Hair wrong position on geometry surface when applying all shape keys #100756

New Issue

JayB · 2022-09-01T18:55:14+02:00

JayB commented

2022-09-01 18:55:14 +02:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 516.59

Blender Version
Broken: version: 3.3.0 Release Candidate, branch: master, commit date: 2022-08-31 16:43, hash: cdc0be48c9

Short description of error
When applying all the shape keys on a mesh which has hair attached to it, the hair position default back to the mesh shape prior any shape keys.
If the shape keys is not applied, the hair in the viewport and when viewport rendering is at the correct position.

Exact steps for others to reproduce the error
Open the .blend attached.
select the sphere and in the Object Data Properties tab, in the Shape Keys section, click on the arrow and click on Apply all shape keys. The hair will not follow the geometry anymore.

And the steps I took to create the simple demo scene :

Create a UV sphere
While the sphere is selected, Shift + A > Curve > Empty Hair
Edit mode while hair selected, add hair on the surface of the UV shpere.
Select the UV sphere. Creating a basis shape key
Creating a shape key with geometry changes
Apply all shape keys.

error_apply_blendshape_with_hair.blend

I hope this can help you narrow down what could be the issue and thank you for your help !

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 516.59 **Blender Version** Broken: version: 3.3.0 Release Candidate, branch: master, commit date: 2022-08-31 16:43, hash: `cdc0be48c9` **Short description of error** When applying all the shape keys on a mesh which has hair attached to it, the hair position default back to the mesh shape prior any shape keys. If the shape keys is not applied, the hair in the viewport and when viewport rendering is at the correct position. ![shapekeys_hair_issue_4.PNG](https://archive.blender.org/developer/F13447308/shapekeys_hair_issue_4.PNG) ![shapekeys_hair_issue_2.PNG](https://archive.blender.org/developer/F13447312/shapekeys_hair_issue_2.PNG) ![shapekeys_hair_issue_3.PNG](https://archive.blender.org/developer/F13447314/shapekeys_hair_issue_3.PNG) **Exact steps for others to reproduce the error** Open the .blend attached. select the sphere and in the Object Data Properties tab, in the Shape Keys section, click on the arrow and click on Apply all shape keys. The hair will not follow the geometry anymore. ![shapekeys_hair_issue.PNG](https://archive.blender.org/developer/F13447295/shapekeys_hair_issue.PNG) And the steps I took to create the simple demo scene : 1. Create a UV sphere 2. While the sphere is selected, Shift + A > Curve > Empty Hair 4. Edit mode while hair selected, add hair on the surface of the UV shpere. 5. Select the UV sphere. Creating a basis shape key 6. Creating a shape key with geometry changes 7. Apply all shape keys. [error_apply_blendshape_with_hair.blend](https://archive.blender.org/developer/F13447293/error_apply_blendshape_with_hair.blend) I hope this can help you narrow down what could be the issue and thank you for your help !

JayB commented

2022-09-01 18:55:14 +02:00

Added subscriber: @sinx

Germano Cavalcante commented

2022-09-01 20:58:02 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2022-09-01 20:58:02 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Germano Cavalcante commented

2022-09-01 20:58:02 +02:00

I can confirm the problem.
But this happens for any modifier or any edit in the Mesh.
I'm not sure what the behavior should be here and if this is really a bug.

I can confirm the problem. But this happens for any modifier or any edit in the Mesh. I'm not sure what the behavior should be here and if this is really a bug.

JayB commented

2022-09-01 21:04:23 +02:00

This comment was removed by @sinx

*This comment was removed by @sinx*

Iliya Katushenock commented

2022-09-01 21:14:33 +02:00

Added subscribers: @JacquesLucke, @mod_moder

Iliya Katushenock commented

2022-09-01 21:14:33 +02:00

@JacquesLucke
Could this be due to the fact that non-runtime data is used in this place?
node_geo_deform_curves_on_surface.cc$228

@JacquesLucke Could this be due to the fact that non-runtime data is used in this place? [node_geo_deform_curves_on_surface.cc$228 ](https://developer.blender.org/diffusion/B/browse/master/source/blender/nodes/geometry/nodes/node_geo_deform_curves_on_surface.cc$228)

Hans Goudey commented

2022-11-08 20:58:18 +01:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2022-11-08 20:58:18 +01:00

Changed status from 'Needs Developer To Reproduce' to: 'Archived'

Hans Goudey closed this issue

2022-11-08 20:58:18 +01:00

Hans Goudey commented

2022-11-08 20:58:18 +01:00

Applying shape keys changes the ground truth of the surface attachment, just like applying a modifier.
There are operators in curves sculpt mode to reattach curves to the surface when it changes. The proper one to use in this situation is "Snap to Deformed Surface".

Applying shape keys changes the ground truth of the surface attachment, just like applying a modifier. There are operators in curves sculpt mode to reattach curves to the surface when it changes. The proper one to use in this situation is "Snap to Deformed Surface".

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Hair wrong position on geometry surface when applying all shape keys #100756