Radial Sorting?

How might I sort random points in a plane by their angle from the plane's U vector in a clockwise (or counter clockwise) direction?

Or more precisely, sorting the angle between the vectors created by each of these random points from the plane's origin and the U vector.

Replies to This Discussion

Permalink Reply by David Rutten on March 4, 2011 at 11:57am

You need to compute the vector angle between the plane X-axis and the plane origin -> point vector. Furthermore you need to compute this angle in 2D, as that's the only way you'll get a full circle angle (in 3D, only half circle angles are possible).

Then you can sort the angles while sorting the point in parallel. See attached.

David Rutten

david@mcneel.com

Poprad, Slovakia

Attachments:

SortByAngle.ghx, 126 KB

Permalink Reply by Gabe Krause on March 4, 2011 at 3:22pm

That is exactly what I did, expecting that the Vector Angle component would product a full circle angle given a plane. I must have fed the wrong string because all I was getting were half circle angles.

Thanks for bringing me back to that component. It performs well if it's fed well.

Permalink Reply by Danny Boyes on March 4, 2011 at 1:12pm

Also have a look at this method: http://www.grasshopper3d.com/forum/topics/perimeter-sort

You could also put a circle on the centroid of the bounding box and use that as the boundary curve for the linked method.

Permalink Reply by Gabe Krause on March 4, 2011 at 3:38pm

I really like using the Vector Angle component as it was intended. But after my hooking it up wrong and not realizing it, I came up with this nice alternate for the mean time: