Volume scatter and absorption shaders do not work with mesh to volume modifier in eevee #103683

New Issue

Wouter Stomp · 2023-01-06T12:49:22+01:00

Wouter Stomp commented

2023-01-06 12:49:22 +01:00

System Information
Operating system: macOS-13.1-arm64-arm-64bit 64 Bits
Graphics card: Metal API Apple M1 Max 1.2

Blender Version
Broken: 3.2.1; version: 3.5.0 Alpha, branch: master, commit date: 2023-01-06 00:40, hash: bc5337a05a
Worked: unknown

Short description of error
When using the mesh to volume modifier, volumes are not visible with the volume scatter and absorption shaders in eevee. They are visible with the principled volume shader. They are also visible when using the geometry nodes mesh to volume node instead of the modifier.

Additionally a very specific bug occurs: when I have the scatter or absorption node attached, then go to eevee rendered view, switch back to cycles rendered view and then attach the principled volume, the geonodes volume becomes invisible. That becomes visible again when I manipulate the blackbody intensity value (but not any of the other values in the shader node).

Exact steps for others to reproduce the error
See attached blend file
When in viewport shading or eevee rendered view, the cube with the mesh to volume modifier does not render when volume scatter or absorption nodes are connected. Attach the principled volume node and it does render.

Volume shader test.blend

**System Information** Operating system: macOS-13.1-arm64-arm-64bit 64 Bits Graphics card: Metal API Apple M1 Max 1.2 **Blender Version** Broken: 3.2.1; version: 3.5.0 Alpha, branch: master, commit date: 2023-01-06 00:40, hash: `bc5337a05a` Worked: unknown **Short description of error** When using the mesh to volume modifier, volumes are not visible with the volume scatter and absorption shaders in eevee. They are visible with the principled volume shader. They are also visible when using the geometry nodes mesh to volume node instead of the modifier. Additionally a very specific bug occurs: when I have the scatter or absorption node attached, then go to eevee rendered view, switch back to cycles rendered view and then attach the principled volume, the geonodes volume becomes invisible. That becomes visible again when I manipulate the blackbody intensity value (but not any of the other values in the shader node). **Exact steps for others to reproduce the error** See attached blend file When in viewport shading or eevee rendered view, the cube with the mesh to volume modifier does not render when volume scatter or absorption nodes are connected. Attach the principled volume node and it does render. [Volume shader test.blend](https://archive.blender.org/developer/F14120725/Volume_shader_test.blend)

Wouter Stomp commented

2023-01-06 12:49:22 +01:00

Added subscriber: @blenderrocket

Michael Parkin-White commented

2023-01-06 12:54:10 +01:00

Added subscriber: @Michael-Parkin-White-Apple

Germano Cavalcante commented

2023-01-09 19:55:13 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2023-01-09 19:55:13 +01:00

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

Germano Cavalcante commented

2023-01-09 19:55:13 +01:00

It is indeed strange that Eevee and Cycles behave differently with this material.
On the one hand I can understand the Eevee side that needs to read attributes like "density" to represent a volume.
Cycles seems to initialize a value for each Voxel.

I'm not sure if it's a bug.

It is indeed strange that Eevee and Cycles behave differently with this material. On the one hand I can understand the Eevee side that needs to read attributes like "density" to represent a volume. Cycles seems to initialize a value for each Voxel. I'm not sure if it's a bug.

Wouter Stomp commented

2023-01-10 09:25:54 +01:00

The difference is mainly within eevee depending on how the volume is generated (volume to mesh modifier vs the other two methods). The density attribute is also used by the principled volume shader and that doesn't have this issue.

Wouter Stomp commented

2023-11-03 16:38:19 +01:00

This also affects Eevee next:

With the volume scatter node connected none of the cubes appear
With the volume absorption node connected only the the cube with the volume shader appears
With the principled volume node connected all three appear correctly

This also affects Eevee next: - With the volume scatter node connected none of the cubes appear - With the volume absorption node connected only the the cube with the volume shader appears - With the principled volume node connected all three appear correctly

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Volume scatter and absorption shaders do not work with mesh to volume modifier in eevee #103683