# Questions tagged [collision]

In collision detection problems, the challenge is to determine when shapes intersect each other.

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### What is wrong with this code, the collision detection is not working [closed]

Why does the code below not work. It is supposed to alert "kill" once a small circle hits the larger one. It uses the EaselJs library from the CreateJs suite of html5 coding tools. <...
2k views

### 2D Collision Detection in C++

I'm attempting to rewrite the classic snake game in c++. What I am inquiring about is my implementation for a 2D collision detection function. I am utilizing ...
9k views

### Line segment to circle collision algorithm

I've written a function (in Python 3) which computes if a line segment (constraint) and a circle (body) collide, and returns the point of intersection (closest point to the centre of the circle): <...
56 views

### Creating a maze game where the game resets if you hit traps/walls and finishes when you hit a different color

Here’s my code, the traps are the slightly visible squares. The user controls a red square (with arrow keys) and cannot touch the walls or traps or else the game resets. Additionally, if the user ...
178 views

### Calculate next position and velocity after “bounce”

Intro and code I have the following function that calculates an object's "next" position and velocity (in 1 dimension) given a boundary [0, max]. ...
287 views

### Collision detection method

I think everyone has some code they are embarrassed and not proud of and today I have decided to show mine. I'm not sure how to go about making this more efficient. At the time I was just happy it did ...
55 views

### Making a grid for collision detection in a game that wraps

I'm making a 2D game which wraps (when you move off the right edge, you appear on the left, etc). The game area is square, all objects are circles (with AABB smaller than the game area, and in most ...
141 views

### Simplify JavaScript collision detection with offset [closed]

I am working on a background project that is a little interactive. Now I am using some collision detection to draw some lines and stuff. The code I have works great but it is very bulky and hard to ...
415 views

### Bounding volume hierarchy

I'm building a bounding volume hierarchy in Golang. I can tell my code works because I did some test on it and it gives the same results as the brute force implementation (brute force is to test all ...
288 views

### C++ Breakout game using SDL

I did a big mistake to create procedural C++ breakout game on start and now im having trouble converting it into OOP. As far as I can see I need classes: Loptica (eng. Ball), Splav (eng. Paddle), ...
270 views

### Bounding volume hierarchy C++

Here is a C++ implementation of a bounding volume hierarchy, aimed for fast collision detection (view frustum, rays, other bounding volumes). It is based on the ideas from the book "Real-Time ...
274 views

### Javascript collision check

I have code to find images in my selections. But when nothing in selection (loop FOR) and selection is kinda big, it's kinda laggy. How can I improve my code? ...
3k views

### Find the intersect area of two overlapping rectangles

This is my solution to find the coordinates of 2 overlapped rectangles implemented in JavaScript. Each rectangle is represented by 2 points, each with 2 (x,y) coordinates. Can this code be improved?...
54 views

I'm making a simple 2D game engine, and to make collision detection more effective I tried making a QuadTree class. I don't know if this will work, but that's not that important. You don't have to ...
161 views

### Flood Fill using unordered_map which has user-defined type as key

I have an implementation of the flood fill algorithm. Assume that an image is provided as a vector of ...
367 views

### Collision detection for moving 2D objects

After implementing SAT (separating axis theorem) and not being happy with it only working on stationary shapes, this in theory allowing for fast objects to glitch through others, I came up with this ...
7k views

### Python Turtle based Pong game

I'm new to Python but I've coded in other languages mainly for hardware. I made Pong in Python using turtle but it's a little glitchy. I was wondering if any of you guys could check it out and give ...
40k views

### Overlapping rectangles

I received the following question in a technical interview today (for a devops/SRE position): Write a function which returns true if the two rectangles passed to it as arguments would overlap if ...
194 views

### Platformer Game: Arrow Key Player Movement and Collision Detection

I am in the middle of working on this game and I still need to add some things (e.g. score, coin counters, etc.) but I really feel like there is way too much unneeded code. Could you help me simplify ...
97 views

### Line and bitmap collision detection

I am trying to implement an efficient collision detection between a line joining two points and a bitmap mask. Example: Currently I am using Bresenham's line drawing algorithm to draw each pixel of ...
840 views

### Collision Detection in a 2D shooter game

I have the following code that works just fine for collision detection. The only problem is its size and its performance. I'm trying to do it and many other things 60 times per second, which doesn't ...
39 views

### Mutable 2d Rect class

So I wrote a 2d rectangle class for use in a 2d pygame based game engine. It uses the vector class from this question, so if you want to test, you need that code too. I want to ask: Does this ...
183 views

### OBBs intersection improvement for AABBs-OBBs

I'm trying to code some intersection codes for Oriented Bounding Boxes (OBBs) and axis-aligned bounding boxes (AABBs). I have the OBB-OBB intersection using the Separating Axis Theorem (SAT) and I'm ...
1k views

### Circle - Line segment collision

I wrote an implementation of circle - line segment collision detection algorithm. Here is quick demonstration how it works: And here is my implementation in Javascript using HTML canvas: index.html ...
140 views

### Weeding out triangles for triangle-triangle collision detection using a spatial hash

I am implementing a multi-phase collision detection system whose final collision check is checking the triangles of one shape against those of another. As the number of triangle-triangle comparisons ...
472 views

### Simple class game hierarchy with collision detection

I'm trying to make the transition from the 'understand how standalone features work' phase to writing.. more 'complex' code that could actually see use in real life, so I've been trying find some neat,...
84 views

### Clone of “Pop the Lock” iPhone Game

As an exercise, I decided to program my own version of the game Pop the Lock for the iPhone. The look and functionality are essentially the same, though the controls are modified for playing on a ...
421 views

### Octree Implementation

The fn_AABB struct represents an axis aligned bounding box, by a center(position) and half lengths(hwidth). They also contain a set of planes for use in collision but that is not important to the ...
506 views

### Computing intersections of a Polyline and a line

I wrote a script to compute / interpolate the nodes of a Polyline at a given latitude, input_lat. It works for my purpose but I am wondering if there is a better, ...
246 views

### Handling collision on a turn-based 2D game

I have implemented a collision check algorithm that I have created for my game, and the algorithm uses recursion. Now it all works fine, and I thought to myself, what if there was a way to solve this ...
158 views

grid.h ...
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Old code ...
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### Collision manager

I have a chunk of code that's working properly but it's way too complicated to read: ...
3k views

### C++ Erasing an object from vector of pointers

I am making this simple game in SFML and I have this vector of pointers std::vector<Brick*> bricks; which stores objects of class ...
362 views

### Maximize the number of PyGame sprites, with collision detection

I was trying to see what is the highest number of moving and colliding boxes (sprites) I could get in pygame? So that I could start working on game I want, I searched google and I found different ...
424 views

### Checking whether a bullet has hit a Space Invader

I just (almost) finished a Space-Invaders game in Javascript. I have a few bugs to clear out of the way but meanwhile I wanted to ask how I can improve the method I use to test if one of my 'Bullets' ...
237 views

### 2D Game - Ray-cast collision handling

This code is an excerpt from an infinite platformer I'm working on for fun. It belongs to the class GameObject from which every object i.e platforms, player, ...
1k views

### High performance, branchless Intersection testing: sphere-aabb & aabb-aabb

From my tests: AABB-Sphere: 2954.8 tests per ms. AABB-AABB: 1087.0 tests per ms. The sphere test is almost 3 times faster, but the two intersection tests seem to perform about the same number ...
6k views

### 2D Collision Detection

I wrote this a while ago but wanted to see if I went about it the right way and if my brain is working correctly. I was thinking about these two projects the other day and I recently released the ...
389 views

### Finding the nearest polygon

Finding the nearest polygon out of a list of polygons seems to be quite a challenge on performance, due to lack of optimization. Consider the following image: I'll give the concept behind this. The "...
28 views

### More JS AI causes slower AI movement in HTML Canvas

I have a simple little game with one character as the player and four enemy characters. I created a very basic AI, that moves towards the player when the player is nearby. That all worked fine, but ...
838 views

### Simple geometry problems involving rectangles and circles in Python 3

I'm working with some simple geometry problems featuring rectangles and circles. My code is as follows: ...
123 views

### Kattis “Hitting the Targets” utilizing a polymorphic relashionship

In order to learn C++ I have written a solution to this Kattis "Hitting the Targets" problem Basically the program is to accept some shapes (circles and rectangles) on std in and a set of points and ...
221 views

### Log collisions in generating unique random strings

I've created a small class to generate unique random strings. It works fine. I also want to log the collisions of the generated strings. I check if the generated string is in the array for uniquness: ...
207 views

### Collision detection accuracy

How do you guys think I can improve the code for collision detection on my website asteroidfield.eu5.org? The current code is ...
638 views

### Rectangle-segment collision detection

I am working with C++ and SDL, hoping to create a game later. I am implementing the collision detection between rectangles and segments. I found this (NateS user's solution) about line-rectangle ...
1k views

### 2D colliding disks in JavaScript (ideal billiard balls)

I am implementing a simulation of colliding disks (ideal 2D billiard balls) in JavaScript. I follow an event-driven algorithm that avoids discretizing time; the algorithm goes as follows at each step:...
64 views

### Find cells crossed by a line

This method find cells that are crossed by line A-B and adds them to one vector. I have got some duplicates here and some lines of code are very similiar but they differ in one variable. Should this ...