Material Assignment broken when multiple materials assigned to Object #95417

New Issue

Erindale · 2022-02-02T03:47:55+01:00

Erindale commented

2022-02-02 03:47:55 +01:00

System Information
Operating system: Windows-10-10.0.22000-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 511.65

Blender Version
Broken: version: 3.0.1, branch: master, commit date: 2022-01-25 17:19, hash: dc2d180181

Short description of error
With multiple materials assigned to the Object data, the Set Material and Set Material Index nodes are non-functional on generated geometry.
With a Set Material followed by a Set Material Index node, you can get it to switch between index 0 and 1.
With just a Set Material node, you can only display Index 1.
With just a Set Material Index node, you can only display index 0.

Also happens in 3.1 builds.

Exact steps for others to reproduce the error
Create a node tree and generate geometry. Assign materials to the Object rather than mesh and attempt to use the Set Material or Set Material Index nodes to change them.

Attached file is set up accordingly.

2022-02-02 02-36-56.mp4

material bug.blend

**System Information** Operating system: Windows-10-10.0.22000-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 511.65 **Blender Version** Broken: version: 3.0.1, branch: master, commit date: 2022-01-25 17:19, hash: `dc2d180181` **Short description of error** With multiple materials assigned to the Object data, the Set Material and Set Material Index nodes are non-functional on generated geometry. With a Set Material followed by a Set Material Index node, you can get it to switch between index 0 and 1. With just a Set Material node, you can only display Index 1. With just a Set Material Index node, you can only display index 0. Also happens in 3.1 builds. **Exact steps for others to reproduce the error** Create a node tree and generate geometry. Assign materials to the Object rather than mesh and attempt to use the Set Material or Set Material Index nodes to change them. Attached file is set up accordingly. [2022-02-02 02-36-56.mp4](https://archive.blender.org/developer/F12841041/2022-02-02_02-36-56.mp4) [material bug.blend](https://archive.blender.org/developer/F12841046/material_bug.blend)

Erindale commented

2022-02-02 03:47:55 +01:00

Added subscriber: @Erindale

Pratik Borhade commented

2022-02-02 04:36:23 +01:00

Added subscriber: @PratikPB2123

Pratik Borhade commented

2022-02-02 04:36:23 +01:00

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

Pratik Borhade commented

2022-02-02 04:36:23 +01:00

Can confirm with mesh primitives.

Jacques Lucke commented

2022-02-02 12:14:11 +01:00

Added subscriber: @JacquesLucke

Jacques Lucke commented

2022-02-02 12:14:11 +01:00

The issue is that the generated mesh does not have as many material slots as the object. Currently, the "ground truth" for the number of materials is the number on the mesh. Therefore, if the object overwrites material slots that don't exist on the mesh, the overwrites are ignored.
This behavior is documented in the second to last paragraph in 1a81d268a1.
Fixing this should be possible, but I'm not quite sure how involved that would be currently.
Functions like DRW_curve_material_count_get and DRW_pointcloud_material_count_get would have to be updated to get the Object as parameter.

The issue is that the generated mesh does not have as many material slots as the object. Currently, the "ground truth" for the number of materials is the number on the mesh. Therefore, if the object overwrites material slots that don't exist on the mesh, the overwrites are ignored. This behavior is documented in the second to last paragraph in 1a81d268a1. Fixing this should be possible, but I'm not quite sure how involved that would be currently. Functions like `DRW_curve_material_count_get` and `DRW_pointcloud_material_count_get` would have to be updated to get the `Object` as parameter.

Dalai Felinto commented

2022-05-09 11:32:26 +02:00

Closed as duplicate of #87335

Dalai Felinto closed this issue

2022-05-09 11:32:26 +02:00

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Material Assignment broken when multiple materials assigned to Object #95417