Non-Manifold Geometry: Your BIGGEST Issue when using Booleans (Blender Tutorial)

[@lawrencedoliveiro9104]

1:22 Don’t bother with that addon. Use Blender’s built-in “Select → Select All By Trait → Non Manifold” function in Mesh Edit mode instead. The advantage is the Redo box for this operation lets you isolate all the different ways that a mesh can be non-manifold, along with the specific parts that are causing the trouble, so that you can make the appropriate fixes to them.

[@NickFish117]

Whenever I ran into this problem I would always just give in and apply the mirror. It makes so much sense now! Thanks Josh

[@JoshGambrell]

Glad it helps man!

[@bl4ckpinky]

Non-manifold geometry means, an edge is part of 3 or more face, which is physical impossible. It breaks a lot of modeling operations and should be avoided or fixed. What you demonstrated in your video is the intended difference between a volume(closed mesh) and a surface(open mesh).

[@hemakodaaa]

Wait, does this mean that non-destructive workflow is basically working on an imaginative geometry? So all those arrays, mirrors, and booleans are just a figment of my imagination? Is anything real anymore? I expected a blender tutorial and what I got is a test of faith. Great video 😂

[@nibblrrr7124]

While it's not the core issue Josh wanted to get at, I thought that bit is easily misunderstood. After the mirror modifier in the stack, the geometry is just as real as if you modeled it destructively, even if you don't apply the modifier. (It's just not accessible via Edit mode.) It's not like it's a bug in Blender; the modifiers work as intended here & respect the order in which they are in the stack. The problem here was that the Boolean modifier came before the mirror modifier. The mirrored geometry wasn't "imaginary" or "theoretical" or any complicated distinction like that - at that point, it literally didn't exist yet in the stack when the Boolean got to it.

[@TechnicalJatin1]

@@nibblrrr7124 finally Someone Here like me Who Got This Understanding After Watching This Video ! Cheers 🍻

[@nicolasneumann1886]

there is no spoon

[@AlexLupoz]

Last night a DJ saved my life, but today, you saved my life, bro! Thanks, MANY MANY MANY thanks ♥🙏

[@maxparkervfx]

Can this video itself be the basis of a new religion?

[@webdraftdesign]

Yes...

[@pixel_arc8550]

Everything can. At least most religions are based on a fictional book full of fairy tales and lies. If thats enough to make people believe in something, this video certainly can do much more.

[@GenericInternetter]

3:00 I'm pretty sure you get the "half-and-half" problem there because the face is facing outward from the right side of the cube, causing the right half to be watertight. But when the software checks the left half, there's no face pointing outwards there which is why that half isn't watertight. I haven't checked this, but I would check by making a cube, checking it's watertight, then inverting the face normal on one of the faces, then checking again. My prediction (as described above) is that the cube with one inverted face would no longer be watertight. Basically it looks like watertightness takes into account the face normals, and faces pointing the wrong way don't give watertightness. Later on at 5:35 the problem appears to go away with the internal face because the mirror modifier is also mirroring that face, giving you basically two separate watertight cubes. I think the confusion arises because the two cubes are touching. If you move the cube away from the mirrored axis, you'll see it is simply two watertight cubes.

[@lRAQl]

This is what I was thinking the whole video!!!! I was waiting for Josh to blame it on the blue and red normal facing!

[@hunter8071]

put in mind that the addon you're using automatically puts boolean before mirror so the boolean doesn't consider the mirrored part as geometry which causes this issue so you can just put the mirror above and then you don't have to apply it. but really thanks for explaining what Non-Manifold geometry means.

[@Danzinger94]

You solved my long time problem. Now I understand and precisely do whats necessary instead of trying random operations. Thank you Josh very much!

[@JoshGambrell]

No problem, glad to help!

[@AArmstrongC]

I cleaned up a 3D scan, and I manually cleaned the non-manifold geo, but I couldn't quad remesh because it was non manifold somehow. The "Check all" tool didn't recognize any nonmanifold geo but! In that same addon, in the cleanup section there is a magic "MAKE MANIFOLD" button :) that solved the issues for me

[@DarthGamer00]

Thank you so much dude. I've been having issues with my booleans for months now and could never figure it out.

[@JoshGambrell]

Happy to help!

[@HomeWithDrew]

You explained it perfectly as to what the issue is, and perfectly explained how to solve it

[@orthodoxNPC]

another reason things become non-manifold is one normal not matching the direction of the rest of the normals that encapsulate a void

[@kvstxr]

I was Making an I mac and i wanted to Make a Hole in the stand and it was having mirror modifier and then i was stuck of this glitch so i was very frustrated and thought i would figure out someother time and now i saw this and realise what to do SO very Thank you For this I gave a thumbs up

[@varunc4746]

This was my main problem I was facing and now I understood the problem.

[@NathanChojnacki]

great tip man, I haven't run into this issue personally but I felt it coming, and this makes perfect sense. Thanks!

[@dewdeeee]

THANK YOU SO MUCH YOU SAVED HOURS OF MY WORK!!!! I had a problem that when i export 3d model from blender that looked normal inside of blender turned into some monstrocsity anyway it helped and wanted to say thank you one more time

[@naveenthikshana4223]

Josh Thank you, I faced 100 times while I working with Mirror modifier

[@AndrewCadwell]

I was struggling a lot with this, thank you very much!

[@reVarmed]

My workflow regarding this problem is to make sure the mirror is first in modifiers stack and all the booleans are placed after it

[@HomeWithDrew]

I recently found that plugin too which is wish I found when I started as I learned blender for 3d printing

[@laljaka]

I'm not sure as I don't do hard surface much, but isn't turning clipping on in the mirror modifier will fix it as well?

[@FullMe7alJacke7]

Seems pretty simple, mirrored geometry isn't real until it's applied.

[@mordfustang1933]

Biggest things that helped me with booleans / hard surfaces is. Are transformations applied? Normals recalculated, and Boolean at top of stack if possible.

[@mikelgrenlou558]

That's why I usually like to use hard ops symmetry, pretty handy

[@the3dsmith]

Super helpful explanation.. I was struggling with Boolean on a part I added a type of “texture” too… now that I think about it, the “texture” bit, should be done after the Boolean not before. Why? It’s not a manifold! 👍

[@Nexxorcist]

started watching this video before i started encountering it hardcore and i referred back to it and it helped so much. thank you! it was like you reading my mind! lol

[@TurboThunderbolt]

another fix you could do without needing a face on the inside is to move the boolean modifier below the mirror modifier

[@JoshGambrell]

Sure, but that wasn't the point. Doing that won't teach what is actually happening behind the scenes - the goal of this vid :)

[@TurboThunderbolt]

@@JoshGambrell that is fair

[@BenMelluish]

Has the mirror thing been fixed? Just tried it in Blender 2.90.1 and the cut works after a mirror.

[@EPmessi9800]

This was literally my main issue but then I guess I figured out how to solve it after asking around.

[@danhu4465]

Are you sure this video was made for beginners? Coz I can't even find that cutting tool anywhere

[@gammr3227]

how does the mirror modifier help? it just duplicates the object.

[@nibblrrr7124]

Is there an option in HardOps to place new cutter Booleans after the mirror in the modifier stack? Placing it before the mirror by default seems like the intended thing that saves you incredible amounts of time in 99% of cases, but in 1% of cases it causes a bit of a headache if you don't understand what it's actually doing on the modifier stack.

[@odracir3300]

if I join two objects with faces (that encapsulate the space inside) can I use this technique to give it volume, for same Boolean results i.e.??

[@varunc4746]

Can you make a video on what will we do after the model is finished and the sub division modifiers are still present in the stack and if we apply it there will be a lot of geometry and how can we lower the number of vertices. Is it by decimate modifier or any other way.

[@MineLoom]

Is there a plugin or a way to highlight the manifold geometry, similar to maya's cleanup tool?

[@JoshGambrell]

3D-Print Toolbox or built in selection options.

[@JYwyd7866]

hi there, how did you do the cut at the middle of the cube?

[@JoshGambrell]

Boxcutter plugin!

[@awkward14]

Thanks for the good explanation

[@Dredenot]

Wouldn't this issue be fixed by checking the "Clipping" option in the mirror modifier? I always have it enabled and I've never encountered this problem. I've also tried to replicate what you did in the video and my cube looked fine after bool even with non manifold geo and clipping disabled.

[@JoshGambrell]

Well it all depends on order of modifier stack and the object at hand. All clipping does is stop the mirror from passing its overlap point. The point here was to demonstrate what non-manifold geometry is because I see people encounter this all the time. I want people to understand what is happening so they can diagnose and fix more complex issues, not cheat their way out by finding a box to tick. Intuition and understanding is key to being an efficient 3D artist :)

[@nibblrrr7124]

_Merge_ is the important option (making it not duplicate the vertex on the mirror plane, but instead connect the edges from both sides to the exact same vertex), and it was on. Clipping just ensures the points stick to the mirror plane once you move them there while editing. The problem is the order in the stack - the Boolean modifier comes before the mirror modifier, when that geometry doesn't exist yet, and there's a hole in the middle. I think this is what Josh was trying to get at with "imaginary geometry".

[@torjusaanderaa3749]

Thanks for all you're great help with boolean issues that can be such a pain! wouldn't putting the boolean AFTER the mirror modifier in the stack also solve this? cause modifiers should read geometry created by previous modifiers as just as real as any other right? in this example it's not "real" because it's applied after the boolean an therefor does not exist from it's point of view. But isn't it much better to fix the stack than applying the mirror?

[@SlyNine]

Clipping wouldn't work? Are you just referring to boolean in edit mode?

[@JoshGambrell]

All clipping does is stops the mirror from passing its overlap point. Doesn't change the topics mentioned in this video. I turned on clipping and the issue still occurs.

[@SlyNine]

@@JoshGambrell I haven't really played with booleans. But I thought if you used the boolean modifier after the mirror modifier it would work. Then again, my memory sucks.

[@JoshGambrell]

@@SlyNine Well you can always use the modifier stack for quick fixes. But what's the point if you don't understand the underlying problem? It's important so you're able to fix more complex issues relating to this topic, hence why I showed the problem itself and not some quick fix with no backend understanding.

[@SlyNine]

@@JoshGambrell I do get your point about non manifold geometry. I think you clearly stated it. It was just the mirror modifier clipping thing that threw me off.

[@kitsaws213]

how are your vertices so bold?

[@JoshGambrell]

Edit->Preferences->Themes->3D Viewport->Vertex Size

[@RonHicks]

It looks like the non destructive workflow needs to be more robust. Thanks for the tip Josh.

[@splashinglures]

what about a manifold external face?

[@joeblogs6830]

nice one thanks grate vid

[@lamchingho662]

imo non manifold means blender (or any 3d software) dont know if a face (or plane) is facing outwards or inwards. in order for boolean modifiers to work correctly every single face should have one side that is outside the mesh and another side that is inside the mesh. some common way to fix it is to use solidify modifier if u have a plane surface, or use shift+n (recalculate normals) and merge vertices by distance to clean up ur model. p.s. u can choose to use the boolean modifier and put it under the mirror modifier to avoid non manifold boolean issues

[@AbdulAziz-co8rm]

what is “watertight”? 1:00

[@Ozification]

Watertight is when the model is completely solid and you cant see the back of any faces. Think of dunking your model in water, if you have any holes in your model then water will seep into it. This is bad when trying to slice a model for 3d printing and some animation.

[@Drums712]

Excellent! Thank you!

[@gammr3227]

the menu doesnt appear when i select the addon.

[@kolupsy]

For everybody thinking of filling in the faces on a mirrored edge like shown in the video, be aware that this is a really bad idea for nearly all Workflows. When you add a subsurf modifier for example, this will cause the mesh to make really weird and undesirable stuff. So only do it for this kind of workflow here

[@JM_Design3D]

Eres el mejor. El número uno.

[@Dalek-br6nu]

Your title should specify that this video is about when using the mirror modifier, it's completely irrelevant if you're not.

[@Draft_Tech]

Thanks josh...noted

[@someshsahu4638]

Nice video thankyou sir

[@faranell7481]

But wouldn't that inside face cause shading issues with smooth shading turned on?

[@JoshGambrell]

Auto smooth man

[@faranell7481]

@@JoshGambrell On a cube it works perfectly, but if I mirror other shapes (a sphere for example), the issue is still visible. With autosmooth I got rid of the weird shadows, but there is still a big seam along the line of the inner face (almost like an UV seam).

[@Oleksandr_Minakov]

I try find another solution. So if jast duplicate mirror modifier and move top, looks good. And the same time mesh not manifold. But it can be a make another problems in future with modificators.

[@waffel7664]

no mirrored objects and no non-manifold edges, yet it still doesn't work :/

[@lawrencedoliveiro9104]

1:00 Basically, a non-manifold mesh cannot be the surface of a real, physical object.

[@tovape]

damn thanks very helpful!

[@Raul-ef6ct]

it did help out

[@TheRealFancyGaming]

Can find this add on

[@MaximumAbility]

I don't understand why developers creating a tab like a 3D Print and can't create a tab for grouping all items into one and for simplicity to add in the addon preferences to chose where I want to place this addon. This is a tool and I will put this into Tool section, because when a lot of addons are activated the properties panel is full and sometimes it will grow until you see for every section just one letter and no more. P.S. The same you see? Hard Ops and Boxcutter into different tabs? Really? Kit Ops ... Machin3.........

[@3dmodeling101]

This video explains 7 different non-manifold issues and how to fix them all. See kzbin.info/www/bejne/bWnKqnduareFoNE

[@captain_code]

Duuuuuude, i had this exact problem a few days ago. I figured out tho.

[@pixelrabbit261]

OMG, life saver. Just been trying to manually stitch everything together... {'_'}

[@sevenseven31]

try to cut with orthographic view

[@gammr3227]

mirror modifier literally just duplicates my object and doesnt remove non manifold edges. Bad tutorial.

[@CLAYTERRACOTTA]

Im the first comment Poggers

[@sirkuchen1501]

Oof true

[@Mercento]

why the f do people keep using 'water tight' to explain manifold??? it makes not sense at all!

[@vladisslavss]

Like and commented!)

[@gammr3227]

literally useless if you want anything that isnt a literal cube.