Edge extrusion error MacOs #65654

New Issue

Eric Leo · 2019-06-09T09:41:39+02:00

Eric Leo commented

2019-06-09 09:41:39 +02:00

System Information
Operating system: Darwin-17.4.0-x86_64-i386-64bit 64 Bits
Graphics card: AMD Radeon RX 580 OpenGL Engine ATI Technologies Inc. 4.1 ATI-1.60.26

Blender Version
Broken: version: 2.80 (sub 74), branch: blender2.7, commit date: 2019-06-08 13:24, hash: 81b68f7279
Worked: (optional)

Short description of error
edge extrusion from a pane or a Ngon creates an extra face within extruded region.

Exact steps for others to reproduce the error
Add a plane, go to edit mode, go to edge select, select edges, extrude out.

Add circle fill type ngon. go to edit mode, select edges, extrude out.

Attached file has a circle Ngon filled and a plain ready for extrusion as well as an example of an extruded plane and circle. Also note that the problem does not occur when the fill type for a circle is set to triangle fan.

Edge extrusion error problem.blend

**System Information** Operating system: Darwin-17.4.0-x86_64-i386-64bit 64 Bits Graphics card: AMD Radeon RX 580 OpenGL Engine ATI Technologies Inc. 4.1 ATI-1.60.26 **Blender Version** Broken: version: 2.80 (sub 74), branch: blender2.7, commit date: 2019-06-08 13:24, hash: `81b68f7279` Worked: (optional) **Short description of error** edge extrusion from a pane or a Ngon creates an extra face within extruded region. **Exact steps for others to reproduce the error** Add a plane, go to edit mode, go to edge select, select edges, extrude out. Add circle fill type ngon. go to edit mode, select edges, extrude out. Attached file has a circle Ngon filled and a plain ready for extrusion as well as an example of an extruded plane and circle. Also note that the problem does not occur when the fill type for a circle is set to triangle fan. [Edge extrusion error problem.blend](https://archive.blender.org/developer/F7095989/Edge_extrusion_error_problem.blend)

Eric Leo commented

2019-06-09 09:41:39 +02:00

Added subscriber: @DiveMeCarzy

tom k commented

2019-06-09 12:34:57 +02:00

Added subscriber: @tomjk

tom k commented

2019-06-09 12:34:57 +02:00

This is because selecting all edges around a face also selects that face, so the face is also extruded.
You can get the behaviour you want by hitting Alt+E (or go to 3d view header -> Mesh menu -> Extrude submenu) and choosing Extrude Edges.

Screencast 2019-06-09 11:37:33.webm

Whether selecting all edges around a face in edge select mode should select the face is a question of design (and a good question too), but not a bug.

This is because selecting all edges around a face also selects that face, so the face is also extruded. You can get the behaviour you want by hitting Alt+E (or go to 3d view header -> Mesh menu -> Extrude submenu) and choosing Extrude Edges. [Screencast 2019-06-09 11:37:33.webm](https://archive.blender.org/developer/F7096120/Screencast_2019-06-09_11_37_33.webm) Whether selecting all edges around a face in edge select mode *should* select the face is a question of design (and a good question too), but not a bug.

Eric Leo commented

2019-06-09 18:53:31 +02:00

Yes I see what you mean, I had forgotten all about the extrude edge option. However, if I am extruding away from four selected lines, as in the case of a plain or multiple lines as in the case of an Ngon, why am I getting an extra face in between them. I should be getting a new face out ward from the direction of extrusion not a fill in between them as well. Also, why is this not happening if the original fill type of the circle is an triangle fan? In essence I am getting an extrusion and also filling a "new face" that I do not want. Does this happen in other design software? I only know blender, so I really have no idea if this is normal.

Sorry, but I think its a bug and not a feature. Maybe its just a really deep paper cut.

Yes I see what you mean, I had forgotten all about the extrude edge option. However, if I am extruding away from four selected lines, as in the case of a plain or multiple lines as in the case of an Ngon, why am I getting an extra face in between them. I should be getting a new face out ward from the direction of extrusion not a fill in between them as well. Also, why is this not happening if the original fill type of the circle is an triangle fan? In essence I am getting an extrusion and also filling a "new face" that I do not want. Does this happen in other design software? I only know blender, so I really have no idea if this is normal. Sorry, but I think its a bug and not a feature. Maybe its just a really deep paper cut.

tom k commented

2019-06-09 19:14:04 +02:00

Blender doesn't know how to differentiate between extruding perpendicular to the surface and extruding in the plane of the surface. If it did, and automatically toggled the extra fill face, it would potentially break workflow for those who extrude then transform in two seperate steps. Blender can't foresee your intent, so you have to let it know by choosing a particular extrusion mode.

The reason why you don't have this problems with triangle fans comes from the rule about how selecting all edges around a face also selects the face. When you select the outer edge of the tri-fan circle, you only have 1 out of 3 of the edges of any face selected, so they remain unselected.

I don't know about other software, sorry :)

Blender doesn't know how to differentiate between extruding perpendicular to the surface and extruding in the plane of the surface. If it did, and automatically toggled the extra fill face, it would potentially break workflow for those who extrude then transform in two seperate steps. Blender can't foresee your intent, so you have to let it know by choosing a particular extrusion mode. The reason why you don't have this problems with triangle fans comes from the rule about how selecting all edges around a face also selects the face. When you select the outer edge of the tri-fan circle, you only have 1 out of 3 of the edges of any face selected, so they remain unselected. ![trifanedges.png](https://archive.blender.org/developer/F7096471/trifanedges.png) I don't know about other software, sorry :)

Eric Leo commented

2019-06-09 19:18:06 +02:00

I see, that makes sense. Maybe then its not a bug? See what the judges say.
All, in all, you learn something new every day!

I see, that makes sense. Maybe then its not a bug? See what the judges say. All, in all, you learn something new every day!

Brecht Van Lommel commented

2019-06-09 21:49:39 +02:00

Added subscriber: @brecht