SplitBrep? and delete one of the remaining surfaces

Hello!! :)

I'm now starting to learn Grasshopper and already encounter my first problems.

I am trying to split this Brep? with a plane and everything seems to work ok. Now as a next step I want to delete the upper part of the Brep and I dont know how. I will atach a screen shot with my approach, a screenshot with my goal and the GS + Rihno files.

Thank you very much

Attachments:

my approach.jpg, 255 KB
goal.jpg, 29 KB
coloana.gh, 13 KB

Replies to This Discussion

Permalink Reply by Joseph Oster on November 3, 2017 at 7:49am

everything seems to work ok

What makes you say that? I don't see anything working OK at all. You didn't internalize the 'Pt' param, but even if you did, the 'Extrude' results don't make a lot of sense and don't intersect the box you are using as the 'Trim T (Cutter)' input. Oh... Just looked at your images and see that the point is far above the trim box.

But do you realize what the lofted shapes look like? There are many errors in your model...

Attachments:

coloana_2017Nov3a.gh, 12 KB

Permalink Reply by octavian prostean on November 3, 2017 at 7:58am

Thank you very much. :) Yeah like I said ... I've started using Grasshopper 3-4 days ago. I rly appreciate your feedback.

Permalink Reply by octavian prostean on November 3, 2017 at 8:45am

If I look at your changes you internalized the Pt param and then listed the desired part after trimming it. Yes, I didn't knew how to internalize the Pt param so I drew it manually in Rhino and moved it on the Z - axis and then set it on a Pt param in GH. Anyway the extruded point was intersecting the Trim T Box... at least I think it did.

"But do you realize what the lofted shapes look like? There are many errors in your model..." do you still see errors in my model after the changes you did? what do you mean with realize how the lofted shapes look like?

Pls ignore this reply if you think its too stupid. I'm rly trying to understand your feedback so I can learn something out of it . Thank you very much.

Permalink Reply by Joseph Oster on November 3, 2017 at 9:04am

You extruded all six sides of the 'Box', which results in six separate breps; four of them from the box sides and one each from the top and bottom of the box:

You can do anything you want, of course, but I would suggest you try to work with surfaces instead of solids. You can create solids ("Closed Breps") from surfaces, but you need to know the difference.

Permalink Reply by octavian prostean on November 3, 2017 at 9:21am

ah wow. I understand my error now. Thank you . you're very kind. :)

Permalink Reply by Joseph Oster on November 3, 2017 at 9:20am

Here is a cleaner result, obtained by extruding only the top surface of the six faces of the box (though I must say, this is the first time I've ever noticed the 'Extrude To Point' variant):

Attachments:

coloana_2017Nov3b.gh, 16 KB

Permalink Reply by octavian prostean on November 3, 2017 at 9:47am

This list item commend is awesome ( and then choose the face via slider ):) I had the right idea in my head but didn't knew how to communicate with GH.

I have one more question. I would like to attach the base ( starting box ) to the extruded part and bake them together. Every time I do it they are baked as 2 separate elements. This worked in the first try because all 6 faces were extruded.

Permalink Reply by Joseph Oster on November 3, 2017 at 10:11am

This worked in the first try because all 6 faces were extruded.

No, it really didn't work. You baked all six results at the same time but they were separate breps, not joined and certainly not "Closed Brep" (solid).

Here's how - 'Shift' list with 'W (Wrap)'=false is used to get all the faces except one, from the original box and from the extruded surface; then 'Join' is used with the 'B' input flattened (otherwise you get two results), and finally 'Cap' ends to close the hole at the top :

Attachments:

coloana_2017Nov3c.gh, 18 KB

Permalink Reply by octavian prostean on November 3, 2017 at 11:34am

uhmm ... yes it didn't :)). Thank you very much for your advice and help. better then my teachers at the university haha

Permalink Reply by Chapulin Colorado on November 3, 2017 at 9:46am

hi,

just a general suggestion, if you just need the lower part i wouldnt do it like this, since boolean operations trim, split,... always are a hassle in rhino and even more in gh.

so if you are just interested in the lower portion you could do it like this: