chameleon/Assets/Scripts/Editor/WebAssets/ModelImportUtil.cs

using System.Collections.Generic;
using UnityEditor;
using UnityEngine;

namespace Chameleon.Editor.WebAssets
{
    /// <summary>Shared helpers for imported 3D models (FBX etc.).</summary>
    public static class ModelImportUtil
    {
        /// <summary>
        /// Remaps every source material of an imported model to the given built materials.
        /// With a single set, all slots get that material; with multiple sets, the source
        /// material name is matched against the set names (substring, case-insensitive).
        /// </summary>
        public static void RemapMaterials(string modelAssetPath, List<(string setName, Material mat)> sets)
        {
            if (sets == null || sets.Count == 0)
                return;
            var importer = AssetImporter.GetAtPath(modelAssetPath) as ModelImporter;
            if (!importer)
            {
                Debug.LogWarning($"[PBR Import] No model importer at {modelAssetPath} — skipping material remap.");
                return;
            }

            // Source material names = the embedded materials Unity generated on import.
            var srcNames = new List<string>();
            foreach (var obj in AssetDatabase.LoadAllAssetsAtPath(modelAssetPath))
                if (obj is Material m)
                    srcNames.Add(m.name);

            if (srcNames.Count == 0)
            {
                Debug.LogWarning($"[PBR Import] {modelAssetPath} exposes no materials to remap.");
                return;
            }

            foreach (var name in srcNames)
            {
                var target = Pick(name, sets);
                if (!target)
                    continue;
                importer.AddRemap(new AssetImporter.SourceAssetIdentifier(typeof(Material), name), target);
            }
            importer.SaveAndReimport();
            Debug.Log($"[PBR Import] Remapped {srcNames.Count} material slot(s) on {modelAssetPath}.");
        }

        private static Material Pick(string srcName, List<(string setName, Material mat)> sets)
        {
            if (sets.Count == 1)
                return sets[0].mat;

            string s = srcName.ToLowerInvariant();
            foreach (var (setName, mat) in sets)
                if (!string.IsNullOrEmpty(setName) && s.Contains(setName.ToLowerInvariant()))
                    return mat;

            Debug.LogWarning($"[PBR Import] Material '{srcName}' matched no texture set — using '{sets[0].setName}'.");
            return sets[0].mat;
        }
    }
}