Adding a mask modifier causes the shape key driver to fail. #74207

New Issue

Jun Takahashi · 2020-02-25T19:23:23+01:00

Jun Takahashi commented

2020-02-25 19:23:23 +01:00

System Information
Operating system:windows10(64bit)
Graphics card:GTX2060

Blender Version
Broken: ver 2.82 it is not daily build
Worked: (optional)

Short description of error

Exact steps for others to reproduce the error
1.Make two cube meshes.One is a source. One is a target.

2.Create an arbitrary shape key for each mesh.

3.Set the following data of the source mesh as the key driver of the target mesh.

data.shape_keys.key_blocks - [x] .value

4.Add a mask modifier to the source mesh and mask some vertices using vertex groups.

5.An error occurs when updating the driver.

blend file
Mask_Modifier_Bug.blend

video
Blender 2020-02-26 03-06-00.mp4

Problem can be avoided if this is driven by the mesh datablock instead of the object datablock.
Mask_Modifier_Bug_driven_by_mesh_datablock_instead_of_object_datablock.blend

**System Information** Operating system:windows10(64bit) Graphics card:GTX2060 **Blender Version** Broken: ver 2.82 it is not daily build Worked: (optional) **Short description of error** **Exact steps for others to reproduce the error** 1.Make two cube meshes.One is a source. One is a target. 2.Create an arbitrary shape key for each mesh. 3.Set the following data of the source mesh as the key driver of the target mesh. data.shape_keys.key_blocks - [x] .value 4.Add a mask modifier to the source mesh and mask some vertices using vertex groups. 5.An error occurs when updating the driver. blend file [Mask_Modifier_Bug.blend](https://archive.blender.org/developer/F8369796/Mask_Modifier_Bug.blend) video [Blender 2020-02-26 03-06-00.mp4](https://archive.blender.org/developer/F8369798/Blender_2020-02-26_03-06-00.mp4) Problem can be avoided if this is driven by the mesh datablock instead of the object datablock. [Mask_Modifier_Bug_driven_by_mesh_datablock_instead_of_object_datablock.blend](https://archive.blender.org/developer/F8372577/Mask_Modifier_Bug_driven_by_mesh_datablock_instead_of_object_datablock.blend)

Jun Takahashi commented

2020-02-25 19:23:24 +01:00

Added subscriber: @Jun-Takahashi

Philipp Oeser commented

2020-02-26 10:31:15 +01:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2020-02-26 10:31:15 +01:00

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

Philipp Oeser commented

2020-02-26 10:31:16 +01:00

Can confirm.

Problem can be avoided if this is driven by the mesh datablock instead of the object datablock.
Mask_Modifier_Bug_driven_by_mesh_datablock_instead_of_object_datablock.blend

Can confirm. Problem can be avoided if this is driven by the mesh datablock instead of the object datablock. [Mask_Modifier_Bug_driven_by_mesh_datablock_instead_of_object_datablock.blend](https://archive.blender.org/developer/F8372577/Mask_Modifier_Bug_driven_by_mesh_datablock_instead_of_object_datablock.blend)

Jacques Lucke commented

2020-02-26 15:01:37 +01:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2020-02-26 15:01:37 +01:00

This might be related: #65148.

Bastien Montagne commented

2020-02-26 18:40:14 +01:00

Added subscribers: @Sergey, @mont29

Bastien Montagne commented

2020-02-26 18:40:14 +01:00

The issue here is that the drivers gets evaluated by the depsgraph, using evaluated datablocks. And evaluated objects have evaluated obdata (like mesh) from modifier stack, which obviously have no shapekeys anymore (since those shapekey data would be completely invalid for the mesh generated by the modifiers most of the time).

Am not sure how to fix that best tbh, @Sergey might have ideas here?

Anyway, this is indeed a duplicate of #65148.

The issue here is that the drivers gets evaluated by the depsgraph, using evaluated datablocks. And evaluated objects have evaluated obdata (like mesh) from modifier stack, which obviously have no shapekeys anymore (since those shapekey data would be completely invalid for the mesh generated by the modifiers most of the time). Am not sure how to fix that best tbh, @Sergey might have ideas here? Anyway, this is indeed a duplicate of #65148.

Bastien Montagne commented

2020-02-26 18:40:29 +01:00

Closed as duplicate of #65148

Bastien Montagne closed this issue

2020-02-26 18:40:29 +01:00

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Adding a mask modifier causes the shape key driver to fail. #74207