Support for USD PointInstancer #96747

New Issue

Sam Wong · 2022-03-24T05:22:34+01:00

Sam Wong commented

2022-03-24 05:22:34 +01:00

System Information
Operating system: Win10
Graphics card: GTX 1660 Ti

Blender Version
Broken: 3.1

Short description of error
After loading a USD file with type particleInstancer attached with spheres as child, Blender failed to draw the points as spheres. Instead, the displayed object in the layout window is just a singular point at the origin. Example file attached.example_sim_granular.zip

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).

**System Information** Operating system: Win10 Graphics card: GTX 1660 Ti **Blender Version** Broken: 3.1 **Short description of error** After loading a USD file with type particleInstancer attached with spheres as child, Blender failed to draw the points as spheres. Instead, the displayed object in the layout window is just a singular point at the origin. Example file attached.[example_sim_granular.zip](https://archive.blender.org/developer/F12942071/example_sim_granular.zip) **Exact steps for others to reproduce the error** Based on the default startup or an attached .blend file (as simple as possible).

Sam Wong commented

2022-03-24 05:22:34 +01:00

Added subscriber: @anthropoy

Philipp Oeser commented

2022-03-24 12:10:19 +01:00

Added subscribers: @makowalski, @dr.sybren, @lichtwerk

Philipp Oeser commented

2022-03-24 12:10:19 +01:00

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

Philipp Oeser commented

2022-03-24 12:10:19 +01:00

@makowalski : havent gotten to building USD to get access to utils that let me examine a.usd the same way I can examine an alembic .abc (so I cannot really tell how the USD looks from the inside), but I assume this is not implemented yet?
For me, a single empty is imported here (under another empty for the particle system under another empty as the root).
Also not sure if the plans are to do it like alembic in blender [which imports verts with meshsequence cache modifier for plain particles or objects with transform caches for instanced particles afaict], or if this will somehow end up on the pointcloud type?

CC @dr.sybren

@makowalski : havent gotten to building USD to get access to utils that let me examine a.usd the same way I can examine an alembic .abc (so I cannot really tell how the USD looks from the inside), but I assume this is not implemented yet? For me, a single empty is imported here (under another empty for the particle system under another empty as the root). Also not sure if the plans are to do it like alembic in blender [which imports verts with meshsequence cache modifier for plain particles or objects with transform caches for instanced particles afaict], or if this will somehow end up on the pointcloud type? CC @dr.sybren

Michael Kowalski commented

2022-03-24 15:36:31 +01:00

In #96747#1329193, @lichtwerk wrote:
@makowalski : havent gotten to building USD to get access to utils that let me examine a.usd the same way I can examine an alembic .abc (so I cannot really tell how the USD looks from the inside), but I assume this is not implemented yet?
For me, a single empty is imported here (under another empty for the particle system under another empty as the root).
Also not sure if the plans are to do it like alembic in blender [which imports verts with meshsequence cache modifier for plain particles or objects with transform caches for instanced particles afaict], or if this will somehow end up on the pointcloud type?

CC @dr.sybren

Hello @lichtwerk. In this case, the USD contains a PointInstancer. Indeed, this hasn't been implemented yet. (In the universal-scene-description branch there is support for importing scene instances but not point instances.) I am leaning towards importing PointInstancers into Blender as particle systems with particles represented as meshes. But this is open to discussion, of course, and we could potentially provide more than one option. Regardless, supporting point instancing is an important feature I was planning to add.

> In #96747#1329193, @lichtwerk wrote: > @makowalski : havent gotten to building USD to get access to utils that let me examine a.usd the same way I can examine an alembic .abc (so I cannot really tell how the USD looks from the inside), but I assume this is not implemented yet? > For me, a single empty is imported here (under another empty for the particle system under another empty as the root). > Also not sure if the plans are to do it like alembic in blender [which imports verts with meshsequence cache modifier for plain particles or objects with transform caches for instanced particles afaict], or if this will somehow end up on the pointcloud type? > > CC @dr.sybren Hello @lichtwerk. In this case, the USD contains a PointInstancer. Indeed, this hasn't been implemented yet. (In the `universal-scene-description` branch there is support for importing scene instances but not point instances.) I am leaning towards importing PointInstancers into Blender as particle systems with particles represented as meshes. But this is open to discussion, of course, and we could potentially provide more than one option. Regardless, supporting point instancing is an important feature I was planning to add.

Sam Wong commented

2022-03-24 15:51:08 +01:00

Hi @makowalski, it would be great to have the option that the PointInstancers be imported as particle systems and the particles to be represented by the "child" attached to the PointInstancers.

Michael Kowalski commented

2022-03-24 15:56:44 +01:00

Thank you for the feedback @anthropoy. I am investigating this option and will post progress in this task.

Michael Kowalski commented

2022-03-24 15:57:36 +01:00

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

Philipp Oeser changed title from ~~Error loading USD file with point type~~ to Support for USD PointInstancer

2022-03-24 16:11:28 +01:00

Hans Goudey commented

2022-03-25 15:20:52 +01:00

Added subscriber: @HooglyBoogly

Hans Goudey commented

2022-03-25 15:20:52 +01:00

it would be great to have the option that the PointInstancers be imported as particle systems

Since the old particle system is deprecated, I don't think this is the right approach. Without more knowledge of USD I'm not sure what to suggest instead, but I would think something using the same type of instances generated by geometry nodes would be preferable (see InstancesComponent). That has support for arbitrary generic attributes on instances.

> it would be great to have the option that the PointInstancers be imported as particle systems Since the old particle system is deprecated, I don't think this is the right approach. Without more knowledge of USD I'm not sure what to suggest instead, but I would think something using the same type of instances generated by geometry nodes would be preferable (see `InstancesComponent`). That has support for arbitrary generic attributes on instances.

Michael Kowalski commented

2022-03-25 16:04:24 +01:00

In #96747#1330027, @HooglyBoogly wrote:

it would be great to have the option that the PointInstancers be imported as particle systems

Since the old particle system is deprecated, I don't think this is the right approach. Without more knowledge of USD I'm not sure what to suggest instead, but I would think something using the same type of instances generated by geometry nodes would be preferable (see InstancesComponent). That has support for arbitrary generic attributes on instances.

Thanks @HooglyBoogly! I'll investigate your suggestion.

> In #96747#1330027, @HooglyBoogly wrote: >> it would be great to have the option that the PointInstancers be imported as particle systems > Since the old particle system is deprecated, I don't think this is the right approach. Without more knowledge of USD I'm not sure what to suggest instead, but I would think something using the same type of instances generated by geometry nodes would be preferable (see `InstancesComponent`). That has support for arbitrary generic attributes on instances. Thanks @HooglyBoogly! I'll investigate your suggestion.

Hans Goudey commented

2022-03-28 19:46:55 +02:00

I'm guessing here a bit, but one approach would be creating a point cloud with a geometry nodes modifier that uses the Instance on Points node. All of the instances could go in a collection, and the point cloud could have an instance_index attribute used to choose the correct instance.

I'm guessing here a bit, but one approach would be creating a point cloud with a geometry nodes modifier that uses the `Instance on Points` node. All of the instances could go in a collection, and the point cloud could have an `instance_index` attribute used to choose the correct instance.

Michael Kowalski commented

2022-03-28 20:04:22 +02:00

In #96747#1331137, @HooglyBoogly wrote:
I'm guessing here a bit, but one approach would be creating a point cloud with a geometry nodes modifier that uses the Instance on Points node. All of the instances could go in a collection, and the point cloud could have an instance_index attribute used to choose the correct instance.

Yes, that sounds like a promising approach!

> In #96747#1331137, @HooglyBoogly wrote: > I'm guessing here a bit, but one approach would be creating a point cloud with a geometry nodes modifier that uses the `Instance on Points` node. All of the instances could go in a collection, and the point cloud could have an `instance_index` attribute used to choose the correct instance. Yes, that sounds like a promising approach!

Trung Phạm commented

2022-07-07 09:02:02 +02:00

Added subscriber: @zNight

Bastien Montagne added this to the Pipeline, Assets & IO project 2023-02-09 15:40:38 +01:00

Philipp Oeser removed the

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Support for USD PointInstancer #96747