Cloth simulation, Rest Shape Key does not function / Dynamic Mesh always on #115321

New Issue

William-de-Grasse · 2023-11-24T00:34:05+01:00

William-de-Grasse commented

2023-11-24 00:34:05 +01:00

System Information
Operating system: Windows 10
Graphics card: RTX 4090

Blender Version
Broken: 3.6.1, 4.0.1
Worked: 3.4.1 (have not tried others)

Short description of error
For a cloth simulation on an object with shape keys, the Rest Shape Key field does not work, or it works if the project was already using that setting and no modifiers have changed. Changing the rest shape key at any point will cause it to break and use dynamic mesh only.

Interestingly enough, adding a Subdiv modifier before the cloth simulation will prevent this issue.

#40053 looks like a similar error, probably coincidental.

Exact steps for others to reproduce the error
Using the attached cloth.blend, change the Rest Shape Key and simulate. After that, any changes to the shape keys in the object data panel will cause the rest shape to change.

**System Information** Operating system: Windows 10 Graphics card: RTX 4090 **Blender Version** Broken: 3.6.1, 4.0.1 Worked: 3.4.1 (have not tried others) **Short description of error** For a cloth simulation on an object with shape keys, the Rest Shape Key field does not work, or it works if the project was already using that setting and no modifiers have changed. Changing the rest shape key at any point will cause it to break and use dynamic mesh only. Interestingly enough, adding a Subdiv modifier before the cloth simulation will prevent this issue. #40053 looks like a similar error, probably coincidental. **Exact steps for others to reproduce the error** Using the attached cloth.blend, change the Rest Shape Key and simulate. After that, any changes to the shape keys in the object data panel will cause the rest shape to change.

cloth.blend

810 KiB

William-de-Grasse added the

labels 2023-11-24 00:34:06 +01:00

Richard Antalik added

and removed

labels 2023-11-24 05:21:10 +01:00

Jose Conseco commented

2024-02-12 21:39:02 +01:00

Below I attached, IMO easier, setup, where we have 'Rest' shapekey - square mesh, and 'stretched' shapekey - elongated on x axis.
Expected result:

Cloth sim should relax mesh - to its squarish rest shape (and uniform edge lengths).
Actual result:
mesh stays elongated, when simulated. Uniform edges lengths, from 'Rest' shape gets ignored.

I know it works in Blender 3.3 (make sure to reset cloth sim cache properly) .

Below I attached, IMO easier, setup, where we have 'Rest' shapekey - square mesh, and 'stretched' shapekey - elongated on x axis. Expected result: 1. Cloth sim should relax mesh - to its squarish rest shape (and uniform edge lengths). Actual result: 2. mesh stays elongated, when simulated. Uniform edges lengths, from 'Rest' shape gets ignored. I know it works in Blender 3.3 (make sure to reset cloth sim cache properly) .

cloth_rest_shape_not_working.blend

240 KiB

Pavel-Linnikov commented

2024-02-18 15:57:40 +01:00

Can confirm Jose Conseco
Comparison done on 3.3.15 and 3.6.8 versions.
Decided to include a short window-to-window video of the simulation with the same basic conditions for both simulations as it seems to me that it describes the issue better

Can confirm Jose Conseco Comparison done on 3.3.15 and 3.6.8 versions. Decided to include a short window-to-window video of the simulation with the same basic conditions for both simulations as it seems to me that it describes the issue better

2024-02-18 17-51-19.mp4

6.4 MiB

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Cloth simulation, Rest Shape Key does not function / Dynamic Mesh always on #115321