Incorrect geometry with boolean operator #53999

New Issue

Paul Melis · 2018-02-05T14:33:11+01:00

Paul Melis commented

2018-02-05 14:33:11 +01:00

System Information

Arch Linux, GTX Titan

Blender Version

2.79a release candidate from blender.org

Short description of error

I have an object from which I subtract a cylinder, using a boolean difference modifier. Some of the edges of the resulting mesh are incorrect. The base object was also produced with a boolean difference, so maybe there is something wrong at that level already.

Exact steps for others to reproduce the error

See attached .blend. The result of t hole in the hemispherical object is not round. There's 4 edges that

**System Information** Arch Linux, GTX Titan **Blender Version** 2.79a release candidate from blender.org **Short description of error** I have an object from which I subtract a cylinder, using a boolean difference modifier. Some of the edges of the resulting mesh are incorrect. The base object was also produced with a boolean difference, so maybe there is something wrong at that level already. **Exact steps for others to reproduce the error** See attached .blend. The result of t hole in the hemispherical object is not round. There's 4 edges that

Paul Melis commented

2018-02-05 14:33:11 +01:00

Added subscriber: @PaulMelis

blender-admin commented

2018-02-05 14:33:11 +01:00

#54181 was marked as duplicate of this issue

Paul Melis commented

2018-02-05 14:36:39 +01:00

(Ahum, submitted too soon :))

See the screenshot. There are four of these strange edges. The selected face actually seems to be drawn incorrectly with respect to its actual edges.

boolean_bug.blend

(Ahum, submitted too soon :)) See the screenshot. There are four of these strange edges. The selected face actually seems to be drawn incorrectly with respect to its actual edges. [boolean_bug.blend](https://archive.blender.org/developer/F2130854/boolean_bug.blend) ![ss.png](https://archive.blender.org/developer/F2130863/ss.png)

ronan ducluzeau commented

2018-02-06 14:14:46 +01:00

Added subscriber: @zeauro

ronan ducluzeau commented

2018-02-06 14:14:46 +01:00

There are worst bugs already listed about overlapping geometry.
I am not sure if this case of a shell should be considered as a duplicate or a different case.

Anyways, it is just a wrong choîce to triangulate an Ngon. User can easily fix this by adding a triangulate modifier after Boolean modifier or on Cylinder operand.

There are worst bugs already listed about overlapping geometry. I am not sure if this case of a shell should be considered as a duplicate or a different case. Anyways, it is just a wrong choîce to triangulate an Ngon. User can easily fix this by adding a triangulate modifier after Boolean modifier or on Cylinder operand.

Sergey Sharybin commented

2018-02-07 15:53:04 +01:00

Added subscriber: @Sergey

Campbell Barton was assigned by Sergey Sharybin

2018-02-07 15:53:04 +01:00

Sergey Sharybin commented

2018-02-07 15:53:04 +01:00

Apparently, happens with both Carve and BMesh boolean implementations. @campbellabrton, are you up for looking into this issue? :)

Campbell Barton commented

2018-02-08 02:13:48 +01:00

Added subscriber: @mont29

Campbell Barton commented

2018-02-08 02:13:48 +01:00

This is not really related to booleans, it's more that quads always tessellate first to third vertices.
This has been reported before and we've closed as known-limitation/behavior.

This was because we used to use GL_QUAD (in 2.8x this is no longer the case), so the order of tessellation wasn't defined,
In fact on some ATI cards this would show correctly.

Since 2.8x defines tessellation, it's probably best we support concave quads (as we do concave ngons).

Submitted D3052 to support this, would like to get feedback from @mont29 since this has implications elsewhere (exporters for eg).

This is not really related to booleans, it's more that quads always tessellate first to third vertices. This has been reported before and we've closed as known-limitation/behavior. This was because we used to use `GL_QUAD` *(in 2.8x this is no longer the case)*, so the order of tessellation wasn't defined, In fact on some ATI cards this would show correctly. Since 2.8x defines tessellation, it's probably best we support concave quads (as we do concave ngons). Submitted [D3052](https://archive.blender.org/developer/D3052) to support this, would like to get feedback from @mont29 since this has implications elsewhere (exporters for eg).

Campbell Barton commented

2018-02-08 13:49:12 +01:00

Changed status from 'Open' to: 'Resolved'

Campbell Barton closed this issue

2018-02-08 13:49:12 +01:00

Campbell Barton commented

2018-02-08 13:49:12 +01:00

Fixed f088c6b9f6

Although this won't be for 2.79a since we need to see it doesn't cause issues for animators.

Fixed f088c6b9f6 Although this won't be for 2.79a since we need to see it doesn't cause issues for animators.

Campbell Barton commented

2018-02-27 03:10:14 +01:00