Sort a list of points clockwise

Hello Everyone,

I'm having trouble figuring out the best way to sort a list of points clockwise. These points are the vertices of a surface.

I've tried sorting the list based on the angles between the lines that join the centroid and the vertices, and a line between the centroid and a reference point, but this does not always work.

I'm basically looking for a C# equivalent of the sortAlongCurve component. Any help would be great!

Thank you!

Replies to This Discussion

Permalink Reply by Daniel González Abalde on February 5, 2016 at 12:31pm

Sort Along Curve component with the boundary as curve guide. Flip that curve guide if neccesary.
This not work?

Permalink Reply by Nidhi Sekhar on February 5, 2016 at 12:45pm

Hi Daniel,

I'm sorry I wasn't more clear. I am trying to create a component in Visual Studio in C# and I'm trying to figure out how to write code that works like the sort along curve component.

Permalink Reply by Daniel González Abalde on February 5, 2016 at 12:53pm

Oh xD

Then I think something like:

t = List of parameters(as double)

For each pt, Closest Point to curve -> t.add(cpt curve parameter)

array.sort(t as keys, points as object)

Permalink Reply by David Rutten on February 5, 2016 at 1:12pm

Sorting along a curve is harder than just sorting by angle. But in both cases you need to use the Array.Sort() overload which takes two arrays, one for the sorting keys and the other for the points.

Point3d[] points = ...;

double[] angles = new double[points.Length];

for (int i = 0; i < points.Length; i++)

angles[i] = Math.Atan2(points[i].Y, points[i].X);

Array.Sort(angles, points);

Edit... Daniel beat me to it.

Permalink Reply by Nidhi Sekhar on February 5, 2016 at 2:20pm

Thanks David, Daniel. That worked!

Permalink Reply by peter fotiadis on February 6, 2016 at 12:01am