Adding two planes != separating two faces of a cube? (boolean modifier) #38797

New Issue

gandalf3 · 2014-02-24T09:29:36+01:00

gandalf3 commented

2014-02-24 09:29:36 +01:00

System Information
Archlinux
Nvidia GTX 460

Blender Version
Broken: 10f4c26 (2.7 RC)

Short description of error
Creating a boolean modifier setup with two planes boolean joined subtracting from a cylinder (see http://blender.stackexchange.com/a/7285/599 for context) does not give the same result when created different ways. Using a cube gives the expected result, while directly adding planes does not.

Exact steps for others to reproduce the error
In the attached .blend boolean_plane_v_cube.blend:

layer 1: Boolean operation set up by adding planes
layer 2: Boolean operation set up by adding a cube

Exact setup steps:

For planes:

Add plane
R+X+90
G+X+1
Add plane
R+Y+90
G+Y+1
Add boolean join modifier to plane 1 with plane 2 as target
Add cylinder
Add boolean difference modifier to cylinder with plane 1 as target

For cube:

Add cube
Move cube with snapping so one edge is in the world center
Delete top and bottom vertices on the edge opposite edge in the world center
Select one of the remaining two faces and separate by selection
Add boolean join modifier from separated face to other face
Add cylinder
Add boolean difference modifier to cylinder with separated face as target.

**System Information** Archlinux Nvidia GTX 460 **Blender Version** Broken: 10f4c26 (2.7 RC) **Short description of error** Creating a boolean modifier setup with two planes boolean joined subtracting from a cylinder (see http://blender.stackexchange.com/a/7285/599 for context) does not give the same result when created different ways. Using a cube gives the expected result, while directly adding planes does not. **Exact steps for others to reproduce the error** In the attached .blend [boolean_plane_v_cube.blend](https://archive.blender.org/developer/F78711/boolean_plane_v_cube.blend): * layer 1: Boolean operation set up by adding planes * layer 2: Boolean operation set up by adding a cube **Exact setup steps:** For planes: 1. Add plane 2. R+X+90 3. G+X+1 4. Add plane 5. R+Y+90 6. G+Y+1 7. Add boolean join modifier to plane 1 with plane 2 as target 8. Add cylinder 9. Add boolean difference modifier to cylinder with plane 1 as target For cube: 1. Add cube 2. Move cube with snapping so one edge is in the world center 3. Delete top and bottom vertices on the edge opposite edge in the world center 4. Select one of the remaining two faces and separate by selection 5. Add boolean join modifier from separated face to other face 6. Add cylinder 7. Add boolean difference modifier to cylinder with separated face as target.

gandalf3 commented

2014-02-24 09:29:36 +01:00

Changed status to: 'Open'

gandalf3 commented

2014-02-24 09:29:36 +01:00

Added subscriber: @gandalf3

Brecht Van Lommel commented

2014-02-24 12:51:00 +01:00

Changed status from 'Open' to: 'Archived'

Brecht Van Lommel closed this issue

2014-02-24 12:51:00 +01:00

Brecht Van Lommel self-assigned this 2014-02-24 12:51:00 +01:00

Brecht Van Lommel commented

2014-02-24 12:51:00 +01:00

In this case face normals matter to determine what is inside or outside, since that cannot be determined automatically from a non-closed mesh.

gandalf3 commented

2014-02-24 12:57:16 +01:00

Added subscriber: @brecht

gandalf3 commented

2014-02-24 12:57:16 +01:00

@brecht But the shouldn't the result be the same? I don't understand how the method used to create the planes could affect it, as the objects/normals seem identical in the end (to me, anyway)..

Brecht Van Lommel commented

2014-02-24 14:49:52 +01:00

Changed status from 'Archived' to: 'Open'

Brecht Van Lommel reopened this issue

2014-02-24 14:49:52 +01:00

Brecht Van Lommel commented

2014-02-24 14:49:52 +01:00

Added subscriber: @Sergey

Brecht Van Lommel commented

2014-02-24 14:49:52 +01:00

I closed this one too fast, will let @Sergey have a look.

Brecht Van Lommel removed their assignment 2014-02-24 14:50:07 +01:00

Sergey Sharybin was assigned by Brecht Van Lommel

2014-02-24 14:50:07 +01:00

Sergey Sharybin commented

2014-02-24 15:10:15 +01:00

Changed status from 'Open' to: 'Archived'

Sergey Sharybin closed this issue

2014-02-24 15:10:15 +01:00

Sergey Sharybin commented

2014-02-24 15:10:15 +01:00

Your two ways of creating the operand doesn't match really. You're adding rotation to the planes which gives a bit of float precision issues, resulting in different location of vertices in the corner which might look being at the same exact point.

Root of the issues goes to the fact that Blender uses floats and Carve uses double, which results in different epsilons being considered all over..

Doesn't consider a bug, just a specific work.

Your two ways of creating the operand doesn't match really. You're adding rotation to the planes which gives a bit of float precision issues, resulting in different location of vertices in the corner which might look being at the same exact point. Root of the issues goes to the fact that Blender uses floats and Carve uses double, which results in different epsilons being considered all over.. Doesn't consider a bug, just a specific work.

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Adding two planes != separating two faces of a cube? (boolean modifier) #38797