Basis shapekey editing while rendering bug #50524

New Issue

Jaroslav Novotny · 2017-01-25T12:28:14+01:00

Jaroslav Novotny commented

2017-01-25 12:28:14 +01:00

System Information
Win 7 64bit GTX 980Ti

Blender Version
Broken: 2.78a (e8299c8)

Short description of error
When the basis shapekey is edited, all other shapekeys reflect the change, this is ok.
When there is a 3D view in render shading mode and a basis is edited, shapekeys no longer reflect the the basis change.

Exact steps for others to reproduce the error
See the cube in the scene with a shapekey.
Edit the Basis key of the cube (for example turn the cube into sphere Shift+Alt+S).
See the other shapekey working relatively to the new basis.

Open the file again and switch the right upper 3D window into rendered mode (doesn't matter if CPU or GPU).
Change the Basis key the same way.
The other shapekey no longer reflects the change of the basis.

shapekey_bug.blend

**System Information** Win 7 64bit GTX 980Ti **Blender Version** Broken: 2.78a (e8299c8) **Short description of error** When the basis shapekey is edited, all other shapekeys reflect the change, this is ok. When there is a 3D view in render shading mode and a basis is edited, shapekeys no longer reflect the the basis change. **Exact steps for others to reproduce the error** See the cube in the scene with a shapekey. Edit the Basis key of the cube (for example turn the cube into sphere Shift+Alt+S). See the other shapekey working relatively to the new basis. Open the file again and switch the right upper 3D window into rendered mode (doesn't matter if CPU or GPU). Change the Basis key the same way. The other shapekey no longer reflects the change of the basis. [shapekey_bug.blend](https://archive.blender.org/developer/F439898/shapekey_bug.blend)

Jaroslav Novotny commented

2017-01-25 12:28:14 +01:00

Changed status to: 'Open'

Jaroslav Novotny commented

2017-01-25 12:28:14 +01:00

Added subscriber: @jerryno

Aaron Carlisle commented

2017-02-02 05:20:59 +01:00

Added subscriber: @Blendify

Aaron Carlisle commented

2017-02-02 05:20:59 +01:00

Changed status from 'Open' to: 'Resolved'

Aaron Carlisle closed this issue

2017-02-02 05:20:59 +01:00

Bastien Montagne was assigned by Aaron Carlisle

2017-02-02 05:20:59 +01:00

Aaron Carlisle commented

2017-02-02 05:20:59 +01:00

I can confirm that something is weird here. Assigning to #mont29 for now.

Aaron Carlisle commented

2017-02-02 05:21:20 +01:00

Changed status from 'Resolved' to: 'Open'

Aaron Carlisle reopened this issue

2017-02-02 05:21:20 +01:00

Bastien Montagne commented

2017-02-02 10:43:33 +01:00

Can confirm the problem too… Thing is, shape keys are full of design issues, and iirc there are several ways to break the sync to the basis… just wasn’t aware of that one :(

Will try to have a lok again here, but last time I checked this was an unsolvable nightmare.

Can confirm the problem too… Thing is, shape keys are full of design issues, and iirc there are several ways to break the sync to the basis… just wasn’t aware of that one :( Will try to have a lok again here, but last time I checked this was an unsolvable nightmare.

Bastien Montagne removed their assignment 2017-02-02 12:51:44 +01:00

Bastien Montagne commented

2017-02-02 12:51:44 +01:00

Added subscribers: @Sergey, @mont29

Bastien Montagne commented

2017-02-02 12:51:44 +01:00

Problem is with prepare_mesh_for_viewport_render() in scene.c, which calls BM_mesh_bm_to_me().

That conversion from BMesh to Mesh does a very tricky handling of shape keys, to correctly propagate basis editing to 'children' shapekeys.

Issue is that for rendered viewport, this BMesh-to-Mesh conversion gets called repeatedly, but without calling Mesh-to-BMesh in-between, so diff data stored in BMesh to handle shapekeys become useless.

Unless @Sergey has nice idea to fix this, I’m tempted to consider this as known failure for now, especially since in Blender 2.8 we intend to make BMesh directly usable by render engines (and hence, that super-ugly conversion would not be needed anymore anyway here).

Problem is with `prepare_mesh_for_viewport_render()` in `scene.c`, which calls `BM_mesh_bm_to_me()`. That conversion from BMesh to Mesh does a very tricky handling of shape keys, to correctly propagate basis editing to 'children' shapekeys. Issue is that for rendered viewport, this BMesh-to-Mesh conversion gets called repeatedly, but without calling Mesh-to-BMesh in-between, so diff data stored in BMesh to handle shapekeys become useless. Unless @Sergey has nice idea to fix this, I’m tempted to consider this as known failure for now, especially since in Blender 2.8 we intend to make BMesh directly usable by render engines (and hence, that super-ugly conversion would not be needed anymore anyway here).

blender-admin commented

2017-02-02 17:00:52 +01:00

This issue was referenced by 9e2dca933e

This issue was referenced by 9e2dca933e3e1541c5d40a89e10a0277be94e2fe

Bastien Montagne commented

2017-02-02 17:06:12 +01:00

Changed status from 'Open' to: 'Resolved'

Bastien Montagne closed this issue

2017-02-02 17:06:12 +01:00

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Basis shapekey editing while rendering bug #50524