importer.gd

@tool
extends EditorScenePostImport

var MATERIAL_REPLACEMENTS := {}
var TEXTURES := {}

func _init():
	setup_textures()
	setup_materials()

func setup_textures():
	TEXTURES["Material_001"] = load("res://addons/gltf_material_swapper/textures/material_001.png")
	TEXTURES["Material_002"] = load("res://addons/gltf_material_swapper/textures/material_002.png")
	TEXTURES["Metallic"] = load("res://addons/gltf_material_swapper/textures/metallic.png")

func setup_materials():
	MATERIAL_REPLACEMENTS["Material_001"] = StandardMaterial3D.new()
	MATERIAL_REPLACEMENTS["Material_001"].albedo_color = Color(1, 0, 0)
	MATERIAL_REPLACEMENTS["Material_001"].albedo_texture = TEXTURES.get("Material_001")
	
	MATERIAL_REPLACEMENTS["Material_002"] = StandardMaterial3D.new()
	MATERIAL_REPLACEMENTS["Material_002"].albedo_color = Color(0, 1, 0)
	MATERIAL_REPLACEMENTS["Material_002"].albedo_texture = TEXTURES.get("Material_002")
	
	MATERIAL_REPLACEMENTS["Metallic"] = StandardMaterial3D.new()
	MATERIAL_REPLACEMENTS["Metallic"].metallic = 1.0
	MATERIAL_REPLACEMENTS["Metallic"].metallic_texture = TEXTURES.get("Metallic")

func _post_import(scene: Node) -> Object:
	if not get_source_file().ends_with(".gltf") and not get_source_file().ends_with(".glb"):
		return scene  # Skip non-GLTF imports
	
	var meta := get_import_metadata()
	if meta.has("materials_swapped") and meta["materials_swapped"] == true:
		return scene  # Skip if already processed
	
	swap_materials(scene)
	meta["materials_swapped"] = true
	return scene

func swap_materials(node: Node):
	if node is MeshInstance3D:
		var mesh_instance := node as MeshInstance3D
		for i in range(mesh_instance.get_surface_material_count()):
			var material = mesh_instance.get_surface_material(i)
			if material:
				var material_name = material.resource_name
				if material_name in MATERIAL_REPLACEMENTS and mesh_instance.get_surface_material(i) != MATERIAL_REPLACEMENTS[material_name]:
					mesh_instance.set_surface_material(i, MATERIAL_REPLACEMENTS[material_name])
	
	for child in node.get_children():
		swap_materials(child)

plugin.gd

@tool
extends EditorPlugin

var gltf_post_import_plugin

func _enter_tree():
	gltf_post_import_plugin = load("res://addons/gltf_material_swapper/importer.gd").new()
	add_scene_post_import_plugin(gltf_post_import_plugin)

func _exit_tree():
	if gltf_post_import_plugin:
		remove_scene_post_import_plugin(gltf_post_import_plugin)
		gltf_post_import_plugin = null