Boolean issues when duplicating and rotating mesh or object #82047

New Issue

Robbie K. · 2020-10-25T02:53:06+01:00

Robbie K. commented

2020-10-25 02:53:06 +01:00

System Information
Operating system: Windows-7-6.1.7601-SP1 64 Bits
Graphics card: GeForce GTX 1050 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.30

Blender Version
Broken: version: 2.91.0 Beta, branch: master, commit date: 2020-10-23 17:33, hash: 70cc0d7121
Worked: (newest version of Blender that worked as expected)

Exact steps for others to reproduce the error
Not sure if this is a boolean issue or an issue with accuracy when rotating. Scale a cube in the x or y direction, duplicate that cube and rotate it along the z-axis 90 degrees forming an X. Apply a boolean difference on it using the new algorithm and swap between the two. One will completely subtract the other but not the other way around. But if you move one cube in the z direction and snap it back it will boolean each other correctly.

Or
boolean_rotated_box.blend

Open file
Boolean seems to not be working correctly
enter editmode on Cube
{key R X 90}
Boolean seems to be working correctly

**System Information** Operating system: Windows-7-6.1.7601-SP1 64 Bits Graphics card: GeForce GTX 1050 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 436.30 **Blender Version** Broken: version: 2.91.0 Beta, branch: master, commit date: 2020-10-23 17:33, hash: `70cc0d7121` Worked: (newest version of Blender that worked as expected) **Exact steps for others to reproduce the error** Not sure if this is a boolean issue or an issue with accuracy when rotating. Scale a cube in the x or y direction, duplicate that cube and rotate it along the z-axis 90 degrees forming an X. Apply a boolean difference on it using the new algorithm and swap between the two. One will completely subtract the other but not the other way around. But if you move one cube in the z direction and snap it back it will boolean each other correctly. Or [boolean_rotated_box.blend](https://archive.blender.org/developer/F9180734/boolean_rotated_box.blend) - Open file - Boolean seems to not be working correctly - enter editmode on `Cube` - {key R X 90} - Boolean seems to be working correctly

Robbie K. commented

2020-10-25 02:53:06 +01:00

Added subscriber: @RobbieK

Philip Holzmann commented

2020-10-25 10:09:05 +01:00

Added subscriber: @Foaly

Philip Holzmann commented

2020-10-25 10:09:05 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Philip Holzmann commented

2020-10-25 10:09:05 +01:00

I cannot reproduce.
Following your instructions, everything works correctly.

Please upload a file that illustrates your issue.

I cannot reproduce. Following your instructions, everything works correctly. Please upload a file that illustrates your issue.

Robbie K. commented

2020-10-25 18:46:26 +01:00

I tried it with bool tool in object mode and it worked this time for some reason. Scale the cube in edit mode and use boolean intersect and you get the issue.

It should look like this.

Update 1: I figured out why it didn't work in object mode last time. I separated one of the meshes and tried bool tool on both objects and it had the same problem. But moving one object in the z direction and snapping it back didn't fix the issue in object mode like it did it edit mode.

Update 2: I tried it again in edit mode and moving one mesh in the Z direction and snapping it back no longer works to fix the problem anymore.

Update 3: Snapping the upper and lower faces of one mesh to the other fixes the problem.

I tried it with bool tool in object mode and it worked this time for some reason. Scale the cube in edit mode and use boolean intersect and you get the issue. It should look like this. ![2020-10-25 13_50_50-Blender.jpg](https://archive.blender.org/developer/F9089830/2020-10-25_13_50_50-Blender.jpg) Update 1: I figured out why it didn't work in object mode last time. I separated one of the meshes and tried bool tool on both objects and it had the same problem. But moving one object in the z direction and snapping it back didn't fix the issue in object mode like it did it edit mode. Update 2: I tried it again in edit mode and moving one mesh in the Z direction and snapping it back no longer works to fix the problem anymore. Update 3: Snapping the upper and lower faces of one mesh to the other fixes the problem.

Philip Holzmann commented

2020-10-26 00:24:58 +01:00

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

Philip Holzmann commented

2020-10-26 00:24:58 +01:00

Added subscriber: @howardt

Philip Holzmann commented

2020-10-26 00:24:58 +01:00

I can confirm with 2.92.0 alpha e4728d0a16

The following file shows the issue.
boolean_rotated_box.blend

@howardt I think this is for you.

I can confirm with 2.92.0 alpha e4728d0a167c The following file shows the issue. [boolean_rotated_box.blend](https://archive.blender.org/developer/F9093612/boolean_rotated_box.blend) @howardt I think this is for you.

Philipp Oeser changed title from ~~boolean issues when duplicating and rotating mesh or object~~ to Boolean issues when duplicating and rotating mesh or object

2020-11-03 14:05:41 +01:00

Philipp Oeser commented

2020-11-03 14:05:41 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Confirmed'

Philip Holzmann commented

2020-11-08 12:32:57 +01:00

This seems to have been fixed in part recently.

However, if the box is scaled up a bit, and the boolean is applied multiple times, it can still cause issues.

See the attached file.
boolean_rotated_box2.blend

This seems to have been fixed in part recently. However, if the box is scaled up a bit, and the boolean is applied multiple times, it can still cause issues. See the attached file. [boolean_rotated_box2.blend](https://archive.blender.org/developer/F9235317/boolean_rotated_box2.blend)

Howard Trickey commented

2020-11-08 16:39:54 +01:00

Changed status from 'Confirmed' to: 'Resolved'

Howard Trickey closed this issue

2020-11-08 16:39:54 +01:00

Howard Trickey self-assigned this 2020-11-08 16:39:54 +01:00

Howard Trickey commented

2020-11-08 16:39:54 +01:00

The box with diagonals in boolean_rotated_box2.blend has y values that are almost, but not exactly +1 or -1. Here are the exact vertex coordinates (followed by what printing them as floating point gives):

11307515/2097152 4194317/4194304 -1 # -5.39184 1 -1
2826879/524288 -16777165/16777216 -1 # -5.39184 -0.999997 -1
2826879/524288 -16777165/16777216 1 # -5.39184 -0.999997 1
11307515/2097152 4194317/4194304 1 # -5.39184 1 1
2826879/524288 16777165/16777216 -1 # 5.39184 0.999997 -1
11307515/2097152 -4194317/4194304 -1 # 5.39184 -1 -1
2826879/524288 16777165/16777216 1 # 5.39184 0.999997 1
11307515/2097152 -4194317/4194304 1 # 5.39184 -1 1
756655/1048576 8388611/8388608 -1 # -0.721602 1 -1
6053245/8388608 16777209/16777216 1 # 0.721603 1 1
756655/1048576 -8388611/8388608 -1 # 0.721602 -1 -1
6053245/8388608 -16777209/16777216 1 # -0.721603 -1 1

So the two cubes do not line up in a way to give a nice cube-like intersection, and I don't see a bug here.
In general, when you do rotates and scales, the coordinates are multiplied by matrices with floating point values and it is to be expected that even though you think an operation should not affect a particular coordinate, it can do that in minuscule ways. I'm going to close this now. Feel free to reopen if there's a case where the input coordinates exactly line up (in this case: all y and z values should be exactly the same on both objects) and boolean fails.

The box with diagonals in boolean_rotated_box2.blend has y values that are almost, but not exactly +1 or -1. Here are the exact vertex coordinates (followed by what printing them as floating point gives): - 11307515/2097152 4194317/4194304 -1 # -5.39184 1 -1 - 2826879/524288 -16777165/16777216 -1 # -5.39184 -0.999997 -1 - 2826879/524288 -16777165/16777216 1 # -5.39184 -0.999997 1 - 11307515/2097152 4194317/4194304 1 # -5.39184 1 1 2826879/524288 16777165/16777216 -1 # 5.39184 0.999997 -1 11307515/2097152 -4194317/4194304 -1 # 5.39184 -1 -1 2826879/524288 16777165/16777216 1 # 5.39184 0.999997 1 11307515/2097152 -4194317/4194304 1 # 5.39184 -1 1 - 756655/1048576 8388611/8388608 -1 # -0.721602 1 -1 6053245/8388608 16777209/16777216 1 # 0.721603 1 1 756655/1048576 -8388611/8388608 -1 # 0.721602 -1 -1 - 6053245/8388608 -16777209/16777216 1 # -0.721603 -1 1 So the two cubes do not line up in a way to give a nice cube-like intersection, and I don't see a bug here. In general, when you do rotates and scales, the coordinates are multiplied by matrices with floating point values and it is to be expected that even though you think an operation should not affect a particular coordinate, it can do that in minuscule ways. I'm going to close this now. Feel free to reopen if there's a case where the input coordinates exactly line up (in this case: all y and z values should be exactly the same on both objects) and boolean fails.

Philip Holzmann commented

2020-11-08 20:28:22 +01:00

Maybe there is a misunderstanding here:
I'm not talking about the long stretched flat faces that remain, the issue is that a part of the mesh on the right disappears.

Otherwise, can we define the cases in which the exact boolean is supposed / not supposed to work then?

All the meshes in the example are manifold, but the boolean cuts away pieces that are not within the "brush".
If the self option is enabled, the resulting mesh is no longer manifold.

Maybe there is a misunderstanding here: I'm not talking about the long stretched flat faces that remain, the issue is that a part of the mesh on the right disappears. Otherwise, can we define the cases in which the *exact boolean* is supposed / not supposed to work then? All the meshes in the example are manifold, but the boolean cuts away pieces that are not within the "brush". If the self option is enabled, the resulting mesh is no longer manifold.

Howard Trickey commented

2020-11-08 22:36:33 +01:00

I am seeing this as the result:

I don't know what you mean by "part of the mesh on the right disappears".

If Cube had x and z values that exactly matched those of Cube.001, then we would expect that the whole center section would be gone when you subtract Cube from Cube.001. Since that isn't true, one has to examine the topology carefully to find out what parts of space are inside Cube.001 and not inside Cube. It is plausible to me that the two flat pieces in the middle are the parts of space that satisfy that, though I admit I didn't carefully verify that.

I am seeing this as the result: ![rotated.png](https://archive.blender.org/developer/F9240889/rotated.png) I don't know what you mean by "part of the mesh on the right disappears". If Cube had x and z values that exactly matched those of Cube.001, then we would expect that the whole center section would be gone when you subtract Cube from Cube.001. Since that isn't true, one has to examine the topology carefully to find out what parts of space are inside Cube.001 and not inside Cube. It is plausible to me that the two flat pieces in the middle are the parts of space that satisfy that, though I admit I didn't carefully verify that.

Philip Holzmann commented

2020-11-08 23:42:41 +01:00

I've been checking this with the latest builds from the buildbot: 2.91 beta 46da8e9eb958-windows64, 2.92 alpha 7be47dadea50-windows64.
I also built the latest master 39012146e1 myself.

What build are you using?

This is what I see in boolean_rotated_box2.blend in all 3 cases:

I've been checking this with the latest builds from the buildbot: 2.91 beta 46da8e9eb958-windows64, 2.92 alpha 7be47dadea50-windows64. I also built the latest master 39012146e142bf400c7140d90ecfd27c45b589ca myself. What build are you using? This is what I see in boolean_rotated_box2.blend in all 3 cases: ![boolean_rotated_box2.png](https://archive.blender.org/developer/F9241248/boolean_rotated_box2.png)

Philip Holzmann commented

2020-11-11 23:15:50 +01:00

@howardt Can this be reopened? I'm still getting the same wrong result with the latest 2.91 beta (2.91.0 4960780d76bf-windows64).

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Boolean issues when duplicating and rotating mesh or object #82047