Import custom attributes with GLTFDocumentExtension

[huwpascoe]

Proposal

Import ARRAY_CUSTOM# attributes with GLTFDocumentExtension using a function to specify layer name. Also added "Export Attributes" checkbox to the blender importer.
godotengine/godot-proposals#10892

Test Project

custom_attrib_test.zip

changes

• Swapped the function around, accepts Mesh.ArrayType, returns a string. (empty string for default behavior)
• Added the GLTFState and current mesh index to the function

extends GLTFDocumentExtension

func _get_attribute_for_mesh_array(state: GLTFState, mesh_index: int, mesh_array: Mesh.ArrayType) -> String:
	var mesh_name: String = state.json["meshes"][mesh_index]["name"]

	if mesh_array == Mesh.ARRAY_COLOR:
		match mesh_name:
			"mesh_1": return "COLOR_1"
			"mesh_2": return "_MY_DATA"

	if mesh_name == "custom":
		match mesh_array:
			Mesh.ARRAY_TEX_UV: return "TEXCOORD_1"
			Mesh.ARRAY_CUSTOM0: return "_ROCK"
			Mesh.ARRAY_CUSTOM1: return "_MUD"
			Mesh.ARRAY_CUSTOM2: return "_GRASS"
			Mesh.ARRAY_CUSTOM3: return "_SNOW"

	return ""

Supported attributes

• Mesh.ARRAY_TEX_UV (vec2)
• Mesh.ARRAY_TEX_UV2 (vec2)
• Mesh.ARRAY_COLOR (vec3, vec4)
• Mesh.ARRAY_CUSTOM# (scalar, vec2, vec3, vec4)

[fire]

I'm having a hard time understanding the extension. Can you link or write a proposal in https://github.com/godotengine/godot-proposals?

Something like: I have a game workflow that uses blender I want the vertex attributes to import from blender, but it needs this pr. I can use the attributes for a shader effect.

[huwpascoe]

godotengine/godot-proposals#10892

[huwpascoe]

Refactored and removed like a hundred duplicate lines of code.

_decode_accessor_as_floats();
_decode_accessor_as_ints();
_decode_accessor_as_vec2();
_decode_accessor_as_vec3();
_decode_accessor_as_color();
_decode_accessor_as_quaternion();
_decode_accessor_as_xform2d();
_decode_accessor_as_basis();
_decode_accessor_as_xform();

// VVV

_decode_accessor<T>();

Multi-element scalars are now decoded with _decode_accessor<T, N>()

array[Mesh::ARRAY_TANGENT] = _decode_accessor<float, 4>(p_state, a["TANGENT"], true, indices_mapping);

[aaronfranke]

Since this PR alters the accessor code, it will have to wait until after #94165 which also touches this code.

[Flynsarmy]

Since this PR alters the accessor code, it will have to wait until after #94165 which also touches this code.

PR in question was just merged so we should be good to continue here.

[fire]

@huwpascoe Many people think this is a good enhancement. Would you happen to have time to rebase it? <3

[huwpascoe]

@fire

Would it be better to keep as an extension or promote it to import options?
https://github.com/user-attachments/assets/52dc1357-7b32-49c2-a2ce-216343f69d60

There are trade-offs for each.

[fire]

I am trending towards promoting it to import options

[Flynsarmy]

Remember to take this PR out of draft if it's ready :)

[huwpascoe]

Remember to take this PR out of draft if it's ready :)

Don't worry! I haven't forgotten.

I am trending towards promoting it to import options

Right, I've determined that the UI approach is just too much of a mess for what is a technical feature. So I'll be moving forward with the original plan to add the method to DocumentExtension.