Curves sculptmode: sculpting in deformed space breaks when using Duplicate Elements node (followed by Set Position) #101823

New Issue

Philipp Oeser · 2022-10-14T13:53:17+02:00

Philipp Oeser commented

2022-10-14 13:53:17 +02:00

System Information
Operating system: Linux-5.19.6-200.fc36.x86_64-x86_64-with-glibc2.35 64 Bits
Graphics card: NVIDIA GeForce RTX 3080 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 515.65.01

Blender Version
Broken: version: 3.4.0 Alpha, branch: master, commit date: 2022-10-10 00:22, hash: a24f11e0ec
Worked: -

Short description of error
Curves sculptmode: sculpting in deformed space breaks when using Duplicate Elements node (followed by Set Position)

Exact steps for others to reproduce the error
curves_sculptmode_duplicate_elements_crazyspace.blend

open .blend
try to comb in the "bad" area >> nothing happens
try to comb in the "good" area >> combing works

Probably needs something along the lines of 30113e54d2

**System Information** Operating system: Linux-5.19.6-200.fc36.x86_64-x86_64-with-glibc2.35 64 Bits Graphics card: NVIDIA GeForce RTX 3080 Laptop GPU/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 515.65.01 **Blender Version** Broken: version: 3.4.0 Alpha, branch: master, commit date: 2022-10-10 00:22, hash: `a24f11e0ec` Worked: - **Short description of error** Curves sculptmode: sculpting in deformed space breaks when using Duplicate Elements node (followed by Set Position) **Exact steps for others to reproduce the error** [curves_sculptmode_duplicate_elements_crazyspace.blend](https://archive.blender.org/developer/F13677442/curves_sculptmode_duplicate_elements_crazyspace.blend) - open .blend - try to comb in the "bad" area >> nothing happens - try to comb in the "good" area >> combing works Probably needs something along the lines of 30113e54d2

Philipp Oeser commented

2022-10-14 13:53:17 +02:00

Added subscriber: @lichtwerk

Philipp Oeser self-assigned this 2022-10-14 13:53:49 +02:00

Philipp Oeser commented

2022-10-14 13:53:49 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Hans Goudey commented

2022-10-14 18:36:23 +02:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2022-10-14 18:36:23 +02:00

I think this is a limitation of the way the deformed positions storage works. The first non-deforming node saves the positions, and they aren't adjusted after that. In general this is fundamental to the way it works-- any future node can't be evaluated on the saved curves edit data with the same results that it has on the curves.
The simple fix in this situation is to just swap the two nodes, that would make it faster anyway.

In the past we talked about letting node group makers set this data directly so they can have more control. That could help here

I think this is a limitation of the way the deformed positions storage works. The first non-deforming node saves the positions, and they aren't adjusted after that. In general this is fundamental to the way it works-- any future node can't be evaluated on the saved curves edit data with the same results that it has on the curves. The simple fix in this situation is to just swap the two nodes, that would make it faster anyway. In the past we talked about letting node group makers set this data directly so they can have more control. That could help here

Philipp Oeser commented

2022-10-15 15:21:00 +02:00

In #101823#1432536, @HooglyBoogly wrote:
The simple fix in this situation is to just swap the two nodes, that would make it faster anyway.

How would that work?
The Duplicate Elements needs to be before the Set Position (it uses the Duplicate Index as an input for Set Position)

Also just noticed that dropping a Deform Curves on Surface after a Duplicate Elements node will crash blender, will check/report that on Monday

> In #101823#1432536, @HooglyBoogly wrote: > The simple fix in this situation is to just swap the two nodes, that would make it faster anyway. How would that work? The `Duplicate Elements` needs to be before the `Set Position` (it uses the `Duplicate Index` as an input for `Set Position`) Also just noticed that dropping a `Deform Curves on Surface` after a `Duplicate Elements` node will crash blender, will check/report that on Monday

Hans Goudey commented

2022-10-15 22:06:02 +02:00

How would that work?

Ah, right, it doesn't. Sorry, didn't have the file open when I wrote that.

>How would that work? Ah, right, it doesn't. Sorry, didn't have the file open when I wrote that.

Jacques Lucke commented

2022-10-20 15:27:15 +02:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2022-10-20 15:27:15 +02:00

Changed status from 'Confirmed' to: 'Archived'

Jacques Lucke closed this issue

2022-10-20 15:27:15 +02:00

Jacques Lucke commented

2022-10-20 15:27:15 +02:00

This case is indeed not supported currently and might never be automatically. Blender doesn't really know how to interpret the positions set by the Set Position node and how they relate to original curves.

In this specific case one should first offset all curves and only then duplicate elements and add some randomness.

As Hans mentioned already, we could add nodes that allow the user to help Blender in such cases in the future.

This case is indeed not supported currently and might never be automatically. Blender doesn't really know how to interpret the positions set by the Set Position node and how they relate to original curves. In this specific case one should first offset all curves and only then duplicate elements and add some randomness. As Hans mentioned already, we could add nodes that allow the user to help Blender in such cases in the future.

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Curves sculptmode: sculpting in deformed space breaks when using Duplicate Elements node (followed by Set Position) #101823