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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4
votes
3answers
225 views

How do I resolve a sphere-triangle collision in a given direction?

I am trying my hand at game physics. I understand that the basic way to pull back a sphere when it collided is to negate the penetration distance: // If collided... // `distance`: distance form ...
1
vote
0answers
34 views

PhysX - Revolute joint around unit vector

I'm using a right-handed coordinate system with (0,0,-1) = forward, (1,0,0) = right and (0,1,0) = up. PhysX version is 3.3.0. I have a unit vector which represents the axis around which my actor is ...
3
votes
2answers
139 views

Why are my Box2D wheels slipping on ground?

I have a car, set up in Box2D as a rectangle connected with two wheels using WheelJoints: The wheels are defined as follows: FixtureDef wheelFixtureDef = new FixtureDef(); ...
0
votes
0answers
35 views

CCTextField won't appear

I can't seem to add a CCTextField in my physics node, I tried all different methods, but it's still not happening. Here's my code: CCTextField *tf = [[CCTextField alloc] init]; tf.contentSize = ...
0
votes
2answers
195 views

How to add a constant horizontal force just like gravity?

I want to add a constant horizontal force, just like gravity to a projectile or a sphere moving in 3d space, which will make the projectile or ball or sphere or whatever be influenced by this force so ...
3
votes
1answer
123 views

Unity's default integration method

Which method(s) does Unity provide for physical integration? RK4? Verlet? Euler?
0
votes
3answers
199 views

What is the easiest way to make an object follow the edge of a sprite?

I have a rounded rectangle sprite and another sprite that's just a circle. I want the center of the circle to follow the edge of the rounded rectangle. Is there any easy way to accomplish this task? ...
0
votes
0answers
67 views

Box2D collision damage calculation from postSolve or not?

I'm using postSolve to get impulse then calculate damage base on that impulse. But there's some issue: Stability The damage isn't stable. When the same ball is hitting with same speed, the damage ...
6
votes
1answer
138 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 ...
5
votes
1answer
151 views

Self colliding cloth physics

I've previously simulated cloth using Verlet integration but couldn't successfully get the cloth to collide with itself in an efficient way. The reason being is because I used a brute force algorithm ...
2
votes
1answer
99 views

Is there a way to view all colliders in a unity project at runtime (after the game have been deployed)?

I'm have created a small Unity project but physics has weird behavior (bug). Unfortunately it only happens on some specific hardware (after build), not on development machine. I don't know what is ...
0
votes
1answer
140 views

Bullet 3D Physics Objects Not Rotating?

So I've got Bullet 3D controlling the motion of objects rendered with DirectX. In the clipping below I've got 2 identical rectangles & 5 balls. The lowest rectangle has a mass of 0 and doesn't ...
2
votes
2answers
54 views

How can I add an impulse to specific rigid bodies at rest?

Scenario Rocks falling down a rocky slope, with a flat surface at the bottom. When they land on the surface, the rocks move slightly before coming to a rest. GLESDebugDraw shows the bright orange ...
0
votes
1answer
46 views

How to resolve OBB collision penetration?

I would think this is a common issue, but I couldn't find an answer that helped me. Help would be appreciated. In my game I have rectangular objects. They have rotating bounding box, aka not AABB but ...
0
votes
1answer
51 views

How can I avoid type checking in the physics side of collision handling?

I have a class responsible for handling the physics side of collisions. When the collision detector spots a collision, it notifies both entities in the collision to take care of gameplay. It also ...
1
vote
1answer
34 views

Forces on entities: remove all each update step, or remove on demand?

Following the answer to my question here, the way I apply forces on an entity, is each entity has a Map of forces (Vectors) and their IDs. Every update step, the acceleration vector is set to the sum ...
5
votes
2answers
240 views

How can I synchronize ocean waves over the network?

I've been performing a little bit of research in my spare time on ways to increase the interactivity of environments in a networked game or simulation. One of my areas of research is fluid-dynamics ...
2
votes
2answers
126 views

How to correctly implement player acceleration caused by player input

In my game I implement movement in the Player class like so: // called from Player's update() method, which is called from the gameloop. void move(){ velocity.x += acceleration.x; velocity.y ...
1
vote
1answer
88 views

2D how to add graphics for liquid physics?

I was always wondering how to add the graphics to a a blob body for example, regardless of what engine or library you are using, i want to know (theoratically) how to move from this state : ...
0
votes
1answer
44 views

Accelerated Motion

I'm making a menu for my game with SDL, when you click on an option a sub menu slides down and is shown, just sliding down is really boring, so I want it to accelerate(like if gravity was pulling it) ...
1
vote
1answer
182 views

Unity: Rolling a ball around a spherical planet with forces

I'm trying to make a game in Unity where the player character is a ball (a sphere), and the game world is a planet (a very large sphere) that the ball can roll around on. The ball can be rolled in any ...
0
votes
2answers
122 views

Without using a pre-built physics engine, how can I implement 3-D collision detection from scratch? [closed]

I want to tackle some basic 3-D collision detection and was wondering how engines handle this and give you a pretty interface and make it so easy ... I want to do it all myself, however. 2-D ...
5
votes
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 ...
0
votes
1answer
104 views

Resolution independent physics

I'm making a game like Doodlejump but don't know how to make the physics scale on multiple resolutions. I also can't find anything related to this on Google. Right now I'm scaling the game using ...
1
vote
1answer
70 views

Reflection velocity

I'm trying to get a moving circular object to bounce (elastically) off of an immovable circular object. Am I doing this right? (The results look right, but I hate to trust that alone, and I can't ...
1
vote
0answers
43 views

Bullet Physics ConvexDecomposition?

I've looked at Bullet Physics ConvexComposition Demo and would like to implement that in my game but the code is so undescriptive and it's hard to understand what is going on. Would any of you people ...
0
votes
1answer
43 views

Inertia in flight simulation using box2d

I'm trying to simulate flight using box2d and libgdx. The main problem I am currently experiencing is with inertia: since there is no air, the plane looks like it were drifting. I wasn't able how to ...
0
votes
1answer
80 views

Load Meshes with Bullet Physics

I just started implementing some physics in my game with Bullet Physics and I was just wondering how would i use bullet physics to load in meshes. For my for DirectX I load in x files into a ...
5
votes
1answer
513 views

Unity falling body pendulum behaviour

I wonder if someone could provide some guidance. Im attempting to create a pendulum like behaviour in 2D space in Unity without using a hinge joint. Essentially I want to affect a falling body to ...
34
votes
3answers
7k views

Why do we use the Pythagorean theorem in game physics?

I've recently learned that we use Pythagorean theorem a lot in our physics calculations and I'm afraid I don't really get the point. Here's an example from a book to make sure an object doesn't ...
4
votes
2answers
1k views

Why isn't this physics code scaling velocities separately?

I'm working my way through this book and I'm trying to work this code out: var squaredVelocity = this.velocity.x*this.velocity.x + this.velocity.z*this.velocity.z; if ...
0
votes
1answer
105 views

Making particles accelerate toward a mouse point

I'm currently working on a particle simulation program that makes pixels move towards a mouse point continually accelerating, but i'm running into some math issues. Currently my particle will ...
1
vote
1answer
153 views

Spaceship acceleration for following waypoints

I'm creating a turn based space ship strategy game with simultaneous turn resolution similar to Steam Birds. After all the orders are given, the ships run through a real time simulation where they ...
0
votes
0answers
123 views

Realistic collisions with a kinematic rigidbody?

I have a car game where player drives a car; this car has a collider and a kinematic rigidbody attached and is completely controller by script (i.e. a script sets its position and rotation). In the ...
22
votes
6answers
2k views

How can I Intercept object with a circular motion

I am creating a 2d space game and need to make the spaceship intercept a planet. I have working code for straight line intercepts but cannot figure out how to calculate the planets location in a ...
1
vote
2answers
112 views

Unity - Across the wall

I have a problem here. I animated my main character and is working. It walks run and jump however it goes across walls and ground. As in every single video I watch in unity tutorials I put a ...
6
votes
1answer
301 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. ...
3
votes
3answers
321 views

Throwing a ball and estimating its path using a Physics engine

The problem: A player entity wishes to throw a ball from a known position with a known initial velocity. The surrounding environment contains physical objects that can alter the trajectory of the ...
1
vote
1answer
51 views

How to convert strict limit in position into gradual slow down?

The player moves a spell object, the spell must stay withing a certain range of the player. The spell is moved using a physics system and it has mass and velocity. Currently when the spell goes out ...
0
votes
2answers
470 views

Libgdx: movement of scrolling background is not smooth even at 60fps

I'm developing a game and I want to make a sliding background. The background is not scrolling smoothly. I logged the fps, but it was ok. This is my code, I don't know what I'm doing wrong, any ideas? ...
0
votes
0answers
145 views

How do I combine multiple squares into one Tetris block?

I am learning Phaser by making a simple game—Tetris. I'm having difficulties: Can I use simple rectangles as tetrominoes or they should be sprites? I don't know how make the figure's block ...
0
votes
2answers
157 views

Integration error in high velocity

I've implemented a simple simulation of two planets (simple 2D disks really) in which the only force is gravity and there is also collision detection/response (collisions are completely elastic). I ...
1
vote
1answer
173 views

How can I unify the collision handling of melee/spell attacks in a networked environment?

I am trying to figure a good way to create the battle system of a game. The game is fast paced and the gameplay needs to be precise (think hack n slash) What I would like to achieve is a simple and ...
0
votes
1answer
132 views

Having issues with pong physics, is my approach wrong?

I've been working on a pong clone, i've made games in the past but they have all been very hacky. This time I was trying to go for a better approach in terms of using OOP or patterns. So far the games ...
1
vote
1answer
140 views

How to correctly handle multiple movement key presses resulting in double the speed?

I am trying to implement acceleration and drag into my top-down 2D game. The player can move using the WASD keys. Acceleration works fine, but the way I handle the directional velocity causes the ...
2
votes
1answer
179 views

How do I make a sprite appear to sway with the wind?

I'm trying to find a method to simulate the effects of wind on various sprites in a side-view 2D scene. What relatively simple technique could I use for this? What I have in mind is to give these ...
0
votes
1answer
79 views

How long does the collision take?

I want to simulate a simple force-acceleration (rather than impulse-velocity) physical world made up entirely of disks and I'm having an irritating problem with my physics. When two disks collide, I ...
-3
votes
2answers
131 views

what is the ducking ability? [closed]

In my game framework I have this property: canDuck : Boolean = true Determines whether or not the hero's ducking ability is enabled. What does it mean ? regards
2
votes
2answers
138 views

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 ...
0
votes
1answer
159 views

Determine speed of sprite

I'm trying to calculate the speed of my sprites in Cocos2d but I'm having some difficulties. I'm not sure which units of time/speed cocos2d uses. My background sprite moves 2 positions to left each ...