Region Union won't connect curves to become 1 closed curve

Hi. First of all; I’m new to grasshopper, but really eager to learn more! I figured that instead of sitting and watching tutorial after tutorial, I’d much rather just start off by attempting to create something that I want and then face the challenges as they appear. So far it has worked out perfectly, but I just hit the wall! And after lots of frustration and Googling, I’ve given up. Oh, I also tried asking ChatGPT for help, but it obviously has no idea about GH!

So what I want to do is create an outer wall and an inner wall of a vase by lofting curves. I then want to cap both breps and do a solid difference to make the final design. I initially thought I had an issue with the “Cap Holes” component as I somehow got the curves to loft perfectly after fiddling with graft/flatten/simplify/reverse but Cap Holes would say that it failed to return a result. Upon further investigation, it seems that my Region Union is not able to connect the curves to become 1 closed curve. Could this be the reason for my struggles? What should I do to fix it?

Any help is deeply appreciated! Have a wonderful weekend!

Region Union problem.gh (14.1 KB)

Region Union_2023Feb3a.gh (17.6 KB)

The overlap of the small rectangles with the circles was sketchy so I added a ‘nudge’ slider (yellow group) to compensate. Made other changes to how the inside and outside of the container are joined to form a ‘Closed Brep’ (I thought it was but now it’s not?). Created the bottom separately.

P.S. Sorry, I thought I had it but obviously not. I’ve tried all the tricks I can think of. :cry: :thinking:

1 Like

OK, I finally got it. There is always another way…

I gave up on lofting the region unions approach and created a “solid” (‘Closed Brep’) from the outer and inner circles, then used SUnion to add the ribs. Finally used SDiff to create the bottom and SUnion to join it to the ribbed walls. The very last thing was one missing rib due to being on the loft seam so rotated all the ribs 45 degrees to fix that. Whew! :sweat:


Region Union_2023Feb3b.gh (24.9 KB)

1 Like

Thank you, Joseph! I see you’ve done quite a few things differently than I did. Now I get to learn what each component does so that I can become better! Thank you very much!

When I open up your file, I have an error in the “nudge”-group where it seems like no data is coming out from the Offset Component:

That’s very odd, it works for me. Did you change anything? What is your Rhino tolerance value? You can see it using ‘View | Display Options… | Units’ in Rhino. Mine is 0.001.

P.S. By changing my tolerance value, I can get the model to fail but not the same way. Maybe try increasing the offset slider value?

1 Like

Nope, I changed nothing. My units appear to be the same as yours:

By increasing the offset slider value, nothing else happens. I see that the wires connecting from the output of the offset to the other components are red. What does that mean? They are usually black or dotted. I really appreciate you trying to help me! Thank you so much!

For what it’s worth, I got the region union solution to work.

  • Grafted everything from the start, your tree structure was definitely wrong in the Region Union component.
  • Centered and extended the rectangles inside the circles
  • Exploded and re-joined the Loft for it to become closeable with Cap Holes
  • Not sure about the bottom part being what you want but the end result is a closed Brep.

Region Union problem.gh (12.6 KB)

1 Like

I don’t get it. Here is the same code replacing Offset with Circle

Region Union_2023Feb4a
Region Union_2023Feb4a.gh (24.6 KB)

1 Like

That one works! Thank you so much!

You are missing the inner wall, eh?

1 Like

So Offset Curve failed for some reason… :thinking: Are you on a Mac? Mysterious.

1 Like

Indeed.

Region Union problem.gh (15.1 KB)

(as a side note, both your files work on my laptop, with default tolerances.)

2 Likes

Thank you both for your amazing help! Now I have the pleasure of learning exactly what each component does for the model and learn it for the next time.

I am on Windows 11. Have a lovely weekend! :slight_smile:

Wow. What about my version ‘a’ from yesterday? The amount of time I spent on this was ABSURD!

Maybe this is a clue? Why does Cap Holes fail from Loft then works from Brep Join? Negative volume perhaps?

cap_holes

Aha! Maybe a GH bug then in Offset Curve on Win 11? @wim ?

It produces the same error I had before blindly trying the Deconstruct/Join trick : there is a nasty naked edge along the vase. This makes the Cap Holes fail, and even if the caps are produced manually as you did, the final join is still open.

I’m still unsure about the design intent for the bottom part of this vase :crazy_face:

1 Like

Thanks. I saw that nasty edge issue but didn’t realize it was a naked edge. Bizarre! I would never have thought of “the Deconstruct/Join trick”. Another GH bug?

I was also puzzled by the sketchy overlap of rectangles and circles that motivated my use of the nudge code I added, which isn’t an issue in your code. But I just figured that out - you constructed a domain that made the rectangles twice as long, which solves the sketchy overlap issue. DETAILS!