# 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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### Equation to make small number big and big number small (gravity)

I have a sprite that I want to speed up as it gets closer to another object. I really want this to flow well and don't want a series of if statements. All I can think of is to take the distance and ...
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### How to deal with corner collisions in 2D?

I'm writing a top down 2d XNA game. Since its my first I'm trying to write the physics and collision stuff myself to learn it. Whenever my player sprite character attempts to move into a position ...
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### How to make a 2D Soft-body physics engine?

The definition of rigid body in Box2d is A chunk of matter that is so strong that the distance between any two bits of matter on the chunk is completely constant. And this is exactly what ...
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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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### Variable physics step, bad idea?

Currently, when I update the entities I calculate the time passed since the last update, and then pass that to their update function. They will in turn pass that duration to all their components. ...
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### Calculating the angular direction from velocity

I'm trying to calculate the angular direction of a projectile, knowing it's X and Y velocity I can find the magnitude of its movement, but I'm having a hard time wrapping my mind around getting the ...
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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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### Is it possible (from the vertex shader) to always draw at specific pixels?

I am wondering if I can (if possible) make a vertex shader that will always make the pixel shader draw everything in 1 pixel, at position 0,0. I know this sounds crazy, but it's needed in the ...
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### Solving for velocity in the x/y/z axes?

In a 3D environment I have an object with a displacement x that I know I need to traverse in a given time interval. I have the object's heading and elevation and I want to figure out the distance the ...
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### Best Android gaming engine for Billiards game? [closed]

What is the best engine/way to go with when implementing a 2D billiards game? I am thinking about Emini Physics Engine, which is free for use and stuff, but maybe you can give me some pitfalls about ...
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### Creating similar effects of Geometry Wars in 2D only

I want to create a game with similar effects to that of "Geometry Wars"... for those who have never played the game, basically, massive amounts of 'bending' and 'warping' effects are done on the ...
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### 2D game collision response: SAT & minimum displacement along a given axis?

I'm trying to implement a collision system in a 2D game I'm making. The separating axis theorem (as described by metanet's collision tutorial) seems like an efficient and robust way of handling ...
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### Projected trajectory of a vehicle?

In the game I am developing, I have to calculate if my vehicle (1) which in the example is travelling north with a speed V, can reach its target (2). The example depict the problem from atop: There ...
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### How to get the physics just right in a physics driven game

I'm working on a physics driven game using a java port of Bullet (JBullet). In our game we have a ball that can have collisions with the other objects, including the objects that define the ...
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### Random map generation - strategies for scattering/clustering random nodes

I am doing a simple 4X strategy game in space where each node is a point-of-interest (a planet, an asteroid and etc.). To randomly generate a map, I would follow the steps below Decide how many ...
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### OpenGL vs physics?

I am very new to game programming and I am in my first project. I have come to a point that I need expert advice: Now for the game physics to be able to work on objects, it needs to know each object'...
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### 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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### Tiling Physics using Farseer

I'm having a problem with the Farseer Physics Engine, where in a tiled environment, my object will at times interact with corners of others objects, even if they align perfectly. I've read about ...
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### What is a good book on physics for game development? [closed]

I'm looking for a good beginners' book on the subject of physics in game development. Something that focuses on 2D games would be preferable.
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### How to get object to lose less velocity as its speed increases

I'm developing a game in Flash and I need a little help. It can be considered a math problem. My object is flying with speed X and my object can collide with stones. When it collides with a stone, I ...
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### Designing the main classes in a solar system simulation game in C++

If this is not the right place for this question, could you please direct me to a more suitable site/forum? I'm a beginner in game development (and in the use of this site). I've worked with C++ only ...
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### How can I cancel a contact in a b2ContactListener?

To know when contacts happen we can derive from b2ContactListener and implement our own solution which is great. I'm wondering is there anyway we can cancel a contact, that is to say when we hit begin ...
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### Bodies are colliding but refusing to rotate in Box2D

I'm running box2d in C++ and hooking it up to C# via p/invoke. All physics stuff occurs in C++. My problem is that bodes know when they are colliding and do so with great precision. However if I have ...
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### 2D Platformer Collision/Physics Problems

I'm making a 2D platformer similar to Terraria, although I'm having some problems with some collision detection code. I'm using the code from the AppHub Platformer sample, but tweaked so it fits with ...
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### Dynamic bodies with Parallax Scrolling

I have an object that has a dynamic body. Currently, I'm setting it's position to follow the sprite when the parallax layer move. After a certain event, the object suppose to fall to the ground. That'...
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### Can you help with collision detection and response in a 3D car racing game?

I am trying to implement the collision detection and response in 3D car racing game. I have a car model, for collision I am assuming my car as a cuboid. my collision detection with walls is quite ...
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### How can I implement gravity?

How can I implement gravity? Not for a particular language, just pseudocode...
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### Perlin noise example the same on CPU as GPU?

I am looking for an example site with a Perlin Noise implementation in both CPU and GPU, that generates somewhat the same results in those two places. I see many CPU implementations of Perlin Noise, ...
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### How'd they do it: Destructible environments in BF:BC2 and BF3

How did the folks at Dice create the destructible environments in the more recent Battlefield games? Did they just assemble the buildings out of predefined sub-regions that break apart when there is ...
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### Momentum and order of update problems in my physics engine

This question is a "follow-up" question from my previous one, regarding collision detection and resolution, which you can find here. If you don't want to read the previous question, here's a brief ...
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### 2D physics library that supports curved surfaces and inverse or boolean shapes?

I've been using box2D for a few months, but I now badly need a physics library which can use boolean shapes (ie; cutting a circle out of a square) and/or curved surfaces. Does anyone have any ...
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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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### 2D Physics Engine for Platform Games - Riding on a Platform

I have a number of questions relating to using a 2D physics engine in a platform game, but one main one that I'm grappling with at the moment. I managed to somewhat integrate the Physics2D.Net engine ...
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### Implementing material deformation

I want to implement deformation of plastic material, like plasticine for example. Where should I start to study? What technique should I use? Thank you for any advice. EDIT I want to use it in real-...
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### Android Fling Gesture, Animation And Collision - Resources?

I'm starting work on a 2D Android game where the player will put their finger on a game piece and do a fling gesture to throw the piece across the gameboard. I've gone through some Android ...
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### How to handle physics of moving platforms in a platformer?

So after a few hours of searching on the internet, I have yet to find a pleasing answer on how to handle moving platforms in a 2d platform game. So I decided to make a simple prototype where you ...
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### 2D Spatial partitioning alternatives to spatial hashes and quadtrees

I've been trying to implement a spatial partitioning algorithm in my game, but both spatial hashes and quadtrees aren't what I'm looking for. My level size is not supposed to have a limit (only Int32 ...
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### Box2D Platform body not moving player body along with it

I am creating a game using Box2D (Javascript implementation) - and I added the ability to have a static platform, that is moved along an axis as a function of a sine. My problem is when the player ...
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### Where to start for implementing vehicle physics? [closed]

A little background for myself. I am relatively experienced with 3rd part physics engines such as Havok, Box2D, Bullet and have successfully integrated them in custom engine(s). I have also made a ...
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### Options available to a programmer on the Main Game Loop [closed]

Could someone please give me some insight into each one of the four topics listed below. I have a good idea about what passive and active rendering are, and that the use of active rendering is more ...
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### How to calculate falling and accelerating velocity?

I'm thinking of making a lander game, where you control a spaceship and need to land it without crashing. What is a simple formula to calculate speed of falling or acceleration with relation to ...
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### Are there well-known algorithms for fitting a polygon to an arbitrary shape?

I'm using the Chipmunk physics engine to make the levels for a 2D C game. I'd like to be able to fit a polygon to an arbitrary shape to serve as the collision mask. Given a black and white collision ...
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### Resources of realistic water simulation?

I want to study water simulation, with a a demo with source code which using physically-based methods(Eulerian approaches or Lagrangian approaches). How can I get some examples?
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### Physics for Android Game

I'm making a 2D game for the Android phone, one that involves falling balls. I want to use a physics engine to properly simulate the balls falling and hitting other objects. I'm currently using Phys2D,...
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### Collision response for 2D racing game

The title is fairly self-explanatory. I have a 2D racing game that utilizes per-pixel collision detection (the track is essentially two bitmaps, one for the graphics, one for collision data). The ...
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### 2D Platformer AABB collision problems

I have a problem with AABB collision resolution. I resolve AABB intersection by resolving the X axis first, then the Y axis. This is done to prevent this bug: http://i.stack.imgur.com/NLg4j.png ...
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### How could you parallelise a 2D boids simulation

How could you program a 2D boids simulation in such a way that it could use processing power from different sources (clusters, gpu). In the above example, the non-coloured particles move around ...
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### 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 ...