# Questions tagged [collision-resolution]

A process of adjusting game objects position after collision.

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### How can I calculate the initial velocity of a cue ball after hitting it with a cue stick?

I'm currently building a billiard game, and I'm faced with the following problem: A cue ball is hit with a stick at an angle equal to Θ. Given that the stick is hit at the exact center of the ball, ...
623 views

### How do you make a particle system collision add a force to an object towards the particle system?

I have a lightning particle that gets shot at the ground. I want the particles to collide with the object they hit and add an upward force. I tried just entering a negative force in the Collider Force ...
285 views

### 2d side scroller slope physics and collisions

In old 2d games such as double dragon, streets of rage etc. where the player could move “up and down” on the y-axis to give an illusion of depth (as opposed to something like Mario) how were slopes ...
336 views

### Terrain collision with sphere and OBB

I'm implementing my physics engine for my 3D game. So far I've been able to implement collision detection between OBB, spheres and planes. The engine generate contacts and resolve them with an ...
925 views

### AABB to AABB collision response

I am currently trying to resolve collision between two AABBs. I already have a function that can detect if the the two boxes are colliding and returns true if the two boxes are colliding. The problem ...
142 views

### How to allow to slide rectangle to not colliding with corners between two rectagles?

I am detecting each side of collision between two rectangles, and wen I collide them, lets say, with the left side, it also detects collision on the top side when I move to the top, and the downside ...
185 views

### How to use separating axis theorem to allow for sliding along walls

I'm making a 2D platformer game and using the separating axis theorem for collision detection, but I want the player to be able to walk along the ground and slide on walls and other stuff and I can't ...
152 views

### How can I get visually accurate collision normals with sphere collisions?

I'm solving simple 3D sphere collisions by checking the sphere for overlap with a mesh, finding the nearest point on that mesh's surface to the center of the sphere, and then resolving the collision ...
230 views

### Enemies overlapping

I have a simple WebGL maze game and has problem with enemies overlapping when they are going to target position. Now i'm detecting there collisions, but dont know what to do with them when they are ...
84 views

### Subtracting magnitude from 2D circle contact

I'm trying to create an agar.io clone. In agar.io, each player can have multiple cells that "chase" the mouse pointer. The cells can also have multiple masses and the velocity is tied to the mass. The ...
3k views

### 2d Rectangle Collision Resolution

My Journey... I've long struggled with rectangle to rectangle collision resolution. I've been making games for almost 10 years and still have yet to find a foolproof, reliable strategy. When doing ...
318 views

### Finding the contact point of two spheres

Is there a way to get the normal and depth of two spheres that have collided. I know that it is something to do with the center and radius of two spheres but I am not sure what
310 views

### How do I get an aabb's collision normal [duplicate]

I have two aabbs and I need to know the collision normal of the to help me slide the aabbs across themselves. I have searched google but nothing really came up. How do I get the collision normal of ...
136 views

### Resolving Circle-Circle collision

If you have a stationary circle with radius x, and a moving circle with radius y, when a collision is detected, how can you resolve the collision, such that the moving circle stop? I.e. What would be ...
958 views

### Unity3d physics stability with low fixed timestep

I'm developing a vehicle simulator game for mobile platforms. This vehicle has some hydraulic arms. I use hinge joints and configurable joints. There can be collisions to walls etc. When I set a low ...
58 views

### How to resolve collision of two or more linearly moving non-rotating axis-aligned 2d boxes?

Sorry for my bad english. In my game, to resolve collision of a moving-box (e.g. the player) and fixed-boxes (e.g. tiles) :- I check in advance whether a moving-box is going to collide with a ...
263 views

### Calculate bounce and friction after a projection-based collision

According to the N Tutorials, after a projection-based collision (i.e, adding a minimum translation vector to an object's position in order to bring it out of collision), bounce and friction are ...
308 views

### Impulse resolution for purely rotational collisions (relative linear velocity = 0)

I've been writing a basic physics engine, (loosely) following Randy Gaul's online tutorial. I have been using this equation that he derives: j=\frac{-(1+e)((V^A-V^B)*t)}{\frac{1}{{mass}^A}+\frac{1}{...
85 views

### Why are my shapes teleporting to the center of the map?

I am making a Diep.io Clone, and everything was going smooth until I made a collision resolution system for when a shape collides with another shape. Instead of them bouncing off of each other, they ...
61 views

### High level overview when handling collision detection (or resolution) with overlapping when already touching

I'm looking for some advice on handling collision detection when you've already collided (at a high level). Suppose we're using 32-bit floating points, but with the constraint that the entire level ...
392 views

### How could I implement collision resolution with MonoGame

I'm building a game engine (for learning and self-development purpose), and I'm starting implementing collision resolution, I already have the collision detection part but I cant' find any good ...
119 views

### When should you check collisions?

Suppose a basic game with several circles drawn to screen. The user can select and drag any ball and move it around the screen. Should the selected ball overlap with any other ball on screen, the ...
153 views

### How to Prevent Sticking to Overhead Slopes

I am having an issue with overhead slopes in my 2D platformer. I implement slopes using a LineSegment class. My player sprite has a spine attribute which is just a line segment from the midtop of his ...
105 views

### How to implement wall-following behavior?

I am working on an action platformer and am trying to implement an enemy with simple wall-following behavior. I want the enemy to follow the boundary of whatever connected constellation of walls it is ...
377 views

### Resolving collision with multiple objects

I already have SAT implemented for collision detection and MTV computation and it works totally fine when my character collides with only one object. But it's possible that there is a collision with ...
410 views

### 3D Coulomb Friction - Use Collision Impulse To Calculate Friction Force?

I've been using this document to learn how to implement a very basic physics engine. The section on Coulomb Friction on page 55-56 (marked as pages 43-44) confuses me. It observes that the friction ...
41 views

### Weird issue in collision resolution of non-static bodies

I'm a bit of a beginner in engine development, so I decided to write my own engine from scratch so I could learn more about what happens under everything. I've been progressing fairly well, except ...
563 views

### 2D physics engine: Impulse based collision response with contact point manifold

I'm implementing a 2D physics engine where collision response is based on impulse computation. I'm going to first expose the context, then the problem, and finally the questions. Context Simple ...
62 views

### Selective Collision Resolution While Rolling

I am working on a 2D action platformer in Pygame, though my question is a general one. The question concerns selective collision resolution. In short, I want certain collisions to be ignored while my ...
507 views

### Calculating collision of polygons

Say I have a multitude of 2D polygons floating about on a plane. These polygons can have any side count and aren't necessarily regular. Assuming I know absolutely everything about the polygons (area, ...
165 views

### Jitters in collision reaction

I'm working on a project for school and I'm having some trouble solving a bug. When the player collides with a rectangle the sprite/hitbox keeps jittering while the player has momentum in the ...
7k views

### How can I detect the player being crushed in a 2D platformer?

I'm checking collision for a platformer character as shown in #1. The red dots are the pixels that are checked and the grey lines indicate the axes they pertain to. I like the results I get from ...
921 views

### Collision Resolution of Axis-Aligned Bounding Boxes that Change Size

I am developing an action platformer in Python, with Pygame. That said, my question is a general one about collision resolution strategies. I use an axis-aligned bounding box for the purposes of ...
96 views

### Collision stickyness problem on multiple inputs

I've been trying for a couple of days to solve an issue I'm having with top-down 2D collisions, whenever I collide with tiles that have adjacent collidable tiles my player sticks to the wall, If I ...
348 views

### Why is my sliding AABB collision acting strange?

I'm working on a Minecraft like game engine and recently I've been trying to add good collision response which I have kind of. The collision response is perfect when I try and go through the right ...
114 views

### In what order should collisions be resolved?

I am creating my 2D game engine and I need to know if I should first move all objects and then resolve collisions with all objects or I should move and resolve collision one by one objects.
258 views

### How to get a translation vector in a certain direction? SAT

I'm using the seperating axis thereom for discrete collision detection. I have code to find the minnimum translation vector (or distance) to seperate two shapes but how can I adjust it to get a vector ...
143 views

### 3d complex collision and trigger detection [closed]

I'm a Unity developer and I use monobehavior functions to dot things like collision detection. I have read about articles about collision detection. Most of them work with geometrical structures like ...
153 views

### How to make top-down AABB collision response work properly in MonoGame?

I have a problem with top-down racing game I'm working on. I need to implement AABB collision with other cars and objects. But when going fast enough, the car can go through thin objects when hitting ...
186 views

### Collision avoidance not only AI wrong

I am trying to implement the game similar to Dota 2 or Warcraft 3. I want this: when user clicks the right mouse button I want to navigate to the click position. However if there is an obstacle in my ...
43 views

### If collision move around the collider

I am writing a game in Java, I have this long method to move GameBodyObject towards the point: ...
480 views

### game physics: contact constraint and relative velocity

For two rigidbodies (2D boxes), A and B, I have been colliding A with B and finding the collision normal pointing towards A i.e. the direction that would separate A from B. When it comes to ...
65 views

### collisions: How to handle contact constraints for a rigidbody constrained to a line segment

I'm trying to come up with a strategy to handle a situation in 2D, where a rigidbody moves along a straight line segment, and can collide with other similar bodies and also static tiles. A naive ...
91 views

### How to detect and prevent the resolution of fake collisions?

I'm creating my own physics engine and I came across a small inconvenience. Here how it goes: when a body tries to push into something it really can't push, it gets pushed back (which is completly ...
766 views

### Physics engine and squishing of stacked objects

I have a general question that seems to apply to most physics Engines (Box2D, Unity, Matter.js, …). I'm trying to make a tower of rectangular objects that are stacked on the [static/mass=infinity] ...
188 views

### Polygon-Circle Collision Algorithm not working

EDIT: Updated code and video I've been working on one of the last pieces of my collision detection system for my game, a polygon-circle collision method. I'm almost there with it, but there's a few ...
168 views

### Issues with player movement and character interaction within Pygame

I am working on a small game that deals the main character, which is a cat, and dogs that chase it. The dogs are able to wander around like they are supposed to do, but the cat will only move a small ...
393 views

### Rigid body falls through static mesh even though collision is detected

I'm using Jitter Physics to create a game. For testing, I have ball (a spherical rigid body) falling onto a small box-like mesh. The problem is that the ball falls straight through the floor, even ...