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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2
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0answers
25 views
Ray→plane and ray→quad intersection
This checks the intersection between a Ray and a Plane and between a Ray and a ...
2
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2answers
37 views
Haversine formula in SQL
This is an implementation of the Haversine formula in Microsoft Transact SQL.
How can I simplify the function?
...
6
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2answers
83 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 ...
6
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1answer
39 views
'Tis the season for gift-wrapping
When reviewing a Graham scan convex hull algorithm implementation, I wrote the following function in an answer:
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7
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3answers
61 views
Checking for intersection points
The aim of the program is to find those points which comes under the intersection of at least 2 circles.(space is a 1000x1000 matrix)
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8
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1answer
250 views
Jarvis's March Convex Hull
I'm more concerned about the coding best practices and how it's written here than the actual algorithm and math. I'm concerned about stack constraints, passing arguments,..etc. If there is anything ...
4
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1answer
92 views
Generate sample coordinates inside a Polygon
I have a Polygon named as poly. I attempted to randomly select 5 coordinate points that lies inside the polygon.
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7
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1answer
72 views
2D Convex hull exercise
I'm reading Real World Haskell, and this is my first try with the language.
This is the result of the exercises of chapter 3:
Consider three two-dimensional points a, b, and c. If we look at ...
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0answers
74 views
Optimize QuadTree to find K Nearest Neighbors
I'm looking a way to make my k nearest neighbors search more efficient. The context of the question is that I'm given a list of topics that have a unique ID (integer) and a (x,y) coordinate (floats) ...
3
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1answer
70 views
Calculating the distance squared between all vertex-pairs of a number of 2D polygons
I have implemented my code using Cython. It is the current bottleneck in my computations.
There are two non-numpy functions involved:
calculate_2D_dist_squared ...
11
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2answers
202 views
CodeEval's SkyScrapers challenge
This is a solution to CodeEval's SkyScrapers challenge.
You are given a list of triples \$(l, h, r)\$. Each triple represents an axis-aligned rectangle, with top-left corner at \$(l, h)\$ and ...
14
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7answers
622 views
Custom mathematical vector class
My first bigger C++ project: a vector class for personal use and statistical computation.
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-1
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1answer
135 views
Custom 2D/3D Graphics Vector Classes vs SFML's
I don't really like SFML's Vector Classes so I tried making my own. Any criticism is welcome.
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8
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6answers
1k views
C++ 3D Vector Implementation
I have been learning C++ now for 2 months and this week I started reading a book on 3D graphics. I like coding whatever mathematical stuff I learn so I can understand it better, so when I learnt about ...
6
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1answer
106 views
3D matrix rotation in homogeneous coordinate space
Assuming that the framework is in place to handle the difference between row and column major matrices, I am curious to know if in a header based library such implementation is semantically and ...
2
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1answer
96 views
Neighbours from point connections
I am working with a mesh of triangles (in 3D, although I doubt it makes a difference). The mesh is given as list of lists, each list containing the indices of the three vertices of a triangle in said ...
13
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2answers
278 views
Detecting Two Intercepting Circles with editable x, y, and radius in JavaFX
I was actually pretty proud of this programming project that I came across in this book I'm working through. I only really had problems on figuring out the formula for detecting whether the two ...
8
votes
1answer
144 views
Finding largest subset of line segments that don't intersect
I completed a challenge of codeeval called BayBridges. It can be found here. I have uploaded my code on GitHub here.
In summary, the challenge is to take a list of line segments, each specified by ...
7
votes
2answers
138 views
Performance Issues: Finding 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 ...
3
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1answer
301 views
Calculating the distance between one point, and many others
In my program, I have entities that I call "blobs", because they have a blobby shape. Blobs are polygons. If I have two blobs, then their information array would look like:
...
11
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5answers
471 views
Checking if a list of coordinates defines a closed, exact rectangle
I have to determine if an N sized list of coordinates defines a closed, exact rectangle.
I start with the question "How do I check if a list of coordinates is in the shape of a rectangle?"
The ...
3
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2answers
216 views
Calculating if a point is within a polygon, or outside of it
Here is the function (along with its support functions):
...
5
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1answer
263 views
Calculating “element-wise” the angles between two lists of vectors
Let's say you have two lists of vectors:
v1s = [a, b, c]
v2s = [d, e, f]
I am interested in generating the following ...
14
votes
2answers
500 views
Calculate the intersection between two intervals on the same circle
I want to calculate the ratio of intersection between two intervals; the length of the intersection divided by the length of the shorter interval.
If two intervals do not intersect, the ratio is 0. ...
4
votes
1answer
424 views
Quick Hull Algorithm implementation for higher dimensions
I tried to implement the Quick Hull Algorithm for computing the convex hull of a finite set of D-dimensional points. Here is the repository. Algorithm itself:
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3
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1answer
129 views
Point in a polygon algorithm
I am implementing a Point in polygon algorithm.
Inputs:
M, N: size of the matrix
poly: a ...
7
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1answer
141 views
3D vector CUDA kernel
I designed this CUDA kernel to compute a function on a 3D domain:
p and Ap are 3D vectors that are actually implemented as a ...
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1answer
60 views
Find triangles from line
I have some lines that form triangles. I'd like to challenge the fastest way to find all triangles.
In particular the code should take an ArrayList of Line2D object and return an ArrayList of ...
5
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2answers
578 views
Python implementation of the Ramer-Douglas-Peucker Algorithm
I recently implemented the RDP polygon approximation algorithm in Python and I'm skeptical of whether or not I implemented it correctly of with the greatest efficiency. The algorithm runs in around ...
5
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2answers
626 views
Class Vector with Python 3
Here is a class vector in python 3, for n-dimmensional vectors. Please suggest ways to improve the code as well as fix bugs and errors.
The only rule is not using: numpy, sympy, scipy and so on. Only ...
5
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0answers
152 views
Ways of speeding up this python implementation of SAT (Separating axis theorem)
A project I was working on required the usage of the Separating Axis Theorem to detect collisions between two convex polygons in real time. So I implemented a basic class (...
4
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1answer
343 views
Optimize vector rotation
I have a trivial function that rotates 2d vectors, and a method in a class representing a polygon that rotates every point in the polygon around an origin. The code is fairly optimized as it is, but I ...
3
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3answers
825 views
Algorithm to get an arbitrary perpendicular vector
Is there a more efficient/direct way to find an arbitrary perpendicular vector of another vector?
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9
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1answer
680 views
Faster computation of barycentric coordinates for many points
I'm just starting to understand the Python syntax and I created a module that does what I wanted, but really slow.
Here are the stats of cProfile, top 10 ordered by ...
7
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2answers
232 views
Calculating angle in isometric view
I have an angle where I need to convert a 'normal' angle to an isometric angle (116 degrees), and I came up with this function. It works, but I was wondering if the math could be optimized/simplified, ...
2
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1answer
49 views
How to reduce execution time for this clustering computation?
Is there any way to reduce total execution time for the function getSilhouetteIndex? P.S. I am using weka SimpleKMeans for ...
4
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2answers
119 views
Centroid of a polygon in Clojure
I am studying Clojure and functional programming. I wrote this function to compute the centroid of a polygon specified as a vector of points, e.g. ...
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1answer
183 views
Computing tangent space basis vectors for an arbitrary mesh
This is more like a share and a request than a question. I converted Eric Lengyel's code, which calculates tangents of a mesh for the purpose of texturing and normal mapping, to support SIMD. For this ...
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4answers
224 views
Refactor code to find four co-linear points
I am relatively new to Java, but have been reading up on how to improve the quality of my code.
I am writing a system where I take in a series of points from a file with x and y co-ordinates and by ...
2
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2answers
136 views
Move Line across Plane
I want move a Vertical line segment across a plane or another way sweep the plane, from Left to right.
The figure illustrates how the segment is moving at the X-axis. When x1 >= X beginning and i ...
8
votes
1answer
1k views
Best way to work out angle between points?
I have the following JavaScript code to work out the angle between two points (clockwise). The code I have seems a bit "hacky" to me, as I have a while loop ensuring the number is not negative (to ...
5
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1answer
185 views
Complex logic that I'm certain can be simplified
This is code from a grappling hook implementation. This is specifically code that, after a block is detected between two way points, it tries to find a path around.
This particular piece of the ...
15
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3answers
4k 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 ...
7
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2answers
459 views
Graham Scan convex hull algorithm
I'm beginning to learn Haskell. I've implemented the Graham Scan algorithm for detection of convex hull following the Real World Haskell book.
I'm looking for general advice regarding the style and ...
7
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3answers
326 views
Optimizing a loop in C for a microcontroller
I am trying to draw a Checkerboard pattern on a LCD using a GUI library called emWin. I have actually managed to draw it using the following code. But having this many loops in the program body for a ...
2
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1answer
253 views
recursive algorithm to obtain grid points inside a n-cube volume or surface
I did wrote in python two functions to return points in the n-dimensional cube of half size K (meaning that the coordinates along each axis go from -K,.. 0.. K). The n-dimensional cube volume should ...
14
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2answers
812 views
Speed up solution to Project Euler problem 75
I've been programming for a few months now, and have used Stack Overflow a great deal, but this is my first post. Anyway, I wrote this code for Project Euler problem 75, which asks how many integers ≤ ...
2
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1answer
385 views
Creating shapes program with multiple classes (different files)
I just started to learn Objective C with Programming in Objective C by Stephen G. Kochanand and I would love to get your feedback to see if I'm getting OOP concept with Objective-C right.
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1answer
58 views
Optimizing mathematical index calculation function
I have made a function which calculates the index of a point to which an arbitrary point on a polygon made of XY points belong.
This is a visual representation:
And this is the function I made:
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