# Convex Hull without the in-built function.

6 views (last 30 days)
Dimitar Dimitrov on 7 Dec 2021
Answered: Jan on 7 Dec 2021
Hello, I want to do the convex hull algorithm without using the built-in function. I know i have to use atan2 fucntion and sort function and that I have to start from the poin with the lowest y-value. But other than that I don't have concrete plan as how to do it. Can anyone guide me?Also,

Bjorn Gustavsson on 7 Dec 2021
Take it step by step.
1, put points on paper.
2, work out how to step from the point with the smallest y-value to the next point along the perimeter in the counter-clock direction, what comparisons and conditions you need to make when selecting the next point, think this out graphically and write down the steps in pseudo-code on another paper.
3, progress to that next point and do the same for selecting the third point.
4, from this you should be able to work out a loop for this.
HTH

Jan on 7 Dec 2021
There are many known algorithms, which can inspire you. See https://en.wikipedia.org/wiki/Convex_hull_algorithms