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Maniphest T88059

Mesh converted from a curve gets weirdly mirrored
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Description

System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71

Blender Version
Broken: version: 3.0.0 Alpha, branch: master, commit date: 2021-05-03 23:07, hash: rBe6bf272abd92
Worked: (newest version of Blender that worked as expected)

Exact steps for others to reproduce the error

bug.blend852 KBDownload

Change operation on Attr. Vector Math from Add to Substract, mesh gets mirrored in all axes like this,

Event Timeline

Miro Horváth (dreamak) created this task.May 5 2021, 4:37 PM
Miro Horváth (dreamak) added a project: Geometry Nodes.
Philipp Oeser (lichtwerk) changed the task status from Needs Triage to Confirmed.May 6 2021, 2:08 PM
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).

Can confirm.

Philipp Oeser (lichtwerk) added a project: Nodes & Physics.May 6 2021, 2:09 PM
Hans Goudey (HooglyBoogly) changed the task status from Confirmed to Needs Information from User.May 6 2021, 4:16 PM
Hans Goudey (HooglyBoogly) added a subscriber: Hans Goudey (HooglyBoogly).

Could you explain what the expected result would be? As far as I can tell, the attribute vector math node simply negates all of the position values, which is equivalent to scaling by -1 on every axis.

Miro Horváth (dreamak) added a comment.May 6 2021, 4:27 PM

@Hans Goudey (HooglyBoogly) what I see as a bugy behaviour is that it does something to geometry even though I substract nothing( Vector(0,0,0) ) from position attribute. So to answer your question I'd expect the same state of geometry as when operation is Add.

Philipp Oeser (lichtwerk) changed the task status from Needs Information from User to Confirmed.May 6 2021, 4:33 PM

@Hans Goudey (HooglyBoogly) : I would also expect to have the same output if a zero vector is subtracted, no?

Hans Goudey (HooglyBoogly) added a comment.May 6 2021, 4:40 PM

Right, but the node does A - B, so this is position = 0 - position,

Miro Horváth (dreamak) added a comment.May 6 2021, 4:47 PM

Oh, wrong order of operations... apologies, my bad!

Philipp Oeser (lichtwerk) closed this task as Archived.May 6 2021, 4:56 PM

Doh! on my side as well :)

Guess we can close then...