Geometry Nodes Mesh Boolean unexpected difference result #103952

New Issue

Balázs Füvesi · 2023-01-17T23:13:15+01:00

Balázs Füvesi commented

2023-01-17 23:13:15 +01:00

System Information
Operating system: macOS-13.1-arm64-arm-64bit 64 Bits
Graphics card: Apple M1 Apple 4.1 Metal - 83

Blender Version
Broken: version: 3.5.0 Alpha, branch: master, commit date: 2023-01-16 22:58, hash: 7241ab6ede
Worked: none

Short description of error
Geometry Nodes Mesh Boolean Difference does not work as expected.
Node setup:

Unexpected boolean difference:

Exact steps for others to reproduce the error

Open the attached .blend file
Press G to move the selected Cube.001 and the small cubes will flicker.

At certain positions of Cube.001 some of the small cubes will disappear when they should not.

Thanks!
test06.blend

**System Information** Operating system: macOS-13.1-arm64-arm-64bit 64 Bits Graphics card: Apple M1 Apple 4.1 Metal - 83 **Blender Version** Broken: version: 3.5.0 Alpha, branch: master, commit date: 2023-01-16 22:58, hash: `7241ab6ede` Worked: none **Short description of error** Geometry Nodes Mesh Boolean Difference does not work as expected. Node setup: ![nodeSetup.png](https://archive.blender.org/developer/F14164794/nodeSetup.png) Unexpected boolean difference: ![incorrectBoolean.png](https://archive.blender.org/developer/F14164813/incorrectBoolean.png) **Exact steps for others to reproduce the error** - Open the attached .blend file - Press G to move the selected Cube.001 and the small cubes will flicker. # At certain positions of Cube.001 some of the small cubes will disappear when they should not. Thanks! [test06.blend](https://archive.blender.org/developer/F14164865/test06.blend)

Balázs Füvesi commented

2023-01-17 23:13:15 +01:00

Added subscriber: @fuvesib

Pratik Borhade commented

2023-01-18 05:04:54 +01:00

Changed status from 'Needs Triage' to: 'Confirmed'

Pratik Borhade commented

2023-01-18 05:04:56 +01:00

Added subscriber: @PratikPB2123

Miro Horváth commented

2023-01-18 11:08:53 +01:00

Added subscriber: @MiroHorvath

Miro Horváth commented

2023-01-18 11:08:53 +01:00

Even though disappearing is annoying, it's a bit daring to expect getting correct result when faces of both meshes are perfectly lined up in Y axis(check in Top view).

To get a correct result you have to scale Cube.001 in Y axis(in case this is the result you're expecting).

Even though disappearing is annoying, it's a bit daring to expect getting correct result when faces of both meshes are perfectly lined up in Y axis(check in Top view). ![image.png](https://archive.blender.org/developer/F14171132/image.png) To get a correct result you have to scale Cube.001 in Y axis(in case this is the result you're expecting). ![image.png](https://archive.blender.org/developer/F14171199/image.png)

Balázs Füvesi commented

2023-01-18 13:07:30 +01:00

Sorry for the confusion, I did indeed forget to scale Cube.001 in the Y axis slightly bigger.
However, I did not mean the cubes circled with green, which could be explained by floating point uncertainty and which is expected when the faces are close to each other. But the cube circled with red which is way further to be explained with a floating point error in my opinion.

It is possible to get a similar result when Cube.001 is scaled bigger on the Y axis than the small cubes.

Blend file for the above picture:
test08.blend

Sorry for the confusion, I did indeed forget to scale Cube.001 in the Y axis slightly bigger. However, I did not mean the cubes circled with green, which could be explained by floating point uncertainty and which is expected when the faces are close to each other. But the cube circled with red which is way further to be explained with a floating point error in my opinion. ![Ynotscaled.png](https://archive.blender.org/developer/F14171642/Ynotscaled.png) It is possible to get a similar result when Cube.001 is scaled bigger on the Y axis than the small cubes. ![Yscaled.png](https://archive.blender.org/developer/F14171674/Yscaled.png) Blend file for the above picture: [test08.blend](https://archive.blender.org/developer/F14171678/test08.blend)

Miro Horváth commented

2023-01-18 15:49:47 +01:00

@fuvesib I see, this is quite annoying, Boolean documentation says:

Only Manifold meshes are guaranteed to give proper results, other cases (especially “opened” meshes, Non-manifold but without any self-intersections) will usually work well, but might give odd glitches and artifacts in some cases.

... so it should give you proper result(while changing Cube.001 transformation) as both meshes are Manifold.

Exactly because of getting these kind of issues when working with Boolean, I typically separate all the meshes within one object by Loose Parts(P-key in Edit mode) and then assign GN modifier to each newly created objects to minimize problems, it's indeed automated with Python API.

@fuvesib I see, this is quite annoying, Boolean documentation says: > Only Manifold meshes are guaranteed to give proper results, other cases (especially “opened” meshes, Non-manifold but without any self-intersections) will usually work well, but might give odd glitches and artifacts in some cases. ... so it should give you proper result(while changing Cube.001 transformation) as both meshes are Manifold. Exactly because of getting these kind of issues when working with Boolean, I typically separate all the meshes within one object by Loose Parts(P-key in Edit mode) and then assign GN modifier to each newly created objects to minimize problems, it's indeed automated with Python API.

Balázs Füvesi commented

2023-01-21 23:03:49 +01:00

Thank you for the suggestions.

I found this issue when a complex node setup started crashing with 3.4. I was able to reduce the problem to the Boolean node.
The crash issue has been solved (#103072) however, the flickering remained.

Although this is quite a niche issue compared to the crash, I think it would be nice to have it solved sometime in the future. So I opened this new report for this incorrect difference issue.

Thank you for the suggestions. I found this issue when a complex node setup started crashing with 3.4. I was able to reduce the problem to the Boolean node. The crash issue has been solved (#103072) however, the flickering remained. Although this is quite a niche issue compared to the crash, I think it would be nice to have it solved sometime in the future. So I opened this new report for this incorrect difference issue.

Philipp Oeser removed the

Download

What's New

Blender Studio

Manual

Developers Blog

Documentation

Benchmark

Blender Conference

Development Fund

One-time Donations

Geometry Nodes Mesh Boolean unexpected difference result #103952

At certain positions of Cube.001 some of the small cubes will disappear when they should not.