How to sort points around an ellipse (part 2)

grasshopper

(Claire) #1

Thank you so much to those of you who helped me with my first instance of point sorting, and I’m so sorry for bothering you all again.

My problem this time is this: having generated a vertical “tower” of ellipses that have a different height that I want to wrap my columns around, how do I “stick” my generated points to the ellipses? Right now I’m using the “curve closest point” method, but the problem is that the points curve THROUGH the ellipse, so some of them stick to one half and some to the other, and the resulting polyline is all broken up.

This is the definition I’m using… Basically as you can see, I’ve got the branches of points (each branch of points should connect into one column) as my geometry, which I then move using some equation to generate values. I have a negative and a positive value for each point, so in theory each branch should turn into two columns, one going clockwise and one going anticlockwise. I then take the moved points and find the closest point on the curve. I’ve also tried Pull to Curve.

The problem is, the moved points intersect with the ellipses, so when they get pulled to the curve, the lines end up broken, like so:

The red crosses are the original “moved” points, and the green crosses are the closest points on the curve.

The issue is that limiting the ellipse to say 1/4 of the curve is not very helpful, because ideally I want the column to be able to wrap around the edge (past the 1/4 mark) of the ellipse, like so:

It doesn’t have to be a very steep curve, but it should still be able to wrap the building, and the degree to which it wraps should be something that I can change easily.

This image was done by generating the point co-ordinates on an excel spreadsheet, but of course it’s not as mobile as it would be if I could do it in grasshopper. Any ideas?? I’m seriously stuck.

ellipse building v4.gh (47.4 KB)


(Pfotiad0) #2

The blitzkrieg answer is that there’s no definition around thus what to test? thin air? (BTW: what you are asking is rather easy).

Moral: post the thing (unless that tower is the new NSA headquarters) plus a Rhino file for any referenced data (if any).


(Matt Gaydon) #3

Here’s a quick code to get you started. If you need the columns to follow a given pitch and not change depending on floor heights that’s possible too, but requires a slightly different workflow.

Ellipse Tower - Spiral Columns.gh (14.5 KB)


(Matt Gaydon) #4

##UPDATE## USE ME

This Code now gives you a uniform column pitch independent of floor heights so a much smoother transition with no kinks, if you where to put a double height eg. Mech Floor/ sky lobby etc.

Also it gives you the option to set the location of the column bases in plan using defined points. I am still working how how to control the column pitch with an angle and not just by visually.

It take the top bottom Ellipse Creates a mid one then uses the same logic as the first code to create the spiral curves, though these are then used as rails to create surfaces to intersect with the floor curves. giving you the points on the floors to draw the column lines though.

Note: Code contains both options, though i would advise using the Column Pitch Uniform option.

Ellipse Tower - Spiral Columns.gh (21.0 KB)