How to prepare an object for successful boolean?

[benhull]

Hi there

I keep finding my objects don't boolean successfully. I have grasped how to do a boolean and got it working with some of the basic polygon objects.

The problem is have is after manipulating or making my own polygon object, the boolean fails, but I get no explanation about why.

I've heard about booleans failing if the object isn't 'watertight' but how can I check that, and how can I solve that? And are there any other issues that might be causing the failure that I can check into?

Attached are the two objects I'm trying to boolean - when I try it, they both disappear, whichever order in the boolean they sit.

Thanks in advance!

 

[frank beckmann]

Seems odd to me. The back looks suspicious though.
Maybe compare with my file:

Check objects info about watertightness.

Cheers
Frank

 

[Swizl]

You can go to Tools > Object Info (Command-I) to see if your object is watertight.

It may be helpful to also run an Optimize (Tools > Polygon > Optimize)on your mesh. Settings for Optimize show up in the Tool palette. Although you may have to be careful depending on the size of your mesh if the vertices are close enough to weld and also that it doesn't drastically modify your mesh if you need it exact.

Edit:
Ha, Frank to the rescue as I was typing.

 

[frank beckmann]

Nah - good tip on the Optimize tool - but I was guessing it has its nativity as a box - from what I read.

Cheers
Frank

 

[benhull]

Thanks guys. Just realised I was using the boolean modifier instead of boolean creator. I don't yet understand why that would matter, but using the boolean creator works just fine.

 

[frank beckmann]

That in essence doesn´t make a difference as I used the modifier in my uploaded file.
You might check the set-up closely.

Cheers
Frank

 

[benhull]

Oh. Do you use them the same way? Drag/drop both objects into the boolean layer?

If I drag drop the two objects between the boolean creator and the boolean modifier, it definitely works in the creator and not in the modifier. Odd.

 

[frank beckmann]

The Boolean-modifier hierarchy changed with release of v7.
You add the B-modifier to your first object and add further ones to that modifier.
Please see into menu->Help->Cheetah3d samples->Modeling->Boolean.jas to get the idea.

Cheers
Frank

 

[BillG]

I'm still really struggling with booleans. Have been a Cheetah3D user for a long time, and now with a new MacPro, I'm trying to transition my work to v7.3.1.

I can subtract a sphere from a cube OK, but it fails if the original geometry has higher complexity. Typically using a capsule or a cube, with some minor adjustments such as bevelled edges or a couple of ring cuts , covers and moves, then a shell modifier. I'm trying to create a cutaway type drawing, so using the boolean modifier in the new hierarchy, subtracting a polyhedron which has been linear subdivided once and crumpled to create the cutaway shape.

By moving the polyhedron around, sometimes it works, sometimes the shell modifier doesn't work, sometimes I see just the polyhedron, and sometimes I see neither object.

I tried optimizing, and it says that it is watertight. What am I missing?

 

[Swizl]

Are you opening an older file in v7? I've had some weirdness with that and booleans. Try to copy and paste them into a new document. If you are creating these in v7 from scratch, it's harder to guess what might be causing it.

Could it be twisted Polygons? (screenshot from the manual)

 

[frank beckmann]

Could it be twisted Polygons?

If is the case try "Triangulate" property of the Boolean modifier/creator and see if this helps.
Otherwise simply upload your file and we will see why it´s not working as expected.
This is a hack on a polyhedra:

Cheers
Frank

 

[BillG]

Looks like Triangulate fixed it. Thanks, Frank!!

Here is the file, so you can see. Drag the polyhedra on the X axis. As I was putting it together to send here, I was dragging the polyhedra in the Z axis (untriangulated), and it crashed Cheetah3D after a few moves.

 

[Vorsos]

I don't see watertight mentioned in the Boolean documentation, but I can confirm it matters. This plane array failed in every boolean arrangement with a swept frame, until I added a very thin shell.


Does the creator or modifier boolean have inherent advantages, or do they just facilitate how our various objects are organized?