OBJ/USD import: imported object has no active material, material has 2 users #100737

New Issue

Scurest · 2022-08-31T20:45:39+02:00

Scurest commented

2022-08-31 20:45:39 +02:00

Blender Version
Broken: 3.3.0 and 3.4.0
Worked: never?

Short description of error
Using the new importer, import an OBJ with a material. Check the Shader Editor. Nothing shows up even when the object is active. You have to click a material slot to get anything to show up. The object also has no active material (ob.active_material in Python). This seems to affect both USD and OBJ since 3.3 (probably started with D15145).

After you click a slot, you also notice the material has two users. Seems to affect all the importers written in C++ (Collada, USD, Alembic, OBJ), and seemingly has been an issue since "forever".

Neither issue exists in the Python importer.

**Blender Version** Broken: 3.3.0 and 3.4.0 Worked: never? **Short description of error** Using the new importer, import an OBJ with a material. Check the Shader Editor. Nothing shows up even when the object is active. You have to click a material slot to get anything to show up. The object also has no active material (`ob.active_material` in Python). This seems to affect both USD and OBJ since 3.3 (probably started with [D15145](https://archive.blender.org/developer/D15145)). ![iss1.png](https://archive.blender.org/developer/F13442004/iss1.png) After you click a slot, you also notice the material has two users. Seems to affect all the importers written in C++ (Collada, USD, Alembic, OBJ), and seemingly has been an issue since "forever". ![iss2.png](https://archive.blender.org/developer/F13442018/iss2.png) Neither issue exists in the Python importer.

Scurest commented

2022-08-31 20:45:39 +02:00

Added subscriber: @scurest

Germano Cavalcante commented

2022-08-31 21:30:30 +02:00

Added subscribers: @aras_p, @mano-wii

Germano Cavalcante commented

2022-08-31 21:30:30 +02:00

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

Germano Cavalcante commented

2022-08-31 21:30:30 +02:00

I can confirm the lack of active material and the strange 2 users (when only 1 was expected).
These were the files I used (exporting a Cube with material):
untitled.mtl
untitled.obj

@aras_p, is this something to worry about? (especially with the proximity of the D15777: obj: remove Python based obj importer/exporter addon (for 3.6+)).

(I also saw this other patch, I don't know if it has anything to do with the problem D15827: Fix invalid memory handling in C++ OBJ MTL Importer.).

I can confirm the lack of active material and the strange 2 users (when only 1 was expected). These were the files I used (exporting a Cube with material): [untitled.mtl](https://archive.blender.org/developer/F13442201/untitled.mtl) [untitled.obj](https://archive.blender.org/developer/F13442200/untitled.obj) @aras_p, is this something to worry about? (especially with the proximity of the [D15777: obj: remove Python based obj importer/exporter addon (for 3.6+)](https://archive.blender.org/developer/D15777)). --- (I also saw this other patch, I don't know if it has anything to do with the problem [D15827: Fix invalid memory handling in C++ OBJ MTL Importer.](https://archive.blender.org/developer/D15827)).

Jesse Yurkovich commented

2022-08-31 23:56:02 +02:00

Added subscriber: @deadpin

Jesse Yurkovich commented

2022-08-31 23:56:02 +02:00

USD has this issue as well; and it doesn't seem new. The importers must be forgetting a hidden step somewhere. The active_material_index is set to 0 but something in the system doesn't believe it's set.

USD has this issue as well; and it doesn't seem new. The importers must be forgetting a hidden step somewhere. The `active_material_index` is set to 0 but something in the system doesn't believe it's set.

Aras Pranckevicius self-assigned this 2022-09-01 05:52:42 +02:00

Aras Pranckevicius commented

2022-09-01 05:52:42 +02:00

I'll investigate both OBJ and USD.

Aras Pranckevicius changed title from ~~OBJ import: imported object has no active material, material has 2 users?~~ to OBJ/USD import: imported object has no active material, material has 2 users

2022-09-01 07:36:40 +02:00

blender-admin commented

2022-09-01 19:38:56 +02:00

This issue was referenced by f366d197db

This issue was referenced by f366d197db24cf611866a8d847b4022a6a46504e

Aras Pranckevicius commented

2022-09-01 19:39:08 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Aras Pranckevicius closed this issue

2022-09-01 19:39:08 +02:00

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

Bastien Montagne removed this from the Pipeline, Assets & IO project 2023-02-10 12:49:18 +01:00

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OBJ/USD import: imported object has no active material, material has 2 users #100737