# List, horizontal lines

**URL:** <https://discourse.mcneel.com/t/list-horizontal-lines/140888>\
**Category:** Grasshopper\
**Tags:** curve, rhino6, surface, lines, polylines\
**Created:** [April 9, 2022, 11:57am UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888 "2022-04-09T11:57:01Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![ashcoaster3](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ashcoaster3/32/362778_2.png) [@ashcoaster3](https://discourse.mcneel.com/u/ashcoaster3)\
**Post date:** [April 9, 2022, 11:57am UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/1 "2022-04-09T11:57:01Z")

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For my support design, is there any way to connect the pieces horizontally like shown in this roller coaster example? So one horizontal connection every other support, so not every support needs a connection to one another. I have tried using list and domain methods but I cant seem to get it to work.

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/6/5/7/6572abc7a1ae982453129b3f25d3348d5f4a3400.jpeg)  
 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/2/1/b/21b7f8e11b2211d4c9df7811cb312c02cbf01468.png)  
[rollercoasterfirstgo (1).gh](https://discourse.mcneel.com/uploads/short-url/a8g2WydOmEa6MJYma5TrPEN5mib.gh) (36.4 KB)

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**Author:** ![maje90](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/maje90/32/762888_2.png) [@maje90](https://discourse.mcneel.com/u/maje90)\
**Post date:** [April 9, 2022, 2:02pm UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/2 "2022-04-09T14:02:12Z")

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I think you have bigger problems:

 ![2022-04-09 16_01_21-Window](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/0/e/b/0eba9a573679b6844e3a329f3f3d0bb378a54a84.png)

Can you describe more globally what are you trying to do?

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**Author:** ![HS\_Kim](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/hs_kim/32/473975_2.png) [@HS\_Kim](https://discourse.mcneel.com/u/HS_Kim)\
**Post date:** [April 9, 2022, 2:19pm UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/3 "2022-04-09T14:19:43Z")

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![Canvas at 23;16;32](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/d/9/c/d9c59a0ca203fa02a6fc858cab8fc972bbd4fb67.jpeg)  
[rollercoasterfirstgo\_re.gh](https://discourse.mcneel.com/uploads/short-url/55iABuUqHcpCicziaA54hRGLlHq.gh) (23.3 KB)

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**Author:** ![ashcoaster3](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ashcoaster3/32/362778_2.png) [@ashcoaster3](https://discourse.mcneel.com/u/ashcoaster3)\
**Post date:** [April 9, 2022, 9:14pm UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/4 "2022-04-09T21:14:09Z")

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Ah yeah so I intentionally disconnected those, I planned on using them later to assign them to lists (which may or may not have been needed anyway). So I am creating roller coaster support structures, in which I want each of the points along the supports to be horizontal with each other (except for the top square that you can see follows the track) much like in the roller coaster example. So I wanted a horizontal connection at every other point in order to create a square, from that I would create trusses using the lunchbox plugin so that each of the lower supports would be identical, but this of course would vary depending on the height of the roller coaster. My goal is then to use the pipe function to set dimensions for each of the truss components (using basic strut and tie ideas to determine dimensions).

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**Author:** ![ashcoaster3](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ashcoaster3/32/362778_2.png) [@ashcoaster3](https://discourse.mcneel.com/u/ashcoaster3)\
**Post date:** [April 20, 2022, 2:00pm UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/5 "2022-04-20T14:00:57Z")

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Thanks for a fantastic solution to the problem! I wanted to ask (at the point shown below in the image) why the list goes from i to i+2, surely it should be i to i+1 on the next rectangle up? Basically I want to know how the truss bracing list was created. Many thanks once again!

 ![image](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/b/b/d/bbd54e81c41c1920af3aace8a9afdd511fd73feb.jpeg)  
[rollercoasterfirstgo (1).gh](https://discourse.mcneel.com/uploads/short-url/uSLmPEc4i6NyNBCUeXe0TwQD34W.gh) (51.2 KB)

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<div class="post-metadata">

**Author:** ![HS\_Kim](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/hs_kim/32/473975_2.png) [@HS\_Kim](https://discourse.mcneel.com/u/HS_Kim)\
**Post date:** [April 20, 2022, 2:11pm UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/6 "2022-04-20T14:11:06Z")

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> [@ashcoaster3](#):
>
> why the list goes from i to i+2, surely it should be i to i+1 on the next rectangle up? Basically I want to know how the truss bracing list was created.

It seems you totally misunderstand the source of discontinuity points data comes from…

The data comes from the faces output of Deconstruct Brep. If you turn the preview of that component on, you’ll know what I mean.

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**Author:** ![ashcoaster3](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ashcoaster3/32/362778_2.png) [@ashcoaster3](https://discourse.mcneel.com/u/ashcoaster3)\
**Post date:** [April 20, 2022, 2:16pm UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/7 "2022-04-20T14:16:10Z")

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Hi again, so I have had a look at the Deconstruct Brep component but I am not entirely sure what I am looking for within this. I see all the rectangles are connected together with vertical lines. How does this determine the discontinuity points?

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<div class="post-metadata">

**Author:** ![HS\_Kim](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/hs_kim/32/473975_2.png) [@HS\_Kim](https://discourse.mcneel.com/u/HS_Kim)\
**Post date:** [April 20, 2022, 2:33pm UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/8 "2022-04-20T14:33:23Z")

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> [@ashcoaster3](#):
>
> How does this determine the discontinuity points?

 ![Canvas at 23;32;47](https://global.discourse-cdn.com/mcneel/uploads/default/original/4X/d/c/a/dca83ac2bca9c6909ebc5c1129c21b8dddc62fd5.png)

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<div class="post-metadata">

**Author:** ![ashcoaster3](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/ashcoaster3/32/362778_2.png) [@ashcoaster3](https://discourse.mcneel.com/u/ashcoaster3)\
**Post date:** [April 20, 2022, 2:38pm UTC](https://discourse.mcneel.com/t/list-horizontal-lines/140888/9 "2022-04-20T14:38:40Z")

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AHHHH I kept thinking it was to do with the horizontal rectangles, thank you so much!