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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223 views

Box2D stable range and position

Box2D marks stable range of object size is 0.1M ~ 10M. This specifies object size range. How about space size? If I make an 1M object at (1000.0f,1000.0f) position? Is it can be stable? Or should I ...
4
votes
2answers
406 views

How to detect and collide two elastic line segments?

There are 4 moving physical nodes in 3D space. They are paired with two elastic line segments / strings (1 <-> 2; 3 <-> 4). Part I: How to detect the collision of two segments? Part II: On the ...
4
votes
1answer
767 views

Problem with box2d at beggining

I have problem with simple box2d physics: I have two bodies : 1 - static box , 2 - dynamic box. I only want to this dynamic box fall on this static, and lay. But now it looks like that at end , ...
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2answers
344 views

what is the name of the group of properties: position, velocity, acceleration, rotation

They say naming things is one of the hardest problems in computer programming, they were right. Given the pseudocode below, what is a more appropriate name for this collection of properties? Course, ...
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5answers
258 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 ...
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2answers
335 views

How to account for speed of the vehicle when shooting shells from it?

I'm developing a simple 3D ship game using libgdx and bullet. When a user taps the mouse I create a new shell object and send it in the direction of the mouse click. However, if the user has tapped ...
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2answers
1k views

Easiest Way To Implement “Slow Motion” and variable game speed in XNA?

I have an XNA 4.0 game that I want to be able to switch into slow motion and back again to full speed every now and then. So if you kill an enemy the game switches into slow motion as they explode ...
3
votes
1answer
466 views

How to bounce a 2d point particle off of a circular edge

In a prototype I'm building, a particle can spawn anywhere within a larger, confining circle. Important to note is that the particle will not spawn in the origin of the larger circle, but anywhere ...
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2answers
1k views

How to achieve smooth gameplay in a physics based multiplayer game? (2d)

I'm using cocos2d 2.0 and Gamekit for networking. I've got a server/client model. It works over wifi (local) and bluetooth. (Xcode 4.3, Objective C) Basically, there's a ball and 2 or more players. ...
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votes
1answer
901 views

Platformer Starter Kit - Collision Issues

I'm having trouble with my game that is based off the XNA Platformer starter kit. My game uses smaller tiles (16x16) then the original (32x40) which I'm thinking may be having an effect on collision ...
3
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1answer
490 views

Maximum range of projectile fired at given force and elevation

I've gone over this again and again, and my result is obviously wrong when viewed in-action. Here's the initial formula I converted (first one): http://en.wikipedia.org/wiki/Range_of_a_projectile ...
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3answers
1k views

Optimizing Bullet and ODE Physics on consoles and mobile phones

I'd like to use either Bullet or ODE on low powered devices (mobile and consoles), but the frame rates are below the acceptable 25-30fps for simulations. I've found that one articulated body by ...
3
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1answer
97 views

What is a collision shape?

I am a business developer who is new to game programming. In learning Stencyl, I see that there are things called collision shapes associated with tiles. This seems to be a standard term in game ...
3
votes
1answer
320 views

Fluid Particle Grid

So recently I have been looking at some fluid simulation techniques, specifically Smoothed Particle Hydrodynamics. One of the key components is a grid to avoid O(n^2) searches. I have been having some ...
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votes
3answers
313 views

Adding 'swerve' to a direction

I'm not much of a maths expert, so this is probably quite straight forward. I was playing a soccer flash game where you take free kicks. You provide Power, Swerve and Direction. I'm reading up on ...
3
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1answer
88 views

How do you prevent AABBs from passing through each other?

I know what an AABB is, but I don't know how you would check for collision with an object that is going really fast. If an object goes fast enough, it can skip over other bounding boxes without it ...
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4answers
1k views

Which Side Was Hit?

I am working on an Android game and I have two objects A and B (both rectangles) and when they collide I simply want to know which side of B was hit. I have detected the collision fine, but I am ...
3
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5answers
335 views

Forcing one projectile to follow close behind an initial projectile

I'm shooting out a projectile and I want another projectile to closely follow it. I can't simply shoot out the second projectile at a slightly lesser time because the first projectile may change ...
3
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2answers
88 views

Radiometric quantities and time in rendering

Often in papers people use various radiometric quantities, mostly radiant flux, radiant intensity, radiance and irradiance. It seems to me that all of these quantities are dependent on time. For ...
3
votes
1answer
211 views

GPGPU physics & game logic

I'm wondering about gpu accelarated physics after reading about Erwin Coumans presentation on GPU accelerated physics: http://www.gdcvault.com/play/1018185/GPU-Rigid-Body-Rigid-Body (demo video here: ...
3
votes
1answer
830 views

Engine for 2D Top-Down Physics-Based Skeletal Animation

I just watched at the Sui Generis video, and was completely amazed. Specifically, the part where the big troll thing is beating up the player with his flail. This got me really excited, and I would ...
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votes
4answers
3k views

2D Collision in Canvas - Balls Overlapping When Velocity is High

I am doing a simple experiment in canvas using Javascript in which some balls will be thrown on the screen with some initial velocity and then they will bounce on colliding with each other or with the ...
3
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1answer
3k views

Creating sideways friction in a 2D top down racer

I've been playing around with trying to create some kind of top down racer but I'm having trouble getting the car to turn properly. At the moment this is the code I have to update the position of the ...
3
votes
1answer
278 views

Why does my ball always bounce perpendicular to walls?

I'm using Box2D. I think it's something to do with wall's fixture definition, but when a ball goes toward a wall at a 45 degree angle, I would expect it to bounce off at 135 degrees, but it always ...
3
votes
2answers
998 views

Jumping Vs. Gravity

Hi i'm working on my first XNA 2D game and I have a little problem. If I jump, my sprite jumps but does not fall down. And I also have another problem, the user can hold spacebar to jump as high as he ...
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3answers
356 views

Collision filtering techniques

I was wondering what efficient techniques are out there for mapping collision filtering between various bodies, sub-bodies, and so forth. I'm working on a physics engine and I need ways for a user to ...
3
votes
1answer
726 views

Angular Velocity

Hey, I have a particle that is hit with a force F at a particular position on the ball P. How can I calculate the angular velocity of the X,Y and Z axis? The actual rotating of the object should be ...
3
votes
1answer
284 views

Approximating walking physics via simpler sliding physics

I am modeling walking insects. I implement them as cuboids and use forces (including friction and drag), to control motion. However, the movement characteristics of this 'sliding box' physics don't ...
3
votes
1answer
167 views

Car physics - velocity and latheral force

Im developing simple car racing game. To turn a car, I need to calculate slip angles for each tire and then use those angles to find lateral force (using Hans B. Pacejka magic formula). One thing I ...
3
votes
1answer
221 views

Simple 3D collision detection for general polyhedra

I have correctly set up a SAT system. I now need to determine a simple, fast, and general purpose collision detection mechanism to identify the collision points. These points will then be used to ...
3
votes
3answers
196 views

Scaling Sound Effects and Physics with Framerate

(I'm using XNA and C#) Currently, my game (a shooter) runs flawlessly with 60 FPS (which I developed around). However, if the framerate is changed, there are two major problems: Gunshot sound ...
3
votes
1answer
959 views

AndEngine: Density, Elasticity, Friction, Gravity concepts

I am new to AndEngine. I have seen some physics examples from AndEngine Example package. I want to know the role of density, elasticity, friction and gravity while implementing physics. How they ...
3
votes
1answer
479 views

Making particle bounce off a line with friction

So I'm making a game and I need a particle to bounce off a line. I've got this so far: public static Vector2f Reflect(this Vector2f vec, Vector2f axis) //vec is velocity { Vector2f result ...
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votes
1answer
507 views

Calculating torque required to turn an object to a target rotation, depending on timestep

The function below works fine, when the timesteps of the physicsengine are short enough for the function to update often. It determinates when the ship(the object) needs to start decelerating to reach ...
3
votes
2answers
212 views

What is a fair latency, to cut off game connection at?

I'm currently coding a realtime game. I'm doing alot of technical operations with the physics world (resimulations of old world states etc.) to prevent game lag. I save the world state every physics ...
3
votes
2answers
499 views

How to achieve realistic fake physics?

In my opinion, games that are most entertaining to watch and play implement fake physics, the difficult issue is how to implement the fake physics and still allow it to appear realistic. Most popular ...
3
votes
1answer
57 views

Inertia Tensor and World Coordinate conversion

I understand that the inertia tensor is basically a 3x3 matrix. I'm modelling a cube, and the inertia tensor for this shape has values for moment of inertia on the main diagonal of the matrix. All the ...
3
votes
2answers
259 views

When to detect and respond to collisions?

I've usually implemented collision detection like this in the past: Move entity Check if it collides with anything Resolve the collision by moving it back That's also the approach employed by most ...
3
votes
1answer
302 views

How to emulate knob turning, based on x/y movement?

I'm doing a game where one component is that you turn a knob. I'm having trouble getting good "knob behavior". I know the current touch/mouse X,Y location, and I keep track of the previous X,Y ...
3
votes
4answers
2k views

How to move a sprite automatically using a physicsHandler in Andengine?

I use a DigitalOnScreenControl (knob with a four-directional arrow control) to move the entity and the entity which is bound to a physicsHandler. physicsHandler.setEntity(sprite); ...
3
votes
1answer
193 views

Simulate 'Shock absorbtion' with tire rubber in PhysX (2.8.x)

This is a kinda tricky question and I fear there is no easy enough solution, but I figured I'd hit SE up before giving up on it and just doing what I can. A machine I am working on has no suspension ...
3
votes
1answer
216 views

Framerate control and physics engines?

I am reading this article on how to control the framerate and physics calculations. But in the game I am writing, I use a third party physics library and the only thing I do to update my physics is ...
3
votes
1answer
243 views

What are the advantages of having a real time based physics? [duplicate]

Possible Duplicate: Fixed time step vs Variable time step Now just let me clarify what I mean by "real time based physics", which I will call RTBP from now on. Well, basically, it implies ...
3
votes
1answer
607 views

What is a CPU-efficient cloth simulation technique for a 2D game?

Are there techniques for simulation of cloth and hair in an efficient (in other words, not too CPU-intensive) manner? I only need to calculate the key points as the drawing will be done in 2D.
3
votes
1answer
162 views

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 ...
3
votes
2answers
1k views

3D Ball Physics Theory: collision response on ground and against walls?

I'm really struggling to get a strong grasp on how I should be handling collision response in a game engine I'm building around a 3D ball physics concept. Think Monkey Ball as an example of the type ...
3
votes
1answer
589 views

Breakout clone, how to handle/design for collision detection/physics between objects?

I'm working on a breakout clone, and I wish to create some realistic physics effects for collision - angles on the paddle should allow the ball to bounce, as well as doing curve balls etc. I could use ...
3
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1answer
195 views

Follow point of interest by applying torque

Given a body with an orientation angle and a point of interest or targetAngle, is there an elegant solution for keeping the body oriented towards the point of interest by applying torque or impulses? ...
3
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2answers
430 views

Unity 4 - Some Rigidbodies Won't Fall Asleep

I'm having this problem in the free edition of Unity 4.1 where rigidbodies aren't falling asleep (and yes, I've tried playing with the sleepVelocity and sleepAngularVelocity values!). I've read the ...
3
votes
1answer
183 views

Is it possible to get the colliding sides using the separating axis theorem?

The title says it all, is it even possible to get the colliding sides? I'm checking for collisions between two OABBs, which works fine using SAT. Now I want to set the moving object's velocity to the ...