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Full Version: boolean diff wtf

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From: Mr. Yuri (MR_JURAJ)
10 Mar 2019   [#1]
Hi,
I'm trying to subtract small objects from big object but once I do that there are no sides created where objects were touching.
So model will become open as walls are missing.
I think it's very simple boolean diff operation but for some reason SW just don't behave like one would expect.

It's things like these that makes me sometimes curse at night.
I design something for hours and then spend 90 minutes trying to figure out why MOI doesn't do simple thing properly.

Can anyone explain to me what is the deal with this?
Thanks a lot.

Attachments:
tshoot.3dm

Image Attachments:
walls missing.PNG 


From: Michael Gibson
10 Mar 2019   [#2] In reply to [#1]
Hi Mr. Yuri, the problem there is your main object is not a closed solid volume, if you select it you can see the object type indicator says it's a "Joined srf". It would read "Solid" there if it was a closed solid:



For booleans to do their normal operation the objects involved must be closed solids so that pieces to discard can be identified by which volume they are contained within.

If you do a boolean on an object that is not a closed solid volume it will behave more like a surface trimming operation.

To find out what areas of your object are not closed and preventing it from being a solid, set up the script described here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2

- Michael

Image Attachments:
Juraj_not_solid.jpg 


From: Phiro
10 Mar 2019   [#3] In reply to [#1]
Hi,

Your "big object" isn't a solid.
So, boolean difference can't give you a solid.

If you don't want to build a big object as solid before Diff, you have to construct the face after the Diff, then "join" new faces to your joined suf (big object).
From: Phiro
10 Mar 2019   [#4] In reply to [#3]
Michael is 1 minute faster than me to give the soluce... Sorry.
From: moujiik
10 Mar 2019   [#5]
Hi Mr Yuri. Your object is not a solid. It's says: joined surfaces. And there are a lot of holes in jour model. You need to repair your model to make it a solid. Then you can make a booleann diff whith your two other solid.

edit:to late

Attachments:
tshoot solid.3dm


From: Frenchy Pilou (PILOU)
10 Mar 2019   [#6]
dispit of that all works fine without making solid! ;)
Just increase size of little objects! (Scale 1 D)
Make the Boolean Diff even all the big object is not a solid. That works!
(but sure your big object wiil be not always transformed in solid! :)

From: Michael Gibson
10 Mar 2019   [#7] In reply to [#6]
Hi Pilou, if you zoom in and look carefully at your case with just making larger cutting objects you should see that there is still a problem there that there are open areas because the pieces of the cutting objects will not be left behind.

Pieces of the cutting objects will only be left behind when doing a boolean on a solid object, not on an open surface object.

- Michael
From: Frenchy Pilou (PILOU)
10 Mar 2019   [#8] In reply to [#7]
yes of course because big object was not a solid...

But than can help to imagine what will be the object to make some differences for go away and at the end close the faces to make a real solid...
maybe more easy to make a solid with the result simplyfied than try to make solid at start ?

Don't know if it's a true walk around! :)
From: Mr. Yuri (MR_JURAJ)
10 Mar 2019   [#9]
Ok. Thanks for pointing out solid thing while booleaning.
I tried inline script by selecting object > TAB > var gd = moi.geometryDatabase; gd.deselectAll(); var breps = gd.getObjects().getBreps(); for ( var i = 0; i < breps.length; ++i ) breps.item(i).getNakedEdges().setProperty( 'selected', true );> Enter > and nothing happened

Had to assign shortcut (also in latest V4).

But now it highlighted edges and have no idea how to close them effectively?
It's weird shapes inside object that I have no idea how happened as I was only booleing solids as far as I know.

Thanks
From: nameless
10 Mar 2019   [#10]
Hi Yuri,

I think the move that created the joined surface, was the boolean subs very close to the front end of the "boat". I went ahead and redid them carefully and I got a solid. The weird connection at the cylindrical part at the front is because I tried to retain as much of your original model as possible (I copied your own surfaces there).

If you try to boolean subtract the two solids at the back now, I think you get the expected result.

Attachments:
tshoot_z.3dm


From: Mr. Yuri (MR_JURAJ)
10 Mar 2019   [#11] In reply to [#10]
Thanks nemeless,
Is there a way of you showing me how that can be made other than some painstaking 20minute method? :)
Or point me to some resource where such things are explained.

Downside of MOI is that there is no training dedicated to explaining step by step countless functions that MOI have.

It's amazing what can be modeled there but workflow is "weird" for beginner non-programmer and adjusting models afterwards is such process that sometimes I want to end my life.
Especially with such models as I pasted where curves and planes are not on 2D.

Thanks again for you help.
From: nameless
10 Mar 2019   [#12] In reply to [#11]
Hi Yuri,

I totally get it. My recommendations:

1)Read the actual manual of the program, command by command: http://moi3d.com/3.0/docs/moi_help.pdf
I know it seems tedious and we are all used to things being chewed for us, but it's by far the best way to understand the tool.

2) Chipp Walters vids on youtube were a great help for me.

3) (and probably most important) Keep modelling stuff in MoI and create your own shortcuts for the tools you use most. With time, you will start working around problems and develop strategies to approach shapes. You will start to expect what could be an issue and start to enjoy the process. By getting familiar with construction lines, the edit frame and snap modes you will get a very undisturbed and intuitive flow, almost like sketching.
From: Michael Gibson
10 Mar 2019   [#13] In reply to [#11]
Hi Mr. Yuri, the type of model you're working on with some internal structures not really visible from the outside is not very typical. Being not very typical means that it's not too likely that you will find a tutorial that would cover exactly what you are trying to do here.

Model structures like that I'd say are inherently more difficult to work with, so I'm not surprised that you get frustrated. It's not great to work on an unusual and fundamentally difficult type of model as a beginner. It's better to work on simpler models as a beginner and work on more difficult styles when you have more experience.

But it can accelerate your learning curve to work on more difficult cases though too, as long as it doesn't cause you to give up rather than gain experience of course.

I'm examining your model now to see if I can repair it, the repair job is going to be fairly complex. For a start I think I figured out there is a missing piece here which reduces the naked edge count from 20 to 18:



- Michael

Image Attachments:
yuri_first_piece.jpg 


From: Michael Gibson
11 Mar 2019   [#14] In reply to [#1]
Hi Mr. Yuri, I have attached a repaired version of your object that is now a solid and should now behave as expected with the boolean difference you wanted to do.

I needed to build 3 planar surfaces and one extrusion, and then use Edit > Join to glue those into place to eliminate the holes that were surrounded by naked edges which you saw highlighted when using that script.

- Michael

Attachments:
tshoot_repaired_3dm.zip


From: Mr. Yuri (MR_JURAJ)
12 Mar 2019   [#15] In reply to [#12]
Hi nameless,
I read the manual (trying to comply with RTFM policies) but there is so much info I'm not able to memorize all and I actualy have it in pdf handy but when I get a problem and search, maybe I'm using wrong keywords.

Watched Chipp Walters vids and basically all I could find but rarely they try to solve exact problem I encounter. And as I'm not profi 3d artist and programmer I don't sometimes put 2+2 together like other folks here using MOI.

I do model but it's not my profession and when I model I rarely need very simple part. I was using Designspark mechanical for long time but as I need more complex parts I did research and found MOI. Now even when there is something I could do in 5 minutes in DSM I do it in MOI as I want to learn. Many cases I crash on moi bugs, downsides or my inability to realize thing like above case.

As DSM was more intuitive (for me) it's not that easy to use MOI with same ease.
I know it is more powerful but I have to change almost everything I'm used to in creating models.

I appreciate your help.
From: Frenchy Pilou (PILOU)
12 Mar 2019   [#16] In reply to [#15]
Using Shortkey is really when you want win some micro-times in very repetitive actions on some numerous objects!

It's not pleasant to use icons ? You know exactly that you make quietly...with maximum of efficacity!

You have all specifics addon pluggins on a special icone menu...and an icon is more visually memorizable than an abstract Ctrl + Shift + Z :)

With this menu I have 150 functions under hands with confort!

I use only K for subdivide, P for SSplit, B for Bridge, L for Loop selection, R for Rebuild :)
I can't memorized more!


From: Mr. Yuri (MR_JURAJ)
12 Mar 2019   [#17] In reply to [#16]
Looks awesome.
Can you please share how can I add this to MOI?

Thanks
From: Frenchy Pilou (PILOU)
12 Mar 2019   [#18] In reply to [#17]
You have the same for the object! ;) I must refind for the Icon Menu! ;) All was for the V3...I am waiting the V4 for see there is no news functions...
http://moi3d.com/forum/index.php?webtag=MOI&msg=6507.241


From: Frenchy Pilou (PILOU)
12 Mar 2019   [#19]
Refound for the palette of icons Commandes! ;)

http://moi3d.com/forum/index.php?webtag=MOI&msg=7862.1
From: nameless
12 Mar 2019   [#20]
Hi Yuri,

I am an illustrator/2d guy myself, that's why I said I totally get it. :) Trust me that it get's a lot better with persistence. I would not try to memorize the manual per se, just make a pass of each tool testing it on a very simple dummy project.

Pilou, shortcuts are not only to save time, I think. I feel it's a way to protect concentration and flow when one is concepting on such an intuitive tool as MoI. I highly recommend setting up shortcuts after you get some basic understanding, so that you start developing muscle memory to the point that you think "chamfer" and the edge is chamfered before you realize it. :))

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