User Structs / Custom Structs

Working with large sets of parameters in nodes is... annoying, to say the least, so...

Similar to Blueprint Structs in Unreal Engine, have a way to define custom structs of primitive values.

Instantiation of structs should be possible:

• As data-blocks in a table/dopesheet (?) panel
  • That is, let the user see/edit lists of same-typed structs.
• Via inline properties to be passed into geo-nodes.
• Via 'Combine X' nodes in geometry nodes.
• ?

Usage of structs should be possible:

• As types for noddles/fields in geo-nodes.
  • 'Separate X' nodes in geometry nodes.
• In materials? (i.e. "uniform blocks")
• As (mesh) attributes?

Non-Goals: (for an initial implementation)

• More complex types, such as strings, enums and data-blocks.
  • Links to data-blocks should be the next step.
• Recursion of structs within structs.

Issues:

• How to handle changes to the struct layout? (i.e. versioning)
• How to deal with the variable sizes of different structs?