Alembic is exporting objects with geometry nodes as empty objects. #89649

New Issue

kursad k · 2021-07-05T02:43:38+02:00

kursad k commented

2021-07-05 02:43:38 +02:00

System Information
Operating system: Windows 10
Graphics card: 2070

Blender Version
Broken: blender-3.0.0-alpha+master.b73dc36859e0-windows.amd64-release

Short description of error

Alembic export does not seem to understand objects with the geometry nodes modifier properly. The resulting .abc file does not seem to contain the intended object when imported back. Basically it is not evaluating the mesh during export.

Exact steps for others to reproduce the error

Open the attached .blend
Select the "GeometryNode" objects from the outliner.
Open File/Export/Alembic
Make sure you only have "Selected Objects" selected in the options so it only exports the selected objects.
Bear in mind we are only exporting the object with the geometry nodes mod, the resulting import should be a single combined mesh
Export it
Import the .alembic file back
You should have an empty "GeometryNode.001" shell object. If the resulting import has more multiple objects then you exported other objects in the scene too, which goes against the basic premise of this test.

_04072021_1929_51.blend

**System Information** Operating system: Windows 10 Graphics card: 2070 **Blender Version** Broken: blender-3.0.0-alpha+master.b73dc36859e0-windows.amd64-release **Short description of error** Alembic export does not seem to understand objects with the geometry nodes modifier properly. The resulting .abc file does not seem to contain the intended object when imported back. Basically it is not evaluating the mesh during export. ![image.png](https://archive.blender.org/developer/F10211471/image.png) **Exact steps for others to reproduce the error** - Open the attached .blend - Select the "GeometryNode" objects from the outliner. - Open File/Export/Alembic - Make sure you only have "Selected Objects" selected in the options so it only exports the selected objects. - Bear in mind we are only exporting the object with the geometry nodes mod, the resulting import should be a single combined mesh - Export it - Import the .alembic file back - You should have an empty "GeometryNode.001" shell object. If the resulting import has more multiple objects then you exported other objects in the scene too, which goes against the basic premise of this test. [_04072021_1929_51.blend](https://archive.blender.org/developer/F10211470/_04072021_1929_51.blend)

kursad k commented

2021-07-05 02:43:38 +02:00

Added subscriber: @kursadk

Pratik Borhade commented

2021-07-05 03:17:39 +02:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2021-07-05 03:17:39 +02:00

Can confirm with the attached file for version 3.0.0 (2d146b61d8)

Could you please add the steps to recreate the scene?

From scratch I can not reproduce.

Can confirm with the attached file for version 3.0.0 (`2d146b61d8`) Could you please add the steps to recreate the scene? From scratch I can not reproduce.

Pratik Borhade commented

2021-07-05 04:34:30 +02:00

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

kursad k commented

2021-07-05 19:14:32 +02:00

You need to use the kind of geometry nodes set up that is in the .blend file There are cases where it exports, and in some other cases it cant. I attached the one that it can't export.

Pratik Borhade commented

2021-07-06 06:56:58 +02:00

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

Pratik Borhade commented

2021-07-06 07:16:28 +02:00

Added subscriber: @lichtwerk

Pratik Borhade commented

2021-07-06 07:16:28 +02:00

Hi @kursadk , I am not able to reproduce from scratch

#89649.blend

@lichtwerk , are you able to reproduce?

Hi @kursadk , I am not able to reproduce from scratch [#89649.blend](https://archive.blender.org/developer/F10213062/T89649.blend) @lichtwerk , are you able to reproduce?

Philipp Oeser commented

2021-07-06 12:16:47 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Philipp Oeser commented

2021-07-06 12:16:47 +02:00

Added subscribers: @JacquesLucke, @dr.sybren

Philipp Oeser commented

2021-07-06 12:16:47 +02:00

This is because the source collection is disabled for rendering (Camera icon in the Outliner).
@PratikPB2123 : if you do this in your file it will "fail" as well.

Alembic always evaluates the depsgraph in render mode, so that might make a bit of sense, otoh, this is is not the setting on the object to export, so not sure here actually.
@JacquesLucke , @dr.sybren : is this expected behavior?

This is because the source collection is disabled for rendering (Camera icon in the Outliner). @PratikPB2123 : if you do this in your file it will "fail" as well. Alembic always evaluates the depsgraph in render mode, so that might make a bit of sense, otoh, this is is not the setting on the object to export, so not sure here actually. @JacquesLucke , @dr.sybren : is this expected behavior?

Jacques Lucke commented

2021-07-06 12:44:52 +02:00

Bear in mind we are only exporting the object with the geometry nodes mod, the resulting import should be a single combined mesh

I'm not entirely sure about this. Note that in geometry nodes the collection is still treated as an instance until it is realized (which doesn't happen here currently). Sometimes it makes sense to create a combined mesh from all the instances and sometimes it doesn't. I'm not sure how alembic generally handles instances.
You could force geometry nodes to combine the instances into a single mesh e.g. by using an Attribute Fill after the Collection Info node. Check the spreadsheet to see what data you are working with. Note, you might run into issues related to #89054 when making the instances real, e.g. the uv layers don't work as you expect anymore.

> Bear in mind we are only exporting the object with the geometry nodes mod, the resulting import should be a single combined mesh I'm not entirely sure about this. Note that in geometry nodes the collection is still treated as an instance until it is realized (which doesn't happen here currently). Sometimes it makes sense to create a combined mesh from all the instances and sometimes it doesn't. I'm not sure how alembic generally handles instances. You could force geometry nodes to combine the instances into a single mesh e.g. by using an Attribute Fill after the Collection Info node. Check the spreadsheet to see what data you are working with. Note, you might run into issues related to #89054 when making the instances real, e.g. the uv layers don't work as you expect anymore.

Sybren A. Stüvel commented

2021-07-06 14:09:31 +02:00

When rendering the file from the report description, I also don't see anything in the camera view. This means that the Alembic exporter is doing the expected thing. However, when I apply D11820: Alembic export: evaluation mode option and export with Viewport evaluation, things don't export well. I do see a marked-as-invisible Suzanne (the original, invisible object), but the geometry spawned by the geometry nodes is missing. It does contain the transform, though:

ABC
 |--Light
 |--Camera
 |    `--Camera
 |--_TRACK
 |--GeometryNode
 |    |--Plane       ← this is just the XForm
 |    |--Suzanne--1  ← this is just the XForm
 |    `--Torus--1    ← this is just the XForm
 |--Suzanne
 |    `--Suzanne     ← this is the actual mesh
 `--Torus
     `--Torus        ← this is the actual mesh

When rendering the file from the report description, I also don't see anything in the camera view. This means that the Alembic exporter is doing the expected thing. However, when I apply [D11820: Alembic export: evaluation mode option](https://archive.blender.org/developer/D11820) and export with Viewport evaluation, things don't export well. I do see a marked-as-invisible Suzanne (the original, invisible object), but the geometry spawned by the geometry nodes is missing. It does contain the transform, though: ``` ABC |--Light |--Camera | `--Camera |--_TRACK |--GeometryNode | |--Plane ← this is just the XForm | |--Suzanne--1 ← this is just the XForm | `--Torus--1 ← this is just the XForm |--Suzanne | `--Suzanne ← this is the actual mesh `--Torus `--Torus ← this is the actual mesh ```

Sybren A. Stüvel commented

2021-07-06 14:34:29 +02:00

In #89649#1187539, @JacquesLucke wrote:
You could force geometry nodes to combine the instances into a single mesh e.g. by using an Attribute Fill after the Collection Info node.

So I guess that Geometry Nodes modifier doesn't actually produce an evaluated mesh that contains the entire geometry. Do I guess correctly?

> In #89649#1187539, @JacquesLucke wrote: > You could force geometry nodes to combine the instances into a single mesh e.g. by using an Attribute Fill after the Collection Info node. So I guess that Geometry Nodes modifier doesn't actually produce an evaluated mesh that contains the entire geometry. Do I guess correctly?

kursad k commented

2021-07-06 18:34:22 +02:00

In #89649#1187643, @dr.sybren wrote:

In #89649#1187539, @JacquesLucke wrote:
You could force geometry nodes to combine the instances into a single mesh e.g. by using an Attribute Fill after the Collection Info node.

So I guess that Geometry Nodes modifier doesn't actually produce an evaluated mesh that contains the entire geometry. Do I guess correctly?

I can confirm this. See the video below Create duplicate for editing (which I used in the video) comes withthe corrrective shapekeys addon and creates a duplicate by evaluating the graph.

PNxH1vxKth.mp4

> In #89649#1187643, @dr.sybren wrote: >> In #89649#1187539, @JacquesLucke wrote: >> You could force geometry nodes to combine the instances into a single mesh e.g. by using an Attribute Fill after the Collection Info node. > > So I guess that Geometry Nodes modifier doesn't actually produce an evaluated mesh that contains the entire geometry. Do I guess correctly? I can confirm this. See the video below **Create duplicate for editing** (which I used in the video) comes with**the corrrective shapekeys** addon and creates a duplicate by evaluating the graph. [PNxH1vxKth.mp4](https://archive.blender.org/developer/F10213965/PNxH1vxKth.mp4)

kursad k commented

2021-07-06 18:42:16 +02:00

In #89649#1187539, @JacquesLucke wrote:

Bear in mind we are only exporting the object with the geometry nodes mod, the resulting import should be a single combined mesh

I'm not entirely sure about this. Note that in geometry nodes the collection is still treated as an instance until it is realized (which doesn't happen here currently). Sometimes it makes sense to create a combined mesh from all the instances and sometimes it doesn't. I'm not sure how alembic generally handles instances.
You could force geometry nodes to combine the instances into a single mesh e.g. by using an Attribute Fill after the Collection Info node. Check the spreadsheet to see what data you are working with. Note, you might run into issues related to #89054 when making the instances real, e.g. the uv layers don't work as you expect anymore.

Well forcing with an additional node destroys the UVs completely. And for multiple meshes (from a collection node ) like that there is not an easy way to get those uvs back on the resulting mesh. See the video please.

zwE1GvL5g9.mp4

> In #89649#1187539, @JacquesLucke wrote: >> Bear in mind we are only exporting the object with the geometry nodes mod, the resulting import should be a single combined mesh > > I'm not entirely sure about this. Note that in geometry nodes the collection is still treated as an instance until it is realized (which doesn't happen here currently). Sometimes it makes sense to create a combined mesh from all the instances and sometimes it doesn't. I'm not sure how alembic generally handles instances. > You could force geometry nodes to combine the instances into a single mesh e.g. by using an Attribute Fill after the Collection Info node. Check the spreadsheet to see what data you are working with. Note, you might run into issues related to #89054 when making the instances real, e.g. the uv layers don't work as you expect anymore. Well forcing with an additional node destroys the UVs completely. And for multiple meshes (from a collection node ) like that there is not an easy way to get those uvs back on the resulting mesh. See the video please. [zwE1GvL5g9.mp4](https://archive.blender.org/developer/F10213967/zwE1GvL5g9.mp4)

Jacques Lucke commented

2021-11-19 11:20:15 +01:00

So I guess that Geometry Nodes modifier doesn't actually produce an evaluated mesh that contains the entire geometry. Do I guess correctly?

Depends, it can merge everything into a single mesh by using the Realize Instances node. However, since Blender 3.0 we support geometry instances, i.e. the final evaluated state of an object can contain multiple separate instances, whereby the individual meshes are all generated within one object. We added support for eevee and cycles already, but did not have enough time to fix exporters (objects that don't use geometry instances are not affected). Updating exporters is on our list of targets for 3.1 (#93203).

> So I guess that Geometry Nodes modifier doesn't actually produce an evaluated mesh that contains the entire geometry. Do I guess correctly? Depends, it can merge everything into a single mesh by using the `Realize Instances` node. However, since Blender 3.0 we support geometry instances, i.e. the final evaluated state of an object can contain multiple separate instances, whereby the individual meshes are all generated within one object. We added support for eevee and cycles already, but did not have enough time to fix exporters (objects that don't use geometry instances are not affected). Updating exporters is on our list of targets for 3.1 (#93203).

Maurice Carlberg commented

2021-11-19 14:45:24 +01:00

Added subscriber: @Morix

Maurice Carlberg commented

2021-11-19 14:45:24 +01:00

In #89649#1256274, @JacquesLucke wrote:

So I guess that Geometry Nodes modifier doesn't actually produce an evaluated mesh that contains the entire geometry. Do I guess correctly?

Depends, it can merge everything into a single mesh by using the Realize Instances node. However, since Blender 3.0 we support geometry instances, i.e. the final evaluated state of an object can contain multiple separate instances, whereby the individual meshes are all generated within one object. We added support for eevee and cycles already, but did not have enough time to fix exporters (objects that don't use geometry instances are not affected). Updating exporters is on our list of targets for 3.1 (#93203).

Would be awesome to have instances become real meshes (like Animation Nodes) that could be rebaked for us who create 3D animation and content for web3D. I was able to export a bunch of animated instances in alembic (Blender 2.93.2) and then reimport them and then bake them and have separated animations to each object and then export them to glb. Actually, I´m trying to figure out a way to do this in 3.0, is there any workaround combining it with AN maybe? or am I doomed to re do it in 2.93 until release of 3.1? Tnx for an amazing work you guys already do btw

> In #89649#1256274, @JacquesLucke wrote: >> So I guess that Geometry Nodes modifier doesn't actually produce an evaluated mesh that contains the entire geometry. Do I guess correctly? > > Depends, it can merge everything into a single mesh by using the `Realize Instances` node. However, since Blender 3.0 we support geometry instances, i.e. the final evaluated state of an object can contain multiple separate instances, whereby the individual meshes are all generated within one object. We added support for eevee and cycles already, but did not have enough time to fix exporters (objects that don't use geometry instances are not affected). Updating exporters is on our list of targets for 3.1 (#93203). Would be awesome to have instances become real meshes (like Animation Nodes) ![image.png](https://archive.blender.org/developer/F11828727/image.png) that could be rebaked for us who create 3D animation and content for web3D. I was able to export a bunch of animated instances in alembic (Blender 2.93.2) and then reimport them and then bake them and have separated animations to each object and then export them to glb. Actually, I´m trying to figure out a way to do this in 3.0, is there any workaround combining it with AN maybe? or am I doomed to re do it in 2.93 until release of 3.1? Tnx for an amazing work you guys already do btw

Philipp Oeser removed the

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Alembic is exporting objects with geometry nodes as empty objects. #89649