Exact boolean leaves behind odd vertices once Applied #80310

New Issue

Jesse Yurkovich · 2020-09-01T05:42:55+02:00

Jesse Yurkovich commented

2020-09-01 05:42:55 +02:00

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: AMD FirePro W2100 ATI Technologies Inc. 4.5.13493 Core Profile Context FireGL 22.19.693.256

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-08-31 22:30, hash: 4e06afb0a1
Worked: (newest version of Blender that worked as expected)

Short description of error
The new Exact boolean seems to leave behind several odd vertices if you Apply the modifier in certain circumstances. Even without applying you can see shading artifacts if the boolean'd object has Smooth shading enabled on it.

It's difficult to determine where these verts are coming from… perhaps from internal triangulation of the mesh during boolean processing?

Exact steps for others to reproduce the error
exactbool-rogue_verts.blend

Open the provided .blend
- Contains a 32 sided cylinder with a 32 segment Torus subtracted from it using Exact mode
You can already see the issue if you enable "Smooth shading" for the cylinder
Apply the boolean
Go into Edit mode for the Cylinder and notice the following
- A Merge-by-Distance operation is required to remove 175 vertices (which is already odd; expected at most 64 really and ideally 0 to be removed)
- Rogue verts. See below:

**System Information** Operating system: Windows-10-10.0.19041-SP0 64 Bits Graphics card: AMD FirePro W2100 ATI Technologies Inc. 4.5.13493 Core Profile Context FireGL 22.19.693.256 **Blender Version** Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-08-31 22:30, hash: `4e06afb0a1` Worked: (newest version of Blender that worked as expected) **Short description of error** The new Exact boolean seems to leave behind several odd vertices if you Apply the modifier in certain circumstances. Even without applying you can see shading artifacts if the boolean'd object has Smooth shading enabled on it. It's difficult to determine where these verts are coming from… perhaps from internal triangulation of the mesh during boolean processing? **Exact steps for others to reproduce the error** [exactbool-rogue_verts.blend](https://archive.blender.org/developer/F8828031/exactbool-rogue_verts.blend) - Open the provided .blend - Contains a 32 sided cylinder with a 32 segment Torus subtracted from it using Exact mode - You can already see the issue if you enable "Smooth shading" for the cylinder - Apply the boolean - Go into Edit mode for the Cylinder and notice the following - A Merge-by-Distance operation is required to remove 175 vertices (which is already odd; expected at most 64 really and ideally 0 to be removed) - Rogue verts. See below: ![rougue-verts.png](https://archive.blender.org/developer/F8828028/rougue-verts.png)

Jesse Yurkovich commented

2020-09-01 05:42:55 +02:00

Added subscriber: @deadpin

blender-admin commented

2020-09-01 05:42:55 +02:00

#81025 was marked as duplicate of this issue

Philipp Oeser commented

2020-09-01 14:54:49 +02:00

Added subscribers: @howardt, @lichtwerk

Philipp Oeser commented

2020-09-01 14:54:49 +02:00

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

Philipp Oeser commented

2020-09-01 14:54:49 +02:00

Can confirm.

@howardt : mind checking?

Can confirm. @howardt : mind checking?

Howard Trickey commented

2020-09-01 15:20:03 +02:00

Thanks, I will check it out.

Howard Trickey self-assigned this 2020-09-04 15:58:40 +02:00

Howard Trickey commented

2020-09-07 21:06:32 +02:00

The rogue vertices are, I think, remnants of diagonal intersections that were not removed, but I need to investigate this more.

The many unexpected merge-by-distance verts removed is, I think, because the torus and cylinder probably use slightly different math to make the matrices used during their formation, so the vertices don't coincide exactly. The new code is not trying to merge close vertices, so for now, that part is "working as intended" for the new code.

I will leave this open to see what is going on with the obviously rogue vertices.

The rogue vertices are, I think, remnants of diagonal intersections that were not removed, but I need to investigate this more. The many unexpected merge-by-distance verts removed is, I think, because the torus and cylinder probably use slightly different math to make the matrices used during their formation, so the vertices don't coincide exactly. The new code is not trying to merge close vertices, so for now, that part is "working as intended" for the new code. I will leave this open to see what is going on with the obviously rogue vertices.

fwfeet commented

2020-09-21 12:05:50 +02:00

Added subscriber: @costa

Howard Trickey commented

2020-10-11 15:55:15 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Howard Trickey closed this issue

2020-10-11 15:55:15 +02:00

Howard Trickey commented

2020-10-11 15:55:15 +02:00

Commit 16ca295278 fixed the merged in bug, #81025 . The rogue vertices in the example of this bug are only seemingly rogue. There are actually some very skinny triangles that use them. This is the result of the same issue noted above: different math for torus and cylinder leading to very slightly different vertex positions.

Commit 16ca295278 fixed the merged in bug, #81025 . The rogue vertices in the example of this bug are only seemingly rogue. There are actually some very skinny triangles that use them. This is the result of the same issue noted above: different math for torus and cylinder leading to very slightly different vertex positions.

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Exact boolean leaves behind odd vertices once Applied #80310