Divide curve from midpoint out

What's the most efficient way to divide a curve by length from the midpoint out? And to make it even more fun, how would I do the same but with the segments centered?

Context: I'd like to write a definition to create panelized railings (think glass railings) along a curve. Panels are best manufactured at equal lengths, so I'd array a 1m panel, then have whatever is left over be a unique panel. There are many conditions that I might want to try:

1. Standard size from start, left-over size at end.

2. Standard size from end, left-over size at start.

3. Edge of standard size from midpoint, equal left-over size at start and end.

4. Center of standard size from midpoint, equal left-over size at start and end.

I'd like to switch between these 4 cases along with adjusting the length of the standard size panel to find the best solution.

So I could also ask if anybody knows of a preexisting solution that's already out there, too.

Any help would be greatly appreciated.

Replies to This Discussion

Permalink Reply by Vicente Soler on April 17, 2014 at 7:08am

Given a list of lines representing the balausters:

- The control points component creates a new branch for each containing the start and end points.

- The logic of the path mapper is to place the start points of the odd balausters and the end points of the even balausters in one branch and viceversa.

To solve this xnor gate or logical equality I just use integer numbers and check if they are equal (B%2 will return 0 on even paths and 1 on odd paths. The start points on each branch have an index value of 0 and the end points of 1).

Permalink Reply by Danny Boyes on April 17, 2014 at 3:34am

A further development of the same concept to achieve #4

Except this time you remove the first half section of each curve before [Dividing by Distance]

Permalink Reply by Ángel Linares on April 17, 2014 at 5:40am

I think that #4 has no easy solution for twisty curves...indeed not only the left-over piece will vary with a geometric and only-standard-components approach, but the number of panels at each side of the mid point. Indeed, mid-point on the curve (talking about length) shouldn't be that point.

Permalink Reply by Vicente Soler on April 17, 2014 at 5:47am

Are you implying that #3 has a direct solution without having to use an iterative approach like Kangaroo?

Permalink Reply by Ángel Linares on April 17, 2014 at 9:02am

Nope, I don't :P, consider my comment enclosed in [#3 OR #4] domain. Today we have 30ºC over here (Sevilla)...perhaps the fast temperature change has some bad consequences in the post writing process :P

Permalink Reply by Vicente Soler on April 17, 2014 at 9:58am

We're not too far behind in Madrid, 29ºC right now.

You are closer to the sea, that regulates temperature. Here we don't have spring, we go directly from winter to summer.

Permalink Reply by Danny Boyes on April 17, 2014 at 10:06am

Where as we just get winter :)

Permalink Reply by Vicente Soler on April 17, 2014 at 10:15am

But you pay almost no taxes. The grass is always greener... (in this case it really is)

Permalink Reply by Danny Boyes on April 17, 2014 at 10:23am

The grass is green and the tax is low...

... when winter comes there is no snow.

It should be the new advertising campaign :)

Permalink Reply by Damon on April 17, 2014 at 1:51pm

Well, this has been a productive conversation for me, at least. I'm not all that concerned about a completely general case. Personally, I'm dealing with fairly simple cases (the example earlier of a curve that turns back on itself is unlikely for me) of lines, arcs, and partial ellipses.

Therefore, Danny Boyes's solution of splitting the curve at the center and working out with either the full-size or half-size should be good enough. I'm not going for fabrication, just schematic design.

Thank you all for the discussion. I'll take what I've learned, implement it, and post what I come up with if anybody is interested. Next up, using the HUMAN plugin to use blocks so I can model custom balusters and panels!

Permalink Reply by Vicente Soler on April 17, 2014 at 2:03pm

What is the advantage or not using my file?

Permalink Reply by Damon on April 17, 2014 at 2:14pm

I'm not using your file because you use Kangaroo. I try to avoid solutions with too many plugins. It makes it easier to collaborate. Currently in my office, a lot of people use a few plugins: Geometry Gym and Chameleon to work between Rhino and Revit, DIVA for solar analysis, and Human to interact with Rhino layers, attributes, baking, etc. That's pretty much it. We all have other plugins installed, but we try to limit which ones we use. Given a solution with only native Grasshopper components, even if it's a little less efficient, that's usually how we go.