Maniphest T96747

Support for USD PointInstancer
Confirmed, NormalTO DO
Actions

Assigned To
None
Authored By
Sam Wong (anthropoy)
Mar 24 2022, 5:22 AM
Tags
  • BF Blender
  • Pipeline, Assets & I/O
  • USD
Subscribers
Hans Goudey (HooglyBoogly)
Michael Kowalski (makowalski)
Philipp Oeser (lichtwerk)
Sam Wong (anthropoy)
Sybren A. Stüvel (sybren)
Trung Phạm (zNight)

Description

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.zip33 MBDownload

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

Event Timeline

Sam Wong (anthropoy) created this task.Mar 24 2022, 5:22 AM
Philipp Oeser (lichtwerk) changed the task status from Needs Triage to Needs Information from Developers.Mar 24 2022, 12:10 PM
Philipp Oeser (lichtwerk) added projects: Pipeline, Assets & I/O, USD.
Philipp Oeser (lichtwerk) added subscribers: Michael Kowalski (makowalski), Sybren A. Stüvel (sybren), Philipp Oeser (lichtwerk).

@Michael Kowalski (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 @Sybren A. Stüvel (sybren)

Michael Kowalski (makowalski) added a comment.Mar 24 2022, 3:36 PM
In T96747#1329193, @Philipp Oeser (lichtwerk) wrote:

@Michael Kowalski (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 @Sybren A. Stüvel (sybren)

Hello @Philipp Oeser (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 (anthropoy) added a comment.Mar 24 2022, 3:51 PM

Hi @Michael Kowalski (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 (makowalski) added a comment.Mar 24 2022, 3:56 PM

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

Michael Kowalski (makowalski) changed the task status from Needs Information from Developers to Confirmed.Mar 24 2022, 3:57 PM
Philipp Oeser (lichtwerk) renamed this task from Error loading USD file with point type to Support for USD PointInstancer.Mar 24 2022, 4:11 PM
Philipp Oeser (lichtwerk) changed the subtype of this task from "Report" to "To Do".
Bastien Montagne (mont29) moved this task from Backlog to Long-Term - Official on the Pipeline, Assets & I/O board.Mar 25 2022, 8:49 AM
Hans Goudey (HooglyBoogly) added a subscriber: Hans Goudey (HooglyBoogly).Mar 25 2022, 3:20 PM

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 (makowalski) added a comment.Mar 25 2022, 4:04 PM
In T96747#1330027, @Hans Goudey (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 @Hans Goudey (HooglyBoogly)! I'll investigate your suggestion.

Hans Goudey (HooglyBoogly) added a comment.Mar 28 2022, 7:46 PM

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 (makowalski) added a comment.Mar 28 2022, 8:04 PM
In T96747#1331137, @Hans Goudey (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 (zNight) added a subscriber: Trung Phạm (zNight).Jul 7 2022, 9:02 AM