Adding vertices when Basis Shapekey is active prevents changes to the Basis from affecting other keys #96681

Open
opened 2022-03-21 17:49:11 +01:00 by Adam Janz · 10 comments

System Information
Operating system: Windows-8.1-6.3.9600-SP0 64 Bits
Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.89

Blender Version
Broken: version: 3.1.0, branch: master, commit date: 2022-03-08 18:16, hash: c77597cd0e
Worked: (Unknown, bug exists at least as far back as 2.79b)

Short description of error
As requested by @ideasman42, this is a report of the following shapekey bug:

When vertices are added to a mesh with shapekeys when the Basis Shapekey is selected, any changes made to the Basis key will NOT propagate to other keys.

HOWEVER, if vertices are added when any key OTHER than the Basis is selected (ie. Key1), and then the Basis key is edited, any changes to the Basis WILL correctly propagate to other keys.

ADDITIONALLY, if vertices are added when the Basis Shapekey is selected, BUT Edit mode is first EXITED then RE-ENTERED before any vertex manipulation is made to the Basis key, then any changes to the Basis WILL correctly propagate to other keys.

Exact steps for others to reproduce the error
All three scenarios below (based on a new empty project) are demonstrated in this example video HERE .

1. Add a cube, add 2 shapekeys. With the "Basis" key selected, enter Edit mode and add loop cuts. Move the vertices. Select "Key1" and notice the changes to the "Basis" key have NOT affected Key1. This is the only scenario where the bug exists.

2. Add a cube, add 2 shapekeys. With the "Key1" key selected, enter Edit mode and add loop cuts. Now select the "Basis" key. Move the vertices. Select "Key1" again and notice the changes to the Basis key have affected Key1 as expected. This is one workaround.

3. Add a cube, add 2 shapekeys. With the "Basis" key selected, enter Edit mode and add loop cuts. Now EXIT Edit mode and RE-ENTER. Move the vertices. Select "Key1" and notice the changes to the Basis key have affected Key1 as expected. This is a second workaround.

P.S. Apologies for the very late report. The last 3 weeks have been heavily pre-occupied with music production. And I'm super thrilled that #44415 made it into the 3.1 release. Thanks so much to @ideasman42 and all the talented Blender devs for making this happen! :-)

**System Information** Operating system: Windows-8.1-6.3.9600-SP0 64 Bits Graphics card: GeForce GTX 970/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 460.89 **Blender Version** Broken: version: 3.1.0, branch: master, commit date: 2022-03-08 18:16, hash: `c77597cd0e` Worked: (Unknown, bug exists at least as far back as 2.79b) **Short description of error** As requested by @ideasman42, this is a report of the following shapekey bug: When vertices are added to a mesh with shapekeys when the **Basis Shapekey is selected**, any changes made to the Basis key will **NOT** propagate to other keys. HOWEVER, if vertices are added when any key **OTHER** than the Basis is selected (ie. Key1), and then the Basis key is edited, any changes to the Basis **WILL** correctly propagate to other keys. ADDITIONALLY, if vertices are added when the Basis Shapekey is selected, **BUT** Edit mode is first **EXITED** then **RE-ENTERED** before any vertex manipulation is made to the Basis key, then any changes to the Basis **WILL** correctly propagate to other keys. **Exact steps for others to reproduce the error** All three scenarios below (based on a new empty project) are demonstrated in **[this example video HERE ](https://youtu.be/v7YUb_9H2Ec)**. **1.** Add a cube, add 2 shapekeys. With the "Basis" key selected, enter Edit mode and add loop cuts. Move the vertices. Select "Key1" and notice the changes to the "Basis" key have **NOT** affected Key1. **This is the only scenario where the bug exists.** **2.** Add a cube, add 2 shapekeys. With the "Key1" key selected, enter Edit mode and add loop cuts. Now select the "Basis" key. Move the vertices. Select "Key1" again and notice the changes to the Basis key have affected Key1 as expected. **This is one workaround.** **3.** Add a cube, add 2 shapekeys. With the "Basis" key selected, enter Edit mode and add loop cuts. Now **EXIT** Edit mode and **RE-ENTER**. Move the vertices. Select "Key1" and notice the changes to the Basis key have affected Key1 as expected. **This is a second workaround.** *P.S. Apologies for the very late report. The last 3 weeks have been heavily pre-occupied with music production. And I'm super thrilled that #44415 made it into the 3.1 release. Thanks so much to @ideasman42 and all the talented Blender devs for making this happen!* :-)
Author

Added subscribers: @ideasman42, @AdamJanz

Added subscribers: @ideasman42, @AdamJanz

#103427 was marked as duplicate of this issue

#103427 was marked as duplicate of this issue

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

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

Added subscriber: @mano-wii

Added subscriber: @mano-wii

Added subscriber: @Art4D

Added subscriber: @Art4D

Will it take us another 7 years to fix this critical bug?

Blender still breaks shapekeys if new vertices are added to Basic.
#44415 is only half fixed. The fix doesn't work if new vertices are added to Basic.

Will it take us another 7 years to fix this critical bug? Blender still breaks shapekeys if new vertices are added to Basic. #44415 is only half fixed. The fix doesn't work if new vertices are added to Basic.
Member

Added subscribers: @qwezxcaa, @lichtwerk, @PratikPB2123

Added subscribers: @qwezxcaa, @lichtwerk, @PratikPB2123
Philipp Oeser removed the
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label 2023-02-09 15:27:56 +01:00

And so, two more years have passed, and this critical bug from nine years ago is still not fixed.

Due to this bug, I can't add a new mesh to my finished character with shape keys and rig. Because at some random moment, the blender just breaks all the shape keys of the character. The blender just destroys all my work done with the new mesh because the old shape keys stop working correctly at some point.

And so, two more years have passed, and this critical bug from nine years ago is still not fixed. Due to this bug, I can't add a new mesh to my finished character with shape keys and rig. Because at some random moment, the blender just breaks all the shape keys of the character. The blender just destroys all my work done with the new mesh because the old shape keys stop working correctly at some point.
Author

@Art4D Yes, that definitely can be very frustrating when changes made to the mesh don't get transferred to the other keys. At the moment, the best workaround is to add any new loop cuts and extrusions to the Base Key but do NOT move the new vertices or faces (ie. if extruding, right-click to cancel so the new faces will stay in place). Then EXIT Edit Mode and re-enter Edit Mode. Now you can move your vertices and faces as you wish and the new positions will correctly propagate to the other shapekeys.

Of course, it's very easy to forget to to do this. And using "Vertex" > "Propagate to shapes" is not a viable solution in most cases, because the new vertex positions in the Base Key will OVERRIDE the other keys' existing vertex positions instead of blending with them.

So unfortunately, it's VERY crucial to follow the workaround mentioned until a much-needed fix is implemented, otherwise hours of work can be permanently lost.

@Art4D Yes, that definitely can be very frustrating when changes made to the mesh don't get transferred to the other keys. At the moment, the best workaround is to add any new loop cuts and extrusions to the Base Key but **do NOT move** the new vertices or faces (ie. if extruding, right-click to cancel so the new faces will stay in place). Then **EXIT** Edit Mode and **re-enter** Edit Mode. Now you can move your vertices and faces as you wish and the new positions will correctly propagate to the other shapekeys. Of course, it's very easy to forget to to do this. And using "Vertex" > "Propagate to shapes" is not a viable solution in most cases, because the new vertex positions in the Base Key will **OVERRIDE** the other keys' existing vertex positions instead of blending with them. So unfortunately, it's **VERY crucial** to follow the workaround mentioned until a much-needed fix is implemented, otherwise hours of work can be permanently lost.
Author

Hopefully Campbell Barton @ideasman42 can shed some light on whether this bug can be addressed. It is currently not assigned to anyone.

Hopefully Campbell Barton @ideasman42 can shed some light on whether this bug can be addressed. It is currently not assigned to anyone.
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Reference: blender/blender#96681
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