Bundle shader node group assets for compatibility #113145

New Issue

Brecht Van Lommel · 2023-10-02T14:56:48+02:00

Brecht Van Lommel commented

2023-10-02 14:56:48 +02:00

When exporting shaders to other software, exporters usually do a best effort conversion from the Principled BSDF. However for users it is not obvious which inputs will work or not.

There is some standardization happening with glTF and OpenPBR, but it's still unlikely this will be solved entirely soon. Additionally for game engines it may be helpful to have inputs for image textures like normal maps, occlusion, thickness, etc.

To address this an idea is to add a number of shader group assets that under the hood will use the Principled BSDF or (only if necessary) other BSDF nodes. These can then hide parameters or expose additional ones.

Game Engines
- Specular workflow
- Metallic workflow
- Only support image datablock with image sockets?
- Differences between Unity, Godot, Unreal, .. ?
Disney BRDF
OpenPBR and Standard Surface
glTF

Exporters may need some changes to expand node groups to recognize the Principled BSDF. Or alternative not expand certain node groups that they recognize natively.

When exporting shaders to other software, exporters usually do a best effort conversion from the Principled BSDF. However for users it is not obvious which inputs will work or not. There is some standardization happening with glTF and OpenPBR, but it's still unlikely this will be solved entirely soon. Additionally for game engines it may be helpful to have inputs for image textures like normal maps, occlusion, thickness, etc. To address this an idea is to add a number of shader group assets that under the hood will use the Principled BSDF or (only if necessary) other BSDF nodes. These can then hide parameters or expose additional ones. * Game Engines * Specular workflow * Metallic workflow * Only support image datablock with image sockets? * Differences between Unity, Godot, Unreal, .. ? * Disney BRDF * OpenPBR and Standard Surface * glTF Exporters may need some changes to expand node groups to recognize the Principled BSDF. Or alternative not expand certain node groups that they recognize natively.

👍 2 🚀 2

Brecht Van Lommel added the

labels 2023-10-02 14:56:48 +02:00

Brecht Van Lommel commented

2023-10-02 15:01:48 +02:00

This is just an idea so far, but I've been thinking about this for a while so might as well make an issue. It came up in the context of removing the Specular BSDF that only works in EEVEE currently.

CC @fclem @JulienDuroure @LukasStockner

This is just an idea so far, but I've been thinking about this for a while so might as well make an issue. It came up in the context of removing the Specular BSDF that only works in EEVEE currently. CC @fclem @JulienDuroure @LukasStockner

Julien Duroure commented

2023-10-03 19:31:17 +02:00

Hello,

Some background regarding glTF:

Now, with 4.0 and new Principled, most of glTF can be handled by Principled itself. Only

Volume still needs a separate node + a socket in custom node group.
Occlusion is handled by a custom node group socket.
==> See 0 for custom group node created if needed

Here 1 is a file that can handle most of glTF data. (There is still Anisotropy that needs to be handle)

For most of parameter, glTF can handle factor and/or texture.
That means that for each Principled socket (for example BaseColor), we handle:

BaseColor.default_value if not linked
Texture if linked
Texture + multiply node if texture + factor
==> See 2

Current exporter version does not enter/exit node groups, but I have a PR ready, that should land in 4.1 (See 3)
Follow links entering and existing (possible recursively) is quite fastidious. Is there any chance to have an bpy API that automatically skip node group / reroute / etc... to keep link following as simple as possible in addons?

Regarding Godot, the current official workflow is to use .blend file as asset. Godot open Blender and export glTF in background, using my addon.

Hello, Some background regarding glTF: Now, with 4.0 and new Principled, most of glTF can be handled by Principled itself. Only - Volume still needs a separate node + a socket in custom node group. - Occlusion is handled by a custom node group socket. ==> See [0] for custom group node created if needed Here [1] is a file that can handle most of glTF data. (There is still Anisotropy that needs to be handle) For most of parameter, glTF can handle factor and/or texture. That means that for each Principled socket (for example BaseColor), we handle: - BaseColor.default_value if not linked - Texture if linked - Texture + multiply node if texture + factor ==> See [2] Current exporter version does not enter/exit node groups, but I have a PR ready, that should land in 4.1 (See [3]) Follow links entering and existing (possible recursively) is quite fastidious. Is there any chance to have an bpy API that automatically skip node group / reroute / etc... to keep link following as simple as possible in addons? Regarding Godot, the current official workflow is to use .blend file as asset. Godot open Blender and export glTF in background, using my addon. [0]: gltf_material_output.png [1]: 01_factors.blend [2]: factor_and_texture.png [3]: https://github.com/KhronosGroup/glTF-Blender-IO/pull/1735

factor_and_texture.png

42 KiB

01_factors.blend

1.0 MiB

gltf_material_output.png

16 KiB

Ludvik Koutny commented

2023-10-03 19:44:32 +02:00

Hello,

Some background regarding glTF:

Now, with 4.0 and new Principled, most of glTF can be handled by Principled itself. Only

Volume still needs a separate node + a socket in custom node group.

Occlusion is handled by a custom node group socket.
==> See 0 for custom group node created if needed

Here 1 is a file that can handle most of glTF data. (There is still Anisotropy that needs to be handle)

For most of parameter, glTF can handle factor and/or texture.
That means that for each Principled socket (for example BaseColor), we handle:

BaseColor.default_value if not linked

Texture if linked

Texture + multiply node if texture + factor
==> See 2

Current exporter version does not enter/exit node groups, but I have a PR ready, that should land in 4.1 (See 3)
Follow links entering and existing (possible recursively) is quite fastidious. Is there any chance to have an bpy API that automatically skip node group / reroute / etc... to keep link following as simple as possible in addons?

Regarding Godot, the current official workflow is to use .blend file as asset. Godot open Blender and export glTF in background, using my addon.

I never understood why GLTF did it in such an ugly and clunky way which creates node group datablock to clutter the blender file and tends to get constantly duplicated on imports/exports. Why wouldn't you just use named AOV Node which would be a perfect fit for this?

I know this is a bit of offtopic, but I would rather the GLTF exporter to get its stuff together in terms of how it handles material interop rather than if this poor idea which causes workflow issues spread further.

> Hello, > > Some background regarding glTF: > > Now, with 4.0 and new Principled, most of glTF can be handled by Principled itself. Only > - Volume still needs a separate node + a socket in custom node group. > - Occlusion is handled by a custom node group socket. > ==> See [0] for custom group node created if needed > > Here [1] is a file that can handle most of glTF data. (There is still Anisotropy that needs to be handle) > > For most of parameter, glTF can handle factor and/or texture. > That means that for each Principled socket (for example BaseColor), we handle: > - BaseColor.default_value if not linked > - Texture if linked > - Texture + multiply node if texture + factor > ==> See [2] > > Current exporter version does not enter/exit node groups, but I have a PR ready, that should land in 4.1 (See [3]) > Follow links entering and existing (possible recursively) is quite fastidious. Is there any chance to have an bpy API that automatically skip node group / reroute / etc... to keep link following as simple as possible in addons? > > Regarding Godot, the current official workflow is to use .blend file as asset. Godot open Blender and export glTF in background, using my addon. > > [0]: gltf_material_output.png > [1]: 01_factors.blend > [2]: factor_and_texture.png > [3]: https://github.com/KhronosGroup/glTF-Blender-IO/pull/1735 I never understood why GLTF did it in such an ugly and clunky way which creates node group datablock to clutter the blender file and tends to get constantly duplicated on imports/exports. Why wouldn't you just use named AOV Node which would be a perfect fit for this? I know this is a bit of offtopic, but I would rather the GLTF exporter to get its stuff together in terms of how it handles material interop rather than if this poor idea which causes workflow issues spread further.

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Bundle shader node group assets for compatibility #113145