Editing mesh.vertices.co in frame_change_pre handler and export mesh as alembic causes random crash and results in a static mesh #74339

New Issue

songwiki · 2020-03-01T18:06:00+01:00

songwiki commented

2020-03-01 18:06:00 +01:00

System Information
Operating system: Windows 10.0.18363.657
Graphics card: GeForce RTX 2080

Blender Version
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: 77d23b0bd7, type: Release
build date: 2020-02-13, 01:56:46

Short description of error
I made an addon that reads obj file per frame and changes an object.data.vertices- [x].co by a for loop.
blender plays well in viewport
but when i try to export an alembic. it outputs a static mesh.and sometimes blender goes crash

Exact steps for others to reproduce the error
full addon is in the zip
T74339_edit.blend

Run this script and click play(changes timeline). The monkey should be deformed.

Then export the alembic. Import it back, it is static.

@persistent
def frame_step(scene):
    depsgraph = bpy.context.evaluated_depsgraph_get()
    try:
        for obj in bpy.data.objects:
            if obj.objseq_settings.loaded:
                with SimpleWaveFront(obj.objseq_settings, scene.frame_current) as vertices:
                    for i in range(min(len(obj.data.vertices), len(vertices))):
                        obj.data.vertices[i].co = vertices[i]
                    obj.data = obj.data
                obj = obj.evaluated_get(depsgraph)
    except Exception as e:
        raise e

demo.zip

**System Information** Operating system: Windows 10.0.18363.657 Graphics card: GeForce RTX 2080 **Blender Version** Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: 77d23b0bd76f, type: Release build date: 2020-02-13, 01:56:46 **Short description of error** I made an addon that reads obj file per frame and changes an object.data.vertices- [x].co by a for loop. blender plays well in viewport but when i try to export an alembic. it outputs a static mesh.and sometimes blender goes crash **Exact steps for others to reproduce the error** *full addon is in the zip* [T74339_edit.blend](https://archive.blender.org/developer/F8421780/T74339_edit.blend) Run this script and click play(changes timeline). The monkey should be deformed. ![GIF.gif](https://archive.blender.org/developer/F8421787/GIF.gif) Then export the alembic. Import it back, it is static. ``` @persistent def frame_step(scene): depsgraph = bpy.context.evaluated_depsgraph_get() try: for obj in bpy.data.objects: if obj.objseq_settings.loaded: with SimpleWaveFront(obj.objseq_settings, scene.frame_current) as vertices: for i in range(min(len(obj.data.vertices), len(vertices))): obj.data.vertices[i].co = vertices[i] obj.data = obj.data obj = obj.evaluated_get(depsgraph) except Exception as e: raise e ``` [demo.zip](https://archive.blender.org/developer/F8381805/demo.zip)

songwiki commented

2020-03-01 18:06:00 +01:00

Added subscriber: @MoePus

Ankit Meel commented

2020-03-19 17:52:40 +01:00

Added subscriber: @ankitm

Ankit Meel commented

2020-03-19 17:52:40 +01:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Ankit Meel commented

2020-03-19 17:52:40 +01:00

Not sure Bug tracker would be a good place to debug an Addon. Can the bug be redone with simpler steps ?

songwiki commented

2020-03-22 07:07:31 +01:00

In #74339#894618, @ankitm wrote:
Not sure Bug tracker would be a good place to debug an Addon. Can the bug be redone with simpler steps ?

Yes. A simple setup is:

Add a monkey in the scene and name it Suzanne
Run the following code in console

import bpy
from mathutils import Vector
def frame_step(scene):
    depsgraph = bpy.context.evaluated_depsgraph_get()
    try:
        for obj in bpy.data.objects:
            if obj.name == "Suzanne":
                for i in range(len(obj.data.vertices)):
                    co = obj.data.vertices[i].co
                    obj.data.vertices[i].co = Vector((co.x * 1.01, co.y * 1.01, co.z))
                obj.data = obj.data
                obj = obj.evaluated_get(depsgraph)
    except Exception as e:
        raise e

bpy.app.handlers.frame_change_pre.append(frame_step)

Export Alembic
Blender will either crash or export a static alembic.

> In #74339#894618, @ankitm wrote: > Not sure Bug tracker would be a good place to debug an Addon. Can the bug be redone with simpler steps ? Yes. A simple setup is: 1. Add a monkey in the scene and name it Suzanne 2. Run the following code in console ``` import bpy from mathutils import Vector def frame_step(scene): depsgraph = bpy.context.evaluated_depsgraph_get() try: for obj in bpy.data.objects: if obj.name == "Suzanne": for i in range(len(obj.data.vertices)): co = obj.data.vertices[i].co obj.data.vertices[i].co = Vector((co.x * 1.01, co.y * 1.01, co.z)) obj.data = obj.data obj = obj.evaluated_get(depsgraph) except Exception as e: raise e bpy.app.handlers.frame_change_pre.append(frame_step) ``` 3. Export Alembic 4. Blender will either crash or export a static alembic.

Ankit Meel commented

2020-03-22 07:25:28 +01:00

Cannot redo. you find it static because there was no movement on the money before exporting?
I did the same steps, with some keyframes and here's the alembic and the blend file #74339.abc

#74339.blend

Cannot redo. you find it static because there was no movement on the money before exporting? I did the same steps, with some keyframes and here's the alembic and the blend file [#74339.abc](https://archive.blender.org/developer/F8421763/T74339.abc) [#74339.blend](https://archive.blender.org/developer/F8421766/T74339.blend)

songwiki commented

2020-03-22 07:36:05 +01:00

T74339_edit.blend

Run this script and click play(changes timeline). The monkey should be deformed.

Then export the alembic.

[T74339_edit.blend](https://archive.blender.org/developer/F8421780/T74339_edit.blend) Run this script and click play(changes timeline). The monkey should be deformed. ![GIF.gif](https://archive.blender.org/developer/F8421787/GIF.gif) Then export the alembic.

Ankit Meel commented

2020-03-22 07:43:33 +01:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Ankit Meel commented

2020-03-22 07:43:33 +01:00

Oh yeah. there's a static mesh.
as a workaround, https://docs.blender.org/api/current/bpy.types.bpy_struct.html#bpy.types.bpy_struct.keyframe_insert

Oh yeah. there's a static mesh. as a workaround, https://docs.blender.org/api/current/bpy.types.bpy_struct.html#bpy.types.bpy_struct.keyframe_insert

Germano Cavalcante commented

2020-05-05 15:13:18 +02:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2020-05-05 15:13:18 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Germano Cavalcante commented

2020-05-05 15:13:18 +02:00

I can't reproduce the crash you can try the latest daily build: https://builder.blender.org/download/
I'm also not sure if the fact that alembic doesn't create an animated mesh with this script is a bug.
I suggest you ask on support sites: https://www.blender.org/support/

I can't reproduce the crash you can try the latest daily build: https://builder.blender.org/download/ I'm also not sure if the fact that alembic doesn't create an animated mesh with this script is a bug. I suggest you ask on support sites: https://www.blender.org/support/

songwiki commented

2020-05-12 14:59:39 +02:00

In #74339#924732, @mano-wii wrote:
I can't reproduce the crash you can try the latest daily build: https://builder.blender.org/download/
I'm also not sure if the fact that alembic doesn't create an animated mesh with this script is a bug.
I suggest you ask on support sites: https://www.blender.org/support/

Use T74339_edit.blend and add a Subdivision Modifier then apply.
Finally export alembic, Blender may crash.

Crash Log on 2.90-542ff416e274

https://developer.blender.org/P1386

> In #74339#924732, @mano-wii wrote: > I can't reproduce the crash you can try the latest daily build: https://builder.blender.org/download/ > I'm also not sure if the fact that alembic doesn't create an animated mesh with this script is a bug. > I suggest you ask on support sites: https://www.blender.org/support/ Use T74339_edit.blend and add a Subdivision Modifier then apply. Finally export alembic, Blender may crash. Crash Log on 2.90-542ff416e274 https://developer.blender.org/P1386

Ankit Meel commented

2020-05-12 17:08:18 +02:00

Could you please edit that comment and replace the log with https://developer.blender.org/P1386 ?

Ankit Meel commented

2020-05-12 18:22:19 +02:00

Changed status from 'Needs User Info' to: 'Needs Triage'

Ankit Meel commented

2020-05-12 18:22:19 +02:00

it does crash, around frame 42.
Not confirming because of the script.

it does crash, around frame 42. Not confirming because of the script.

Richard Antalik commented

2020-06-16 18:39:37 +02:00

Added subscriber: @iss

Richard Antalik commented

2020-06-16 18:39:37 +02:00

Changed status from 'Needs Triage' to: 'Needs User Info'

Richard Antalik commented

2020-06-16 18:39:37 +02:00

I can not reproduce any crash here as well (using 2.90 build). Can not check 542ff416e274 to see if this has been resolved. Can you check again with latest 2.90 build?

The fact, that exported mesh is static is likely correct, since alembic exporter uses own dependency graph.

I can not reproduce any crash here as well (using 2.90 build). Can not check `542ff416e274` to see if this has been resolved. Can you check again with latest 2.90 build? The fact, that exported mesh is static is likely correct, since alembic exporter uses own dependency graph.

songwiki commented

2020-06-21 12:44:02 +02:00

In #74339#955112, @iss wrote:
I can not reproduce any crash here as well (using 2.90 build). Can not check 542ff416e274 to see if this has been resolved. Can you check again with latest 2.90 build?

The fact, that exported mesh is static is likely correct, since alembic exporter uses own dependency graph.

Thank you.
It does not crash in the lastest 2.90 build.
And is there any plan to support export abc of a python api modified mesh? (though i dont need it now)

> In #74339#955112, @iss wrote: > I can not reproduce any crash here as well (using 2.90 build). Can not check `542ff416e274` to see if this has been resolved. Can you check again with latest 2.90 build? > > The fact, that exported mesh is static is likely correct, since alembic exporter uses own dependency graph. Thank you. It does not crash in the lastest 2.90 build. And is there any plan to support export abc of a python api modified mesh? (though i dont need it now)

Richard Antalik commented

2020-06-22 04:31:44 +02:00

Changed status from 'Needs User Info' to: 'Archived'

Richard Antalik closed this issue

2020-06-22 04:31:44 +02:00

Richard Antalik self-assigned this 2020-06-22 04:31:44 +02:00

Richard Antalik commented

2020-06-22 04:31:44 +02:00

Not sure about abc exporter, but AFAIK feature to access render depsgraph(which is also separate) would be nice to have, but I am not aware of any concrete plans.

If there is no crash I will close this report as there is no bug. Thanks for reporting anyway.

Not sure about abc exporter, but AFAIK feature to access render depsgraph(which is also separate) would be nice to have, but I am not aware of any concrete plans. If there is no crash I will close this report as there is no bug. Thanks for reporting anyway.

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Editing mesh.vertices.co in frame_change_pre handler and export mesh as alembic causes random crash and results in a static mesh #74339