# Tagged Questions

Relating to the motion of objects through space (in 2 dimensions (x,y)) and time. Including concepts such as acceleration (thrust and gravity), mass, collision response, friction and more.

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### Car movement in arcade racing game

I am finishing a very basic 2D racing game with top-down perspective. I can't get the appropriate formulas to make the movement of the cars fun and addictive... Do you have tips on how to achieve that ...
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### Good way to implement really basic physics in Flash?

I'm making a somewhat simple side-scroller in Flash. The way I'm currently doing the really basic physics(you don't fall through floors/can't walk through walls) is that I have a big symbol of all the ...
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### How can I simulate a magnet that attracts a ball in a 2D enviroment?

I am making a top-down game where you have to move a ball from point A to point B. You are attracting the ball using magnets that are standing still. The ball needs to get pulled by multiple magnets. ...
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### How do I implement friction in a billiards game?

I'm having trouble implementing friction in a billiards game. Currently, the ball only slows on collision with the edges, but I also want some friction with the background. How can I implement ...
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### Game physics / 2D Collision detection AS3

I know there are some methods you can use like hittestPoint and so on, but I want to see where my movieclip colliedes with another another movieclip. Any other methods I can use? by any chance does ...
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### Physics in carrom like game using cocos2d + Box2D

I am working on carrom like game using cocos2d + Box2D. I set world gravity(0,0), want gravity in z-axis. I set following values for coin and striker body: Coin body (circle with radius - ...
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### How do I move a 2D top-down racing camera smoothly and show what's ahead of the player?

I'm trying to make a camera that follows a race car. Right now, I'm smoothing the camera movement out by moving the camera's position a fixed percentage lerp'ed from the camera's position to the car's ...
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### Shapes and sprites in SVGs

I understand SGV images are used in 2D games to store shape data for the physics engine of the game. I'm unsure though, should the raster sprite also be stored in the SVG or should it be separate? ...
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### Why doesn't this 2d physics calculation yield the desired jump height?

I found a formula for gravity and jumping in this article: http://error454.com/2013/10/23/platformer-physics-101-and-the-3-fundamental-equations-of-platformers/ I implemented this formula and ...
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### Implementing character movement using real physics

This is the first time I'm seriously developing a game so apologies if I'm missing the obvious. In my 2D platformer I adopted Box2D since it seemed like a natural solution to model gravitational ...
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### Using Box2D / Physics with Tiles?

Here is my issue. I currently have Box2D setup and working. But, it works with my Entity system. So I can create static objects and dynamic moving ones, and they simulate fine. However, my world is ...
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### Using forces to reach a specific velocity

In my game, I currently move the player by directly setting its velocity on key press events. This makes the game feel very responsive and allows the user to quickly change direction. However, I ...
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### Physics movement prediction is way off [closed]

I'm making a simple, non-networked game. There are two players and a ball. In implementing the AI for the second player, I've run into a huge problem predicting where the ball will hit the ground. ...
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### Writing an autopilot for a 2d game with newtonian physics

The subject says it all. I am making a 2d space game with newtonian physics and I need pointers on how to write an autopilot for it. The requirements are best explained by an example. There is a ...
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### One-way platform collision

I hate asking questions that are specific to my own code like this, but I've run into a pesky roadblock and could use some help getting around it. I'm coding floating platforms into my game that will ...
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### Collision Detection for a 2D RPG

First of all, I have done some research on this topic before asking, and I'm asking this question as a mean to get some opinions on this topic, so I don't make a decision only on my own, but taking ...
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### How do I change my gravity and jumping logic to put the character at a specific height at a specific point in time?

I'm making a 2D platformer on Android using libGDX. One thing I've had a problem with recently is gravity and jumping. I found a few tutorials on the internet and was able to come up with this... ...
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### How can I make a car follow the terrain in a 2D (side-view) game?

I'd like to create a game where a car drives over a 2D terrain. Which algorithm to use so the car will follow the mountain incline?
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### How to resolve concurrent ramp collisions in 2d platformer?

A bit about the physics engine: Bodies are all rectangles. Bodies are sorted at the beginning of every update loop based on the body-in-motion's horizontal and vertical velocity (to avoid sticky ...
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### Find meeting point of 2 objects in 2D, knowing (constant) speed and slope

I have a gun which fires a projectile that has to hit an enemy. The problem is that the gun has to be automatic, i.e. - choose the angle in which it has to shoot, so that the projectile hits the enemy ...
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### Using box2d DrawDebugData with multi layer scene?

In my Game, a Scene is composed by several layers. Each layer has different camera transformations. This way I can have a layer at z=3 (GUI), z=2 (Monsters), z=1 (scrolling background), and this 3 ...
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### 2D Boat controlling physics

I'm working on a top-down 2D boat game with Unity3D. I couldn't able to understand how to implement physics of rudder controlling. My physics knowledge is not enough to think how rudder dynamics work. ...
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### My pool balls often jump around when there are two or more balls colliding/touching

I'm working through the book 'Introduction to Game Physics with Box2D' and I've created a little pool game with the example code. Despite the name, there is NO box 2D used in this particular exercise. ...
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### Unity WheelJoint2D will not rotate when increasing motor speed

I have a wheel joint 2D attached to a game object in Unity: In its associated wheel script I am increasing the motor speed as described in the tutorial. public class Wheel : MonoBehaviour { ...
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### Frame-rate independent friction on movement in 2d game

I have been trying to implement a simple physics system for a 2D space game I am making. I have it pretty much working, but I have encountered an issue with the way I apply friction. I have tried ...
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### Inverse Explosion with Unity2d

I am currently trying to make all other objects push away from the player when the player explodes. It currently works, but it pushes close objects a little and far objects very far. What I want is ...
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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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### android game-logic for shooter

Im creating a 2d game for android. I'll just get right to it. I have a sprite controlled by a joystick that needs to shoot, sofar Ive managed to get direction and movement on my bullet, but then I ...
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### Canvas Rotation collision detection on a sprite

I am using this code to detect collisions between two rectangular sprites. intersect: function(other) { return this.x < other.x + other.width && other.x < this.x + this.width ...
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### 2d Collision detecton axis aligned boxes

I have recently run into some trouble with my collision detection. My game is composed of a map made out of axis aligned squares. The player has an x and y velocity, and I want to know how I can find ...
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### How can I manage the deceleration of units so that they arrive on-target?

When I first started trying to set up my air units' movement in my RTS game, I thought it was going to be easy with simple Euler method linear acceleration. This was far from the case as the ship ...
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### Formula for Planetary Alignment

I am attempting to create a game where there is a universe of two 16-bit addresses ranging from -32768, -32768 to 32767,32767, or in hexadecimal, each value can run from \$8000 to \$FFFF then 0 to ...
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### Implementing a motorized hinge joint

I have a 2d physics engine, with three boxes: "body", "left wing" and "right wing". The wing boxes are connected to the body using a hinge joint. The physics world has no gravity. I'm attempting to ...
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### Best practice for organizing the physics of objects?

Apologies because this is a long post and I am inexperienced. I would really appreciate the input from some experienced developers. These are my two goals for this project: To learn the best ...
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### 2D physics rotation w/ XNA

I'm creating a simple game with space ships made of blocks that are all the same size. After having looked at this: Calculating the rotational force of a 2D sprite I have created the following code ...
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### How do I convert a partially transparent image into polygons?

I'm using GLEE2D, a level editor allowing me to import images, scale them, rotate them, and position them onto layers and export the data into XML format. However, it does not tell me objects' ...
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### Understanding Torque in Unity

This is (hopefully) a simple question that should avoid me asking a more complex question. This is in Unity (2D) but hopefully this is a general physics principle I am not getting. I am applying a ...
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### How to calculate new velocities between resting objects (AABB) after accelerations?

lately I have been trying to create a 2D platformer engine in C++ with Direct2D. The problem I am currently having is getting objects that are resting against each other to interact correctly after ...
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### What's the best way to handle slopes for a platfomer game using Box2D

I would like to know if there is any known solution for handling the player's movement on slopes using Box2D engine. I tried to do it using a circle as the player. Everything was fine until I tried ...
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### How do I set up moving platforms in a 2D side scroller to interact with the player properly?

Edit: I changed the way that gravity was applied so that it is applied even when a player is standing on a block, so instead of the game outputting that you are stepping on a tile as true and false ...
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### Physics in a 2D oblique perspective game

So, just to clarify, because I'm still fuzzy on the terms for perspectives in older games myself, examples of an oblique perspective can be seen in many older RPGs (Earthbound, Final Fantasy, Secret ...
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### Need help with collision detection/resolution in a 2D simulation of 'worm-like' creatures

(originally posted this on regular stack overflow, somebody pointed this forum out :-) ) Hi there, I'm implementing a physics engine for the simulation of worm-like creatures. Problem is, is that ...
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### Converting 2D Physics to 3D

I'm new to game physics and I am trying to adapt a simple 2D ball simulation for a 3D simulation with the Java3D library. I have this problem: Two things: 1) I noted down the values generated by the ...
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### Sprite Kit - containsPoint for SKPhysicsBody?

I have a ball bouncing around the screen. I can pick it up and drag it onto a "bucket". When my touches finish, I use the containsPoint function to check and see if I have dropped the ball onto the ...
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### How to impale and stack targets correctly according to the collider and its coordinate?

I'm making another simple game, a catch game, where a spawning target game object must be captured using a skewer to impale it. Here how: At the start, the falling object (in red) will fall in a ...
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### How should I model rotation caused by bounce friction? [duplicate]

In my Java2D simulation, I have a disc which, when it bounces off the boundary of a 2D region, begins to rotate, as if it had gotten some spin from the wall. I'm having trouble relating the ...
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### AndEngine - Moving Rectangle using Accelerometer

I'm learning how to create games with this great engine and I'm trying to put my knowledge in order to create a simple game. My first goal is to make a Rectangle moving using accelerometer and create ...
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### How to implement Ragdoll physics to 2D characters in XNA?

I'm starting a new project with XNA. I want to create a game where the main character is subject to ragdoll physics when killed. I was wondering if anyone can give me any tips on how should I ...