Creating Holes in a Surface with Various Circles

Hi! ive been working on a project for the past couple hours and i cant seem to figure out how i am supposed to cut holes into my surface. I originally created a lofted surface in rhino and then referenced it in grasshopper and then designed a series of differentiating holes on the surface in order to make it look like the surface has many different kinds of windows within it. I originally thought extruding the circles and then using solid trim would work but i cant seem to actually get them to cut. right now i just have cylinders coming outwards.

im new to the program and ive tried to do my best in terms of teaching myself how the components work because my professors dont really teach us anything, nor do they explain the components. im just having a hard time with this project and im stressing. any help is appreciated.

Hi Vivien

please attach your file. It helps us to help you.

From what I understand in your description, I would assume that you need to ‘cap’ the extrusions to make sure they are all oriented in the right direction before calculating the boolean difference.

(Every surface has a positive and a negative direction which indicates, what part of the boolean difference should be cut and which kept.)

But that’s all just assumptions, please attach your file.

hey ben, i attached screenshots i thought they were visible, sorry.

Final Assignment 180.3dm (6.9 MB)

Final Assignment (175.5 KB)

hopefully these attachments work

thanks for the file.

  1. little attention error: you don’t create a volume, but a frame here:

it should look something like this to have the front and back wall as well for your volume:

  1. for a boolean difference (or any boolean operation) you need the volumes to intersect, which is not the case in your file:

to solve this, move the cylinders into the wall like so (not very elegant, though):

  1. Although it’s probably worth the same, I changed the extrusion of the surface to extrusion of curve and capped them. I feel it’s more safe to avoid closed, negative volumes (which can exist inside grasshopper contrary to rhino)

here’s the file with proposed corrections which seems to work fine:
Final Assignment (51.4 KB)

hope this helps and (as you have lazy professors :wink: ), feel free to ask questions, if there’s something you’d like to have explained more in detail.


wow, thank you so much ben that definitely does help!

so by capping them did the cylinders go through? or was it the fact that you changed the extrusion of the surface to extrusion of curve that made that difference? sorry i am just trying to understand as much as i can for the future.

now with the new placement of the cylinders which components would i use to generate holes in them to make my windows? its the main goal/vision i have for this assignment, i think it will look nice with the different circles all together. how would i go about doing so with these changes?

  • vivien

neither. don’t mix point 2 and 3 together. It’s separate problems.
capping is a function that closes volumes at planar open edges.
If you extrude a surface, you basically already have the volume closed.
If you extrude a curve, the extrusion is still open. with cap you close them.
you can leave this aside, as it’s not important at this point and only leads to confusion. Your solution worked fine for 99.99% of all cases.

here’s where you need to focus:
I made them enter into the wall by moving them half the way back of the extrusion, but in reversed direction like described in point 2. I took the vector you made for the extrusion, reversed it and set the length (amplitude) to half the amplitude of the extrusion vector. if you look at the preview in rhino and the new position, you’ll see what I mean:

No changes needed in your file to obtain this. You already did good for this one.
did you see that I attached the file with the corrections and the holes already cut in the last post?

i see, thank you so much, all this information is beyond helpful, i appreciate it more than you know. how long have you been using rhino/grasshopper?

i didnt even realize the holes were cut too, no sorry, but thank you. how can i preview it the same way you did in the screenshot? when i look over to my rhino file it doesnt show the holes the same way yours does in the screenshot.

oh, don’t feel bad, you cannot compare because I’m old:) since V4, I think 2007. You have the advantage to have a young brain which learns quickly. I’m sure you’ll master grasshopper in no time. Just so you know, your file is very good, it was just a little detail that was off.

try and select all the elements except for the last one, that are light gray and rightclick in the canvas and switch preview on or off. I seem unable to make a screenshot from that though.

thats so cool, interesting too!

and okk, thank you again for all your help:)

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