# 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.

75 views

### Controls: Rolling on a ceiling

Currently I'm writing an iOS game where the basic movement is rolling. Technically you make the player turn clockwise or counterclockwise. When you tilt the device to the right, you will rotate ...
239 views

### AABB vs Rectangle

I'm trying to wrap my head around 2D physics and stumbled upon Axis Aligned Bounding Boxes, and I have a couple of questions regarding them. In all AABB structs I could find out there, people prefer ...
103 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 ...
174 views

### very simple math destination and speed calculation

My player goes to (destinationX, destinationY) His position is: (x,y) and the player has an update event function update() { this.x = this.x + dx; this.y = this.y + dy; } what is the formula ...
892 views

### How can I determine trajectory from distance and time, without initial velocity?

I'm attempting to develop a Mortar that needs to lead it's shot to the target enemy. The shot will have a pre-determined constant flight time of (2.5 seconds) and it will have where the enemy should ...
342 views

### Why do my velocity estimates have such a large margin of error

I am writing a script in unity that applies a force to the object to advance it a set distance in an environment without friction or drag, producing a cosine force curve. However, as the target ...
199 views

### Collision Scenario, Detection and Response

I have AABB, BSphere, a Polygon Soup, a Triangle, a Plane, a Point and a Ray objects with a collision test that returns 'bool' if two objects collide or not. How can I use the above objects to ...
910 views

### bullet character controller sliding down any slope gradient

I've been experimenting with the btKinematicCharacterController. I've seen very old complaints that it has issues but I can't find anything recent stating that these issues remain (and nobody ever ...
248 views

### Tracing a 2d path through multiple gravity fields

For a projectile starting at origin O, an initial velocity V, and several stationary planets P[n], how would I pre-calculate and store the path it would take without actually stepping through each ...
160 views

### Lunar lander: why is my descent module crashing

I've been reading this awesome simulation of the actual Apollo 17 descent: http://www.braeunig.us/apollo/LM-descent.htm I've been trying to make my own simulation using Euler integration, with a time ...
292 views

### Using Geometric Slerp to move Camera

I'm writing a program in C++ using OpenGL and GLM; I'm trying to get my camera to follow my car. So far it successfully follows it around the screen, but I'm having trouble adjusting the Camera's ...
294 views

### How can I implement jumping in a 2D game using bounding box collision?

Problem: I'm trying to implement basic jumping to my 2D game engine, but have failed several times. Basically what I've done so far is disabling gravity and using a separate function moving the player ...
202 views

### Unit conversion for physics

I'm doing the physics for a 2D game which visuals are represented in openGl. Gravity is 9,8 m/s^2, how do i convert that to my screen size? OpenGl sets width to -1 to 1, and does aspect ratio of the ...
92 views

### How can I smoothly rotate a joint to an angle? [duplicate]

I would like to set the speed of my Box2D revolute joint on every update such that it rotates to a desired angle and stops. It should ramp down as its angle approaches the desired angle. My first ...
156 views

### Can not seem to adjust the speed of my Car

I'm programming in C++, rendering in OpenGL and using GLM for matrix/vector manipulation and I have implemented very (very) basic car controls; ignoring many forces that are present in reality. Since ...
213 views

### Farseer - Difference between Position, GetLocalVector, and GetWorldVector

I have used Box2D extensively, and am used to just calling body.GetPosition(). But Farseer does not have this. Instead it has a property Position, as well as methods GetLocalVector and GetWorldVector. ...
307 views

### Lunar lander: How to calc acceleration in each step

I'm trying to make a lunar lander simulator. I'm going to use a simple Euler integration. AFAIK all I've to calculate is the acceleration in each step, and then I should be able to update velocity and ...
629 views

### Make fast thing look slow (Box2D)

I'm working on a game that you control a trebuchet to throw balls to the opponent. It's like a game called 'Medieval Siege'. When the trebuchet is swinging its arm, player need to seize the best ...
3k views

### Basic Car Movement, Converting 2D Vectors to 3D problems

I'm trying to follow this guys method for steering a basic car. Link. It's the first example I can sort of get my head around and I'm trying to convert it to a working 3D version. To get some scope, ...
322 views

### Circle vs. Rect Collision accuracy problem

The blue ball is dynamic and is supposed to bounce off the walls, as well as the rectangle. Currently, the green rectangle is adding an invisible line to the scene, which doesn't let my ball go where ...
331 views

### Best collision shape for rooms

I'm wondering what is the most efficient collision shape to use with APIs like Bullet or Havok for rooms/interiors. Rooms tend to be boxes but are concave since the normals point inward which means no ...
125 views

### How to show the bow string stretching animation (?)

I was wondering how the animation in the angry birds of pulling the slingshot is done. One similar animation is available in this game but with a bow and arrow. I think both of them use the almost ...
669 views

### Making player movement direction follow players facing direction

if (controller.isGrounded) { moveDirection = new Vector3 (Input.GetAxis ("Horizontal"), 0, Input.GetAxis ("Vertical")); moveDirection = ...
318 views

### Block player movement

What do i need to keep my player model from going through environment objects like walls, trees etc? Im trying to figure out if should use rigid bodies and the built in physics but i feel that its ...
446 views

### 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 ...
2k views

### What is the point of “delta” in this code? Does it reflect a standard thing in game dev?

I know very little about game programming but would like to learn more. I am trying to understand the code for this game. I am trying to understand why the code is passing a "delta" to ...
140 views

### How to aim with a spaceship in 3D considering its angular momentum?

So I have a spaceship and I have 6 degrees of freedom. At a given moment the following vectors are known of the spaceship: Local forward. Local up. Local sideways (may be implied from the previous ...
155 views

### How to make “they need to be fed” movement style [closed]

This is the game for people who don't already know it: youtube video I am looking for theory about making an object move around another object and stay stuck to it. How would I implement something ...
64 views

### how to stop enemies from moving to one point when lots of them are chasing one object [duplicate]

i am making a top down game which lots of enemies are chasing one guy. then,enemies would move to one point without any collision,they just overlay each other. so ,is there any simple way to make ...
477 views

### Rope Colliding with a Rectangle

I have my rope, and I have my rectangles. The rope is similar to the implementation found here: http://nehe.gamedev.net/tutorial/rope_physics/17006/ Now, I want to make the rope properly collide ...
713 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 ...
2k views

I'm building a space exploration game and I've currently started working on gravity ( In C# with XNA). The gravity still needs tweaking, but before I can do that, I need to address some performance ...
105 views

### Box2D relations

As far as I know, the unit in Box2D is meters. When I use Box2D in Processing with JBox2D, I set the "world size" as the window size specified in the setup(). Now I'm wondering if there is any ...
151 views

### Correct order of tasks in each frame for a Physics simulation

I'm playing a bit around with 2D physics. I created now some physic blocks which should collide with each other. This works fine "mostly" but sometimes one of the blocks does not react to a collision ...
812 views

### How to handle jumping up a slope in a runner game?

In an 2D endless runner, what should happen when the player is running "too fast" up a slope and jumps? For example, in a "normal" case: .O. . __..O_____ . / . / O/ _/ If he is moving ...
516 views

### 2D game with 3D collision?

How do they do this bounce? Looks awfully complicated in 2D.
293 views

### How to manage sleep/awake state of physics body

I have a loop, which updates all the physics, inside the loop I'm updating the position of the objects, first thing is the gravity, which pulls all the objects to the bottom. Now my question is, how ...
1k views

### Do I need path finding to make AI avoid obstacles?

How do you know when a path-finding algorithm is really needed? There are contexts, where you just want to improve AI navigation to avoid an object, like a space -ship that won't crash on a planet ...
591 views

### Bouncing ball isssue

I am currently working on the 2D Bouncing ball physics that bounces the ball up and down. The physics behaviour works fine but at the end the velocity keep +3 then 0 non-stop even the ball has stopped ...
5k views

### Jumping with Mecanim synchronization

I am using Unity3D 4.1 for one of my projects. I have a robot character which is always running. I am using mecanim animation system. What I really want:When I press Space bar, the character should ...
131 views

### Adding Leniency to Jumping Mechanic

I have written some jumping code for my player in a platformer game. At the moment it has some basic logic which says that the player can jump if he is on the ground. The pseudocode looks something ...
184 views

### 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 ...
1k views

### The physics equation for a perpetual seesaw

I am trying to create a game that involves two or more people jumping on a seesaw and propelling each other in the air. I need help with the physics equations Assume no friction and no air ...
147 views

### How can I simulate a rigid body bounced from a wall in 3D world?

How can I simulate a rigid sword bounced from a wall and hit the ground (like in physical world)? I want to use this for a simple animation. I can detect the figure and the size of the sword (maybe ...
381 views

### Performing intersection testing in world's or object's space?

Am adding basic ray casting and collision detection for my game, also adding bounding volumes/collision mesh. Given that the ray is cast in world space and each mesh's node can track world ...
1k views

### Box2d making a body follow the mouse accurately

I am trying to make a box2d b2Body follow my mouse position. This is the code I am using at the moment but it is not performing very well: deltaPos = mousePos - body->GetPosition(); deltaPos *= k; ...
625 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 ...
164 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 ...
433 views

### Trouble with a modified parallax scrolling concept

I have a set of layers (each of them being a list of items) moving with different speeds as I mentioned here: http://stackoverflow.com/a/18962019/270197. Layers back in the scene move with slower ...
103 views

### How to reduce the time it takes to speed up an object?

I have a body that I am applying a force to every step. However, I it takes a significant amount of time for it to speed up, which I do not want. Is there some value I can adjust to help with this?