Vector Transform Material Node has Unexpected Behavior with Geometry Node Instances #112801

New Issue

Bloop Trangle · 2023-09-24T08:52:11+02:00

Bloop Trangle commented

2023-09-24 08:52:11 +02:00

System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: AMD Radeon RX 7900 XTX ATI Technologies Inc. 4.5.0 Core Profile Context 23.9.2.230911

Blender Version
Broken: version: 3.6.3, branch: blender-v3.6-release, commit date: 2023-09-21 06:06, hash: d3e6b08276ba

Short description of error
A Vector Transform node set Object to World and taking an instancer attribute seems to transform the attribute based on the Instance space rather than the Objects. I'd expect Object space to behave the same regardless of whats inside the object. It has unexpected results when instances are rotated, and when there are nested instances assigned the same attribute. If this isn't a bug and instances just count as an Object for the Vector Transform node, then maybe there should be an Instance space option added to it with the current behavior, and Object space should be corrected to behave the same as when the instances are realized.

Exact steps for others to reproduce the error
FILE DESCRIPTION: I created a simple blend file to make it easy to see the effects. There's a Geo Node modifier that creates an instance heirarchy, with the position of the top level instances being stored as an attribute on the sub instances. There are some switches set up on the geo node modifier, and there's a driver on the Attribute nodes Type to change it between Geometry and Instancer just to match the Realize Instances option on the geo nodes.

USAGE: Set the viewport shading to Rendered. The settings to play with are on the geo nodes modifer and in the material nodes:

Random Rotations and Realize Instances on the geo nodes modifier.
The Point and Vector options on the Vector Transform node in the material.
Rotating the model to see the attribute space being transformed from Object to World space.

EXPECTED: The setup in the file with Realize Instances enabled behaves as expected.

Each icosphere cluster is a single color and aligns with the world axis. Enabling Random Rotations, switching between Point/Vector, or rotating the model doesn't change this.
Only difference between Point and Vector on the Vector Transform node is Point is bluer, as the model is raised 1m.

UNEXPECTED: The setup in the file with Realize Instances disabled in the geo nodes modifier is expected to behave the same as above, but is different in the following ways:

Realize Instances toggled on/off, Vector Transform set to Vector, Random Rotations off: Colors darken slightly.
Realize Instances on, Random Rotations toggled on/off: Cluster colors are scrambled.
Realize Instances on, Vector Transform set to Point: The individual icosphere instances in each cluster are now different colors.

**System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: AMD Radeon RX 7900 XTX ATI Technologies Inc. 4.5.0 Core Profile Context 23.9.2.230911 **Blender Version** Broken: version: 3.6.3, branch: blender-v3.6-release, commit date: 2023-09-21 06:06, hash: `d3e6b08276ba` **Short description of error** A Vector Transform node set Object to World and taking an instancer attribute seems to transform the attribute based on the Instance space rather than the Objects. I'd expect Object space to behave the same regardless of whats inside the object. It has unexpected results when instances are rotated, and when there are nested instances assigned the same attribute. If this isn't a bug and instances just count as an Object for the Vector Transform node, then maybe there should be an Instance space option added to it with the current behavior, and Object space should be corrected to behave the same as when the instances are realized. **Exact steps for others to reproduce the error** FILE DESCRIPTION: I created a simple blend file to make it easy to see the effects. There's a Geo Node modifier that creates an instance heirarchy, with the position of the top level instances being stored as an attribute on the sub instances. There are some switches set up on the geo node modifier, and there's a driver on the Attribute nodes Type to change it between Geometry and Instancer just to match the Realize Instances option on the geo nodes. USAGE: Set the viewport shading to Rendered. The settings to play with are on the geo nodes modifer and in the material nodes: - Random Rotations and Realize Instances on the geo nodes modifier. - The Point and Vector options on the Vector Transform node in the material. - Rotating the model to see the attribute space being transformed from Object to World space. EXPECTED: The setup in the file with Realize Instances enabled behaves as expected. - Each icosphere cluster is a single color and aligns with the world axis. Enabling Random Rotations, switching between Point/Vector, or rotating the model doesn't change this. - Only difference between Point and Vector on the Vector Transform node is Point is bluer, as the model is raised 1m. UNEXPECTED: The setup in the file with Realize Instances disabled in the geo nodes modifier is expected to behave the same as above, but is different in the following ways: - Realize Instances toggled on/off, Vector Transform set to Vector, Random Rotations off: Colors darken slightly. - Realize Instances on, Random Rotations toggled on/off: Cluster colors are scrambled. - Realize Instances on, Vector Transform set to Point: The individual icosphere instances in each cluster are now different colors.

vectorTransformNode_debugging.blend

956 KiB

vectorTransformNode_debuggingFile.png

552 KiB

Bloop Trangle added the

labels 2023-09-24 08:52:11 +02:00

Bloop Trangle changed title from ~~Vector Transform Meterial Node Unexpected Behavior with Geometry Node Instances~~ to Vector Transform Material Node has Unexpected Behavior with Geometry Node Instances

2023-09-24 08:54:48 +02:00

Germano Cavalcante commented

2023-09-25 17:35:25 +02:00

Thanks for the report, @Bloop, but I believe this behavior is expected.
Each instance is considered a unique object (with its own space, with its own ID).
This is clear with other nodes like Object Info > Randon.

Unfortunately I don't know a simple way to reference the space of a specific object in the scene.

Maybe the Vector Transform could have a "From Instancer" option or something like "From Object: X". But this already becomes a feature request.

For user feedback and feature requests we have other channels: https://wiki.blender.org/wiki/Communication/Contact#User_Feedback_and_Requests

Not a bug AFAICS, so closing.

Feel free to comment if there is misunderstanding.

Thanks for the report, @Bloop, but I believe this behavior is expected. Each instance is considered a unique object (with its own space, with its own ID). This is clear with other nodes like `Object Info` > `Randon`. Unfortunately I don't know a simple way to reference the space of a specific object in the scene. Maybe the `Vector Transform` could have a "From Instancer" option or something like "From Object: X". But this already becomes a feature request. For user feedback and feature requests we have other channels: https://wiki.blender.org/wiki/Communication/Contact#User_Feedback_and_Requests Not a bug AFAICS, so closing. Feel free to comment if there is misunderstanding.

👍 1

Germano Cavalcante closed this issue

2023-09-25 17:35:31 +02:00

Blender Bot added

and removed

labels 2023-09-25 17:35:33 +02:00

Sign in to join this conversation.