

Is it possible to have concurrent collision detection where every entity acts at exactly the same time?

There are many algorithms that can be used for collision detection. In many cases we check for an overlap in coordinates of an entity. If we make a triangle a,b and c. We have 2 entities at a and b ...
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Get collision details from Rectangle.Intersects()

I have a Breakout game in which, at some point, I detect the collision between the ball and the paddle with something like this: // Ball class rectangle.Intersects(paddle.Rectangle); Is there any ...
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2answers
838 views

Show path of a body of where it should go after linear impulse is applied

I am making a game with Andengine and Box2D. I have a dynamic body and I apply linear impulse on the body to move it around when the user have touched the screen. Now I want to show the path where ...
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2answers
778 views

Elliptical orbit modeling

I'm playing with orbits in a simple 2-d game where a ship flies around in space and is attracted to massive things. The ship's velocity is stored in a vector and acceleration is applied to it every ...
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1answer
259 views

How do I change the speed of an object without changing path travelled?

I have a ball which is being thrown from one side of a 2D space to the other. The formula I am using for calculating the ball's position at any one point in time is: x = x0 + vx0*t y = y0 + vy0*t - ...
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1answer
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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? ...
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1answer
267 views

How can I derive force vectors from velocity vectors?

I'm making a 2d shooter ala Geometry Wars. I've got my own simple physics at work driving the background grid and all my entities. To move anything in the world I apply a Vector2d force to it. The ...
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1answer
462 views

2D Polygon Triangulation

I am creating a game engine using the JBox2D physics engine. It only allows you to create polygon fixtures up to 8 vertices, To create a body with more than 8 vertices, you need to create multiple ...
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542 views

Collision Detection/Response in Vector-based levels

I have a 2D side scroller whose levels are stored as vectors (that is, a bunch of lines) which looks like this: How would I detect that I'm colliding with one of these lines, and react accordingly ...
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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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3answers
408 views

Calculating impulse propagation through a rigid body after a collision

I'm working on a game. I need to work out what the impulse is at different points on a body as a result of a collision. For example, in the following diagram, if there is a collision that results in ...
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2answers
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How to implement friction in a physics engine based on “Advanced Character Physics”

I have implemented a physics engine based on the concepts in the classic text Advanced Character Physics by Thomas Jakobsen. Friction is only discussed very briefly in the article and Jakobsen himself ...
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1answer
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Predicting physics/trajectory for pool/billiards games

I'm thinking of making a quick proof of concept of a billiard-style game mechanic, where the player has perfect information of what is about to happen. Here's a good example: I'm only mildly ...
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3answers
5k views

Implementing Separating Axis Theorem (SAT) and Minimum Translation Vector (MTV)

I was following codezealot's tutorial on SAT and MTV and trying to implement it myself but I've come a cropper when it comes to getting the correct MTV. Here is my example: (Cue pretty pictures...) ...
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Is there a good existing starting point for realistic 2d racing car physics?

I'm trying to get a realistic behaving racing car into my 2d top-down game. Making a very simple car that drives around is straight forward but I want a reasonably sophisticated model that models ...
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1answer
759 views

Pseudo-magnet implementation with chipmunk

How should I go about implementing "natural" magnet on a certain body in chipmunk space? Context is of simple bodies lying in the space (think chessboard). When one of the figures is activated as a ...
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2answers
158 views

Pathfinding with inertia

I'm currently working for pathfinding for a game where units are moving, but they have inertia. Most typical pathfinding algorithms (A*, Djikastra, etc.) are simply designed to minimize the length of ...
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3answers
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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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1answer
364 views

Changing orientation by applying torques

Suppose you've got an object floating freely in space. You have a vector you want this object to point towards, and a vector representing the direction it's currently facing. From these two, you can ...
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1answer
510 views

How do I make a slot car game?

I new to game development with Unity and my first project is a slot car racer. For a realistic slot car-like-driving experience, I first build a track with a channel in the track and a pin on the car. ...
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3answers
827 views

Need physics algorithm for modeling ceiling collapse in voxel-based game

I'm looking for algorithms on how to model the physics of cave-ins/collapses for a game idea I am working on. The game allows the player to extensively mine 3D voxel-based asteroids, and I want areas ...
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2answers
907 views

“Super meatboy”-ish replay

I'm making a platformer built from mini-levels - and I want to create a sort of a replay of all the player tries that the player did for the level. My question is - what is the best way to record the ...
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2answers
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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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1answer
360 views

Looking for very simple implicit integration example

I am trying to design a robust cloth system. I have no problem at all simulating things like that using forward integration such as euler, midpoint, runge-kutta, verlet, etc. However, I just can't ...
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2answers
209 views

Timestep schemes for physics simulations

The operations used for stepping a physics simulation are most commonly: Integrate velocity and position Collision detection and resolution Contact resolution (in advanced cases) A while ago I ...
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1answer
428 views

Weird problem with advect program in fluid simulator

I implemented 2d fluid simulator. Solver runs entirely on GPU. All works fine... on my work PC. But on home PC I have some awful glitches, and I can`t understand how to fix them. Empirically I ...
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Are game programmers aware of all the physics derivatives?

I am trying to study XNA for game programming. XNA has many methods that can simplify developer's life, such as reflecting the vector when it hits a solid plane. I know these are good and developers ...
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3answers
1k views

Is it a good plan to use 2D physics for a 3D racing game? [closed]

I am working on a 3D racing game using SDL and OpenGL. I thought it would be easier to use a 2D physics engine, since I really don't need the 3rd dimension. There will be no flying cars or jumps, they ...
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3answers
612 views

3D game on a planet

Would it be much more work to create a 3D game on a planet rather than on a flat plane? What engines would support this and what techniques would I use? An example would be a small sphere the player ...
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5answers
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How do I implement deceleration for the player character?

Using delta time with addition and subtraction is easy. player.speed += 100 * dt However, multiplication and division complicate things a bit. For example, let's say I want the player to double his ...
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Implementing a 2D Platformer Game Engine

Any ideas where I can find info about making 2D jump & run games? I need some general ideas, so I wouldn't reinvent wheel (at least where game design is concerned). Another point is that I am ...
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6answers
571 views

Increasing efficiency of N-Body gravity simulation

I'm making a space exploration type game, it will have many planets and other objects that will all have realistic gravity. I currently have a system in place that works, but if the number of planets ...