# Questions tagged [computational-geometry]

Computer geometry is a branch of computer science devoted to the study of algorithms which can be stated in terms of geometry.

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### Determining position of point W.R.T to given line equation

Problem from HackerRank:: Problem Statement: There are $N$ lines. Each line has an index between $1$ and $N$. The slope of each line is negative, i.e. it goes from upper-left to lower-...
1answer
294 views

### Generating vertices of the rectified hypercube

The following piece of code generates the vertices of the rectified hypercube in arbitrary dimensions. The 3D case of the rectified hypercube is a cuboctahedron with 12 vertices (±1,±1,0), (±1,0,±1), (...
2answers
888 views

### Find the largest area polygon built from a given list of vertices

This is code that gets a list of polygon vertices, non-ordered, and finds the order in which they should be arranged in order to create the polygon with the largest area. There are two key elements ...
3answers
541 views

### Check if 2 rectangles fit in another one, given their length and height

I was very intrigued with the manner to solve this problem. The program needs to know if 2 rectangles fit in another one, considering the lines of the 2 rectangles are always parallel to the other one'...
2answers
536 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 ...
2answers
401 views

### Grouping rectangles horizontally and vertically

As you can see the below code for each method is that same, except for the properties it uses. For example X vs Y and ...
1answer
1k views

### High performance triangle - axis aligned bounding box clipping

Implementation of a Robust (i.e. with a finite plane thickness) Sutherland–Hodgman algorithm for clipping polygons against an axis-aligned bounding box. I use the following code only for clipping ...
0answers
307 views

### Shortest bitonic tour

This a solution to the shortest bitonic tour using dynamic programming. Bitonic tour starts at the leftmost point then goes strictly rightward to the rightmost point and finally strictly leftward to ...
0answers
360 views

### Get vertical acceleration from rotation vector and accelerometer values

My goal here is to calculate the acceleration towards the ground, which I call "vertical acceleration". This seems to be working OK for the most part, except when there is a lot of rotation going on ...
2answers
73 views

### Find the best path amongst N random points

For an application with a graphical canvas, I want to generate N points. But then I want to link those points, and I want to find the best path through those points. I wanted to use a dynamic ...
0answers
791 views

### Computing intersection of 2D infinite lines

I wrote a small program to compute intersection of 2D infinite lines using Boost Geometry A line is defined by two points in Line class. The ...
1answer
59 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 ...
1answer
4k views

### Perimeter of a polygon given its vertices

I recently completed this code challenge so just looking for some feedback on my code. The task is to read polygon coordinates from a file and calculate the perimeter, I was provided with a script ...
2answers
572 views

### Convex envelope algorithm of random set of points

This is my "naive" implementation of a convex hull algorithm. By naive I mean that I am not using any of the advanced algorithms that exist to solve this problem. ...
1answer
521 views

### Template class for Andrew's Monotone Chain Algorithm Convex Hull

This is my first attempt at writing a template class. I am implementing Andrew's Monotone Chain algorithm, as described here to calculate a 2D Convex Hull. Since this is my first try at templates, I ...
2answers
14k views

### Point inside Polygon check

I have written a method to determine whether a Vector2 lies inside a polygon or outside of it. The polygon is defined by an array of clockwise vertices, p[]. It returns true if the point is inside, ...
4answers
684 views

### Striped closed poly-line

I'm working on class Striped_polyline which represents a closed poly-line filled with equidistant horizontal lines1: stripedpoly.cpp: ...
2answers
4k views

### Calculate the area of rectangles union

I've been given the following task: Given N rectangles with edges parallel to axis, calculate the area of the union of all rectangles. The input and output are files specified in program arguments. ...
3answers
2k views

### Given a set of points and pairs of lines, count the number of points that are between the pairs of lines

This is a contest problem. The entire description is here. In resume: The question gives a point simulating a light explosion that always has a negative x coordinate, a set of pairs line segments on ...
1answer
726 views

### Count number of isosceles triangles in a set of points

Given a set of points, what is the number of isosceles triangles that can be formed with the combinations of all points in the set? It is certain that 3 collinear points never exists in the set. <...
1answer
411 views

### Project Euler 91 (via HackerRank): Right triangles with integer coordinates

This is my code to solve HackerRank's version of Project Euler Problem 91: on an N × N grid, find the number of possible right triangles where one vertex is (0, 0) and the other two vertices are ...
3answers
7k views

### Checking if the point is on the line segment [closed]

Previously, I wrote the following code: ...
2answers
547 views

### Finding the maximum pairwise difference in a collection of colors

Note that this problem is equivalent to finding the longest line segment defined by any two points in a collection of 3D coordinates, which may be an easier way to visualize the problem, and is almost ...
1answer
356 views

### Graham scan implementation in Haskell

It looks like this is a really classical question, but I'd like to ask it one more time as all those solutions look quite long and complicated for me (maybe because I am dumb :) ) So this is a ...
1answer
2k views

### Drawing circles with triangles

As pyglet has no in-built method to return a vertex list of circle, I had to build one myself. This is a critical piece of code that I will use very frequently. I need it to be of very fine ...
1answer
83 views

### Remove “lines” from a 2D vec

I have some code here that I am very unhappy with. The task I am trying to accomplish is this. Given a 2d vec like this: [[0 2 0] [1 3 5] [3 3 0]] which can ...
2answers
4k views

### Python Trig Calculator

It's big, it's ugly, but it should work. My question is: how could I have implemented the "typeselection" function so it is less repetitive? Any tips on other improvements in coding style are welcomed ...
2answers
5k views

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5answers
819 views

### Segment Intersection — Failing on Unknown Edge Cases

I was recently at a programming competition. One of the problems was to determine whether two line segments are parallel, intersect, or do not intersect. For all of the test cases I ran, my solution ...
1answer
688 views

### Implementing Mitchell's best candidate algorithm

I have written an implementation of Mitchell's best candidate algorithm. Mitchell’s best-candidate algorithm generates a new random sample by creating k candidate samples and picking the best of k. ...
1answer
7k 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): <...
2answers
237 views

### Find non duplicate Triangle Triplets from a list of given numbers- version 3

It is a continuation of my previous question: Find non duplicateTriangle Triplets from a list of given numbers After I realized triplet structure using less space than ...
1answer
122 views

### Distance between angles as points

This code calculates the distance between angles, particularly for n-tuples of angles. One example where this situation occurs is as follows: I'm using a 2 arms, one 6 degree of freedom and the other ...
1answer
137 views

### Find non duplicateTriangle Triplets from a list of given numbers

I implemented an O(N^2) algorithmic solution but not sure it is better than my previous implementation Find Triangle Triplets from a list of given numbers in case of performance. I adapted almost ...
1answer
407 views

### Find Triangle Triplets from a list of given numbers

If a triplet of segments A, B and C are triangle triplets if and only if A + B > C A + C > B B + C > A Is there a better implementation for this problem? ...
1answer
2k views

### fftshift implementation for OpenCV

I'm trying to implement fftshift from matlab for OpenCV. Can you please review the correctness of my algorithm? Have I missed something? Also, is there a better and faster way to do it? ...
2answers
146 views

### Lazy properties for the angle and length of a line segment

The code below shows the pattern I use to manage properties in my classes when I have the following requirements: Some properties are slow to calculate and are rarely used, so I want them to be lazy ...
1answer
440 views

### Scale object based on distance between 2 vertices

I made this script so that I can scale objects for 3D printing from Maya. I had fun making it and I'm sure it could be cleaned up or improved. If it can be cleaned up please let me know. ...
2answers
218 views

### Comparing triangles using Java 8 streams

I'm trying to get more familiar with Java 8 streams as they seem to be very powerful (and shorter), so I rewrote a method to use streams. However I'm not very satisfied with it and would like some ...
2answers
880 views

### Speeding up 2D shadow algorithm

I wrote a class to represent a set of lights in a 2D game that raycast in order to find shadows. The draw method does a lot of calculations and takes a lot of time. Mainly, the adding of areas and ...
2answers
219 views

### Implementation of Graham Scan algorithm in Haskell

Here is an implementation of Graham Scan algorithm for computing the convex hull of a finite set of points: ...
3answers
285 views

### Line passing the most number of points

Given points on a two dimensional graph, find a line that passes the most number of points. Any comments please? ...
1answer
198 views

### Use of static factory methods for vectors and matrices library

I've been working on a Java-based mathematics library focusing on vectors and matrices. I plan to use it for an important upcoming project, so the classes are analogous to data types available in GLSL ...
1answer
448 views

### Tested cartesian plane utility

I am starting to explore automated testing of code, so I decided to write some trivial code about the cartesian plane and test it. I am particularly interested in automated testing conventions and ...
2answers
1k views

### Cubic “bezier” curve of grade n

This is code I wrote for calculating bezier curves as quickly and RAM efficiently as possible. I would like to know if there are faster ways to optimize anything, because I am very new to C++ and ...
0answers
172 views

### Graphical editor with geometric intersection

If it is possible I would like some comments on the overall style of the program. It feels like I am writing the whole program as one big script and I'm not sure how to break it down into several ...
1answer
318 views

### Ray→plane and ray→quad intersection

This checks the intersection between a Ray and a Plane and between a Ray and a ...
2answers
2k views

### Haversine formula in SQL

This is an implementation of the Haversine formula in Microsoft Transact SQL. How can I simplify the function? ...
2answers
261 views

### Quaternion rotations and preparing matrices for a shader

I am implementing an OpenGL ES 2.0 renderer in c. I want to use quaternions for rotations. Please take a look at the way I am implementing the rotation math. Everything looks as expected when the ...
1answer
94 views

### 'Tis the season for gift-wrapping

When reviewing a Graham scan convex hull algorithm implementation, I wrote the following function in an answer: ...