3D-Print Toolbox intersection are not working as expected #80466

New Issue

Denis Cliofas · 2020-09-04T14:12:00+02:00

Denis Cliofas commented

2020-09-04 14:12:00 +02:00

System Information
Operating system: Windows 10
Graphics card: GeForce GTX 1080

Blender Version
Broken:2.90.0
Worked: 2.79b (2018-03-22 14:10, f4dc9f9d68b)

Addon Information
Name: 3D-Print Toolbox ()
Author: Campbell Barton

Short description of error
I have a mesh that visually looks correct but 3d-Print Toolbox is showing some intersection. The weird part is that if I move (or scale) all vertices in edit mode and recheck, the intersection number is changing and sometimes I can get even scenario with no intersection (without really changing the mesh).

The same mesh works perfectly fine if imported into 2.79.

Check gif:

Exact steps for others to reproduce the error

open attached blend file
select the only available object in scene
press "Check All" in 3D-print addon
check number of intersect faces
IntersectionBug.blend

**System Information** Operating system: Windows 10 Graphics card: GeForce GTX 1080 **Blender Version** Broken:2.90.0 Worked: 2.79b (2018-03-22 14:10, f4dc9f9d68b) **Addon Information** Name: 3D-Print Toolbox () Author: Campbell Barton **Short description of error** I have a mesh that visually looks correct but 3d-Print Toolbox is showing some intersection. The weird part is that if I move (or scale) all vertices in edit mode and recheck, the intersection number is changing and sometimes I can get even scenario with no intersection (without really changing the mesh). The same mesh works perfectly fine if imported into 2.79. Check gif: ![IntersectionBug.gif](https://archive.blender.org/developer/F8840097/IntersectionBug.gif) **Exact steps for others to reproduce the error** - open attached blend file - select the only available object in scene - press "Check All" in 3D-print addon - check number of intersect faces [IntersectionBug.blend](https://archive.blender.org/developer/F8840095/IntersectionBug.blend)

Denis Cliofas commented

2020-09-04 14:12:00 +02:00

Added subscriber: @denis-36

Daniel Grauer commented

2020-09-04 14:25:45 +02:00

Added subscriber: @DanielGrauer

Jacob Merrill commented

2020-09-04 18:05:39 +02:00

Added subscriber: @JacobMerrill-1

Oleg commented

2020-09-05 23:08:32 +02:00

Added subscriber: @agorka

Oleg commented

2020-09-05 23:08:32 +02:00

I'm having the same problem. I wanted to use self-intersection checking function to make some mesh randomization without self-intersecting, but getting lots of false-positive.

Seems the problem not in the addon itself but in mathutils.BVHTree functions:

  tree = mathutils.bvhtree.BVHTree.FromBMesh(bm, epsilon=0.00001)
  overlap = tree.overlap(tree)

I'm having the same problem. I wanted to use self-intersection checking function to make some mesh randomization without self-intersecting, but getting lots of false-positive. ![BlenderBug_img-2020-09-06-00-05-13.png](https://archive.blender.org/developer/F8845605/BlenderBug_img-2020-09-06-00-05-13.png) Seems the problem not in the addon itself but in mathutils.BVHTree functions: ``` tree = mathutils.bvhtree.BVHTree.FromBMesh(bm, epsilon=0.00001) overlap = tree.overlap(tree)

Henry S commented

2020-10-10 08:20:40 +02:00

Added subscriber: @DoubleHelix

Henry S commented

2020-10-10 08:20:40 +02:00

Using Blender 2.90.1 on Windows 10

I would just like to add this odd behavior I've noticed With the 3D Print Toolbox intersection check which seems related to this problem:

Open up a new scene.
Add a subdivision surface modifier to the default cube.
Set it to 'Simple' mode and the number of subdivisions to 5.
Apply the modifier.
Run the intersection check in 3D Print Toolbox.

This gives me a result of 112 intersections, despite this being a simple flat cube. The intersections seem to be random faces on the sides of the cube.

Interestingly, the following process gives different results:

Open up a new scene.
Add a subdivision surface modifier to the default cube.
Set it to 'Simple' mode and the number of subdivisions to 1.
Apply the modifier.
Repeat steps 2-4 four more times.
Run the intersection check in 3D Print Toolbox.

For me, this gives a result of 0 intersections, despite the second cube being seemingly identical to the first.

I'm noticing similar behavior on other flat geometric shapes, though less so on more organic geometry. Not sure if that helps at all.

Using Blender 2.90.1 on Windows 10 I would just like to add this odd behavior I've noticed With the 3D Print Toolbox intersection check which seems related to this problem: 1. Open up a new scene. 2. Add a subdivision surface modifier to the default cube. 3. Set it to 'Simple' mode and the number of subdivisions to 5. 4. Apply the modifier. 5. Run the intersection check in 3D Print Toolbox. This gives me a result of 112 intersections, despite this being a simple flat cube. The intersections seem to be random faces on the sides of the cube. ![3DPrintToolboxIssue01.jpg](https://archive.blender.org/developer/F8973722/3DPrintToolboxIssue01.jpg) Interestingly, the following process gives different results: 1. Open up a new scene. 2. Add a subdivision surface modifier to the default cube. 3. Set it to 'Simple' mode and the number of subdivisions to 1. 4. Apply the modifier. 5. Repeat steps 2-4 four more times. 6. Run the intersection check in 3D Print Toolbox. For me, this gives a result of 0 intersections, despite the second cube being seemingly identical to the first. ![3DPrintToolboxIssue02.jpg](https://archive.blender.org/developer/F8973726/3DPrintToolboxIssue02.jpg) I'm noticing similar behavior on other flat geometric shapes, though less so on more organic geometry. Not sure if that helps at all.

Mo Broots commented

2020-11-24 06:09:38 +01:00

Added subscriber: @shmuper

Mo Broots commented

2020-11-24 06:09:38 +01:00

Hi!,

Using 2.90.1

This is not a 3D print tool issue, this really seems to be on a geometry level. When exporting and loading up these models in the Dremmel slicer the normals are all broken and I cannot print anything.

I am working on two very very low polygon models and although I managed to fix all the issues on the thin model, it still doesn't work when I export it as an .stl to bring in my 3D slicer.

On the bigger model, I cannot get rid of the final intersect face. I got rid of all the intersect faces by recreating single faces pressing F. And that after deleting floating, merging vertex by distance, recreating normals etc...

I will try going back to 2.80 but dang 2.9 is delicious. Keep up the good work!

Mo

Hi!, Using 2.90.1 This is not a 3D print tool issue, this really seems to be on a geometry level. When exporting and loading up these models in the Dremmel slicer the normals are all broken and I cannot print anything. I am working on two very very low polygon models and although I managed to fix all the issues on the thin model, it still doesn't work when I export it as an .stl to bring in my 3D slicer. On the bigger model, I cannot get rid of the final intersect face. I got rid of all the intersect faces by recreating single faces pressing F. And that after deleting floating, merging vertex by distance, recreating normals etc... I will try going back to 2.80 but dang 2.9 is delicious. Keep up the good work! Mo ![blender_intersect_face.JPG](https://archive.blender.org/developer/F9363404/blender_intersect_face.JPG) ![dremmel_slicer_normals.JPG](https://archive.blender.org/developer/F9363403/dremmel_slicer_normals.JPG)

Germano Cavalcante commented

2020-11-24 14:17:39 +01:00

Added subscribers: @ideasman42, @mano-wii

Germano Cavalcante commented

2020-11-24 14:17:39 +01:00

I'm not sure but it is possible that this problem is due to recent changes that I made to the function isect_tri_tri_v3 (however mesh analysis does not show any intersection).
@ideasman42, if confirmed that the problem is that function, I will be willing to fix it.

I'm not sure but it is possible that this problem is due to recent changes that I made to the function `isect_tri_tri_v3` (however mesh analysis does not show any intersection). @ideasman42, if confirmed that the problem is that function, I will be willing to fix it.

Mo Broots commented

2020-11-25 07:37:30 +01:00

I used the following functions on the meshes if that can help:

Loop cut
extrude region
Fill

indeed 2.80 gave me similar issues with the meshes, will go back to 2.79 as suggested above.

I used the following functions on the meshes if that can help: - Loop cut - extrude region - Fill indeed 2.80 gave me similar issues with the meshes, will go back to 2.79 as suggested above.

Mo Broots commented

2020-11-27 03:38:53 +01:00

It looks like it's fixed in 2.91 ! Cudos, thank you!!!