Export animated mesh to alembic fail when there are multiple UV maps #77021

New Issue

Lance Phan · 2020-05-24T12:51:55+02:00

Lance Phan commented

2020-05-24 12:51:55 +02:00

System Information
Operating system: Windows-10-10.0.17134-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 445.87

Blender Version
Broken: version: 2.83 (sub 17), branch: master, commit date: 2020-05-22 19:52, hash: e8dd8c2829
Worked: (newest version of Blender that worked as expected)

Short description of error
When an animated mesh (shape keys or armature) has multiple uv channels, it can't be exported in alembic format

Exact steps for others to reproduce the error
add a shape key to the default cube, animate the shape key value
add another UV channel
export as alembic

**System Information** Operating system: Windows-10-10.0.17134-SP0 64 Bits Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 445.87 **Blender Version** Broken: version: 2.83 (sub 17), branch: master, commit date: 2020-05-22 19:52, hash: `e8dd8c2829` Worked: (newest version of Blender that worked as expected) **Short description of error** When an animated mesh (shape keys or armature) has multiple uv channels, it can't be exported in alembic format **Exact steps for others to reproduce the error** add a shape key to the default cube, animate the shape key value add another UV channel export as alembic

Lance Phan commented

2020-05-24 12:51:55 +02:00

Added subscriber: @ssendam

Germano Cavalcante commented

2020-05-26 14:27:11 +02:00

Added subscribers: @dr.sybren, @mano-wii

Germano Cavalcante commented

2020-05-26 14:27:11 +02:00

I tested and this error message appeared:

Abc Export error: OCompoundProperty::init()
ERROR: EXCEPTION:
Already have a property named: UVMap

It appears that "UVMap" and "UVMap.001" are considered to have the same name.
@ssendam, is it the same error?

Here the file I tested:
tmp_alembic_bug.blend

@dr.sybren, is it an error or a limitation?

I tested and this error message appeared: ``` Abc Export error: OCompoundProperty::init() ERROR: EXCEPTION: Already have a property named: UVMap ``` It appears that "UVMap" and "UVMap.001" are considered to have the same name. @ssendam, is it the same error? Here the file I tested: [tmp_alembic_bug.blend](https://archive.blender.org/developer/F8555577/tmp_alembic_bug.blend) @dr.sybren, is it an error or a limitation?

Sybren A. Stüvel self-assigned this 2020-05-26 16:05:25 +02:00

Sybren A. Stüvel commented

2020-05-26 16:05:25 +02:00

@mano-wii This is caused by a side-effect of our exporting code's memory management (Alembic considers data "written" and "final" when its C++ objects go out of scope) in combination with my change in 65574463fa. I removed an "only export UVs on the first frame" clause because it was unclear why that was happening. As it turns out, it breaks exporting the 2nd (and subsequent) UV maps on an animated mesh. Effectively, on every frame the Alembic library thinks we want to create a new UV map, instead of continuing to write a new frame of data to the existing one.

@mano-wii This is caused by a side-effect of our exporting code's memory management (Alembic considers data "written" and "final" when its C++ objects go out of scope) in combination with my change in 65574463fa. I removed an "only export UVs on the first frame" clause because it was unclear why that was happening. As it turns out, it breaks exporting the 2nd (and subsequent) UV maps on an animated mesh. Effectively, on every frame the Alembic library thinks we want to create a new UV map, instead of continuing to write a new frame of data to the existing one.

blender-admin commented

2020-05-26 16:38:47 +02:00

This issue was referenced by a1c9d42584

This issue was referenced by a1c9d425844c5c2299daf9a89438d164f605407c

Sybren A. Stüvel commented

2020-05-26 16:44:27 +02:00

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

Sybren A. Stüvel closed this issue

2020-05-26 16:44:27 +02:00

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Export animated mesh to alembic fail when there are multiple UV maps #77021