Anyone knows about how to cull the lines inside a boundary?

[Larkin_Chan]

Hi everyone,
As I am new to Grasshopper, I am not sure how to exclude the lines inside my core wall region. I have tried to use the cull function, but it seems like the lines are following the grid, which has no physical points inside the wall region. May I know whether anyone has any thoughts on it?

Also, I have attached my current script; it looks a bit of a mess, but the beam script is grouped in red colour. I hope it helps to understand my question.

Parametric Model Script_11_02_2_2026.gh (92.9 KB)

[Eef_Weenink]

dear Larkin, would love to help yout. but your file is loaded with plugins. I don’t know them and do not want to install them.
So please isolate the issue by internalising the input into the area and upload that without plugins.
If the plugins are essential to your question, please mention them, so the experts, who also you these, will respond,

regards, Eef

[Larkin_Chan]

Thank you Eef Weenink. The plugins are essential to the script because the beam positioning is based on the grid. The plugins I used are ggETABS (for the structural analysis) and Bullant (member shape).

[Quan_Li]

Help Us Help You - Grasshopper - McNeel Forum

[Eef_Weenink]

OK, then please change the categories of this (your) thread in the forum, so people know.
+
I agree with @Quan_Li → Your .gh look likes spaghetti going al over the place.
Best is to isolate the region where your problem lays and you are working.
Group components in functions and some labels to the groups will surely help.

Regards, Eef

[ftzuk]

Then internalize the relevant data. If your question is about culling lines inside a boundary - then just provide the lines and the boundary.

[Larkin_Chan]

Thanks, everyone, for the advice. I will attach where the main problem is, with another script provided below.

Question on beam positioning_05_2_2026.gh (46.3 KB)

The image below, shows where i would like to erase (the red lines inside the orange square)

Thank you for your reply, Ftzuk. I have been trying to cull the lines inside the boundary, but it seems not to be working. Did I do something wrong when forming the polyline?

If the script is still unclear, please tell me what particular part I can isolate.

[Larkin_Chan]

The part here is about the grid system, so the main problem is where the far right-hand side has a red group box, and is named beam positioning.

[ftzuk]

Can’t even see a grid when I open your file.

[Larkin_Chan]

As I mentioned, the grid system is using the plugin, ggETABS, so that’s why there is nothing showing in your version.

[ftzuk]

Internalise the output from that plugin.

[Larkin_Chan]

Question on beam positioning_05_2_2026.gh (34.7 KB)

Thank you, Ftzuk. I internalised the grid system, so it should be clear to you now, and now you will know where the lines are.

[diff-arch]

Hi,

Your grid-like structure is currently represented by rows/columns of points in a data tree.
Each tree branch represents one row or column, depending how you look at it.

Downstream this leads to a confusion, when you cull the points inside the extrude region.
The culling works fine, as shown for the highlighted row/column of points below.

However, when you later construct polylines out of the rows/columns of points, they are created for all the remaining row/column points. Since these are in successive order in each row/column in tree branches together, it bridges the desired gap with a line segment.

As you can see the resulting polyline has no vertices in the extruded region, but a spanning line segment.

To remedy this, I would simply construct the polylines beforehand and cull each ones segments, whose middle points lie in the extruded region.

Note, how I had to sanitize your grid data at the beginning. I wouldn’t pollute one data chunk, here the grid points, by introducing different data.

In most cases, keeping everything separate makes it much easier to work with!

Answer about beam positioning_06_2_2026.gh (32.6 KB)

Furthermore, you seam to run an older version of Grasshopper (0.7?). I saved the file in the latest version (0.8), so fingers crossed that nothing broke.