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Please HELP me with this generate complex fail

9 REPLIES 9
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Message 1 of 10
robert68ZEY
1319 Views, 9 Replies

Please HELP me with this generate complex fail

I need fill regions at these group boundaries in order to split this 'slab' into 3 distinct final parts. I've tried manual and auto-generating. Each time the tool just creates a new GC object but the fill regions are separate objects. I don't get 3 closed objects like I would expect.

What am I doing wrong?

Is there another way to split this object into 3 distinct parts as I've indicated by the painted face groups?

4 screen shots here showing progress (someone please explain how to upload a mm file. I tried 3 times and it wouldn't post until I removed the attachment. It's 7MB, is that too large?). When I hit accept only some of the boundaries highlight bright green, others are blue. Split complex just creates separate surfaces, which I have to manually go back and reconnect to the manually separated object:

original with face groupsoriginal with face groupsaccepted showing resultant complex with only some boundaries with green highlightaccepted showing resultant complex with only some boundaries with green highlightgc in progress with double clicked boundariesgc in progress with double clicked boundariesresult after split complex showing fill regions created but no solid final objectsresult after split complex showing fill regions created but no solid final objects

Thank you for any help! This tool is amazing, I really want it to work for me on this project!!

9 REPLIES 9
Message 2 of 10
MagWeb
in reply to: robert68ZEY

Complex is the only straight way splitting an object non planar . One might consider to create a subtraction object and using BooleanIntersection and BooleanDifference but that's more difficult in most cases.

 

The reason why your object does not work is that the white group "touches" the green group with two separate boundary loops. Towards the brown group exist four such contacts. GenerateComplex is limited to one touch per group pair . Further interior surfaces you do aren't handled properly (not duplicated and not welded). That's why you find only one green line at white to brown and one to white to green in your result.

 

To fix such an issue one similar example. The white group touches the red as well as the blue group three times:

Ohne Titel.jpeg

Select the white group

Ohne Titel 2.jpeg

Separate it hitting Y and hide the blue-red object, double click right at two opposite boundaries to select their boundary faces. With Shift+. (dot) expand this selection several times:

Ohne Titel 3.jpeg

Convert the selection to a face group and do the same on another pair.Ohne Titel 4.jpeg

Show the red-blue object, combine it with this object and run EDIT/CloseCracks to weld:

Ohne Titel 5.jpeg

Now there's one boundary loop RedToCyan, CyanToBlue, RedToYellow, YellowToBlue, RedToPink, PinkToBlue each and GenerateComplex does its job properly. Do it manually by double clicking the loops:

Ohne Titel 6.jpeg

Done:

Ohne Titel 7.jpeg

Do NOT join the pink cyan and yellow group before splitting the complex! Otherwise you run into some flipped faces issue at the yellow and pink interior surfaces.



Gunter Weber
Triangle Artisan

Message 3 of 10
MagWeb
in reply to: MagWeb

Maybe faster:

select the white group and do a selection based PlaneCut (Edit/PlaneCut) in CutType SliceGroups from hole to hole.

This results in this grouping:

Ohne Titel.jpeg

This does the job too



Gunter Weber
Triangle Artisan

Message 4 of 10
robert68ZEY
in reply to: MagWeb

This works great! Thank you.

Message 5 of 10
robert68ZEY
in reply to: MagWeb

I'm not following you on your second idea about plane cut and slice groups...

Message 6 of 10
robert68ZEY
in reply to: MagWeb

Wait a sec, hold the phone. I just noticed the middle shape has flipped faces. 

I followed procedure as you stated. All boundaries turned bright green after GC.

After split, I get the two parts on the sides real nice, but middle part some faces flipped. And its really difficult to select them for some reason. In fact, when I do manage to flip some of them, the face groups are not double clickable. 

Ideas?

gcfaceflipped.PNG

 

 

One fool proof way that seems to work well right now is to just bool the middle from the rest.

Separate out the middle part, autoclose the boundaries, then bool that from a copy of the original.

Message 7 of 10
MagWeb
in reply to: robert68ZEY

There's PlaneCut in EDIT and in SELECT/Edit.

Both variants of the same tool have a CutType: SliceGroups. This doesn't split the mesh but only cuts the groups.

Navigate to a position where you can see empty space in two holes.

Now in SELECT (while the white group is selected totally) it cuts only selected faces and using SliceGroups it only "cuts" the white group into two groups . This gives some small open cracks if you do a selection based cut where the cutting plane intersects the border of selected/non selected. Against this, in your case you can define a cutting plane not intersecting a selected/non selected boundary. Simply define a cutting plane by clicking inside the empty space of hole1 and drag the red line's end to an empty space of hole2. Accepting PlaneCut the selected group is cut into two groups. I need to do this twice in my example above. 

Now Complex finds different neighbour groups and works just fine.

The first workflow above is stable, the second (based on PlaneCut) is faster but might be tricky you might hit non selected surfaces.



Gunter Weber
Triangle Artisan

Message 8 of 10
MagWeb
in reply to: MagWeb

Sorry, crossover posting... just a minute (or more)....



Gunter Weber
Triangle Artisan

Message 9 of 10
MagWeb
in reply to: MagWeb

Hmm, can confirm your issue. As it works mostly but not always: Seems this needs some time to analyse.

 

About the boolean way: If you somehow copy the middle group as a separate object and close its holes to use it to do a BooleanDifference there a redundant surfaces. As long as these are planar MM might handle this in a Boolean. If they are non planar you'll see Booleans fail (endless intersections). So after closing the holes you might want to extrude its exterior surface to be bigger than the original.



Gunter Weber
Triangle Artisan

Message 10 of 10
MagWeb
in reply to: MagWeb

No clue yet why this flipping happens and why the surfaces aren't selectable after splitting the complex (even with AllowBackFaces enabled). This seems to be some bug or at least an unhandled exception.

 

But I found a workaround:

After splitting, export the object with flipped surfaces to .OBJ and import back. Now you can select (AllowBackFaces enabled) the flipped surfaces by double click and do Edit/FlipNormals. Interesting: After flipping those regions show up in white (= no group).



Gunter Weber
Triangle Artisan

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