ModelTranslator: support external-texture FBX (disk AO fallback search, missing-texture graceful degradation)

Tools/ModelTranslator/README.md

@@ -36,7 +36,8 @@ out/tong/
 
 ## 转换规则
 
-- 贴图识别：沿材质 Principled BSDF 连线找 Base Color / Alpha / Normal / Metallic / Roughness；AO 按贴图名匹配（含 `ao`/`occlusion`/`ambient`）
+- 贴图识别：沿材质 Principled BSDF 连线找 Base Color / Alpha / Normal / Metallic / Roughness；内嵌与外置贴图（FBX 旁的松散文件）均支持
+- AO 按贴图名匹配（含 `ao`/`occlusion`/`ambient`）：先找材质内引用的贴图；FBX 未引用时自动搜索 FBX 同目录的图片文件，多候选优先与颜色贴图同前缀（`xxx_color.png` → `xxx_ao.png`）
 - 基础贴图 A 通道自动判定：**透明贴图 > 颜色贴图自带 alpha > AO 贴图 > 填白(255)**；判定为透明时 `.mat` 自动勾选 `Alpha As Transparency`（AlphaTest 裁剪）
 - 无对应贴图的通道用 Principled 常量值填充（会在日志中标注 `(常量)`）
 - 目标尺寸 = min(2048, 源贴图最大边)，所有贴图缩放到统一尺寸
@@ -48,6 +49,7 @@ out/tong/
 - 法线按 OpenGL 约定（+Y 向上）处理，不提供绿通道翻转
 - 不做多材质图集合并/UV 重排；每材质一套贴图
 - 动画/骨骼随 FBX 原样导出，不做处理
+- 外置贴图文件丢失时打警告并退化为常量，不中断转换
 
 ## 开发
 

Tools/ModelTranslator/bl_convert.py

@@ -36,10 +36,59 @@ def decode_sphere_map(enc01):
 # ---------------- 以下仅在 Blender 内执行 ----------------
 
 
+IMG_EXTS = ('.png', '.jpg', '.jpeg', '.tga', '.exr', '.bmp', '.tif', '.tiff')
+
+
 def _looks_like_ao(name):
     return bool(AO_NAME_RE.search(name))
 
 
+def _image_broken(img):
+    """外置贴图文件丢失/加载失败时，Blender 留下 0 尺寸空图。"""
+    return img.size[0] == 0 or img.size[1] == 0
+
+
+def _image_stem(img):
+    """贴图文件名（不含扩展名）；外置贴图优先用 filepath，比 img.name 可靠。"""
+    path = img.filepath if img.filepath else img.name
+    return os.path.splitext(os.path.basename(path))[0]
+
+
+def _find_ao_on_disk(src_dir, maps, warnings):
+    """材质未引用 AO 时，从 FBX 同目录按文件名兜底搜索（烘焙工具常只把 _ao.png 放旁边）。
+    多候选时优先与 basecolor 贴图同前缀（xxx_color.png -> xxx_ao.png）。"""
+    import bpy
+    try:
+        files = sorted(os.listdir(src_dir))
+    except OSError:
+        return None
+    cands = [f for f in files if f.lower().endswith(IMG_EXTS)
+             and _looks_like_ao(os.path.splitext(f)[0])]
+    if not cands:
+        return None
+    pick = None
+    if maps["basecolor"] and len(cands) > 1:
+        prefix = _image_stem(maps["basecolor"][0]).rsplit("_", 1)[0]
+        matched = [f for f in cands if f.startswith(prefix)]
+        if matched:
+            pick = matched[0]
+    if pick is None:
+        if len(cands) == 1:
+            pick = cands[0]
+        else:
+            warnings.append("同目录有多张疑似 AO 贴图无法确定归属，忽略：%s" % ", ".join(cands))
+            return None
+    try:
+        img = bpy.data.images.load(os.path.join(src_dir, pick), check_existing=True)
+    except RuntimeError as e:
+        warnings.append("AO 贴图 %s 加载失败：%s" % (pick, e))
+        return None
+    if _image_broken(img):
+        warnings.append("AO 贴图 %s 加载失败（0 尺寸）" % pick)
+        return None
+    return img
+
+
 def _image_pixels(img):
     """bpy Image -> float32 (h, w, 4)，原始值（不做色彩变换）。"""
     w, h = img.size
@@ -80,7 +129,7 @@ def _trace_image(socket, warnings, what):
     return None, None
 
 
-def _material_maps(mat, warnings):
+def _material_maps(mat, warnings, src_dir):
     """从材质 Principled BSDF 提取贴图与常量。"""
     maps = {"basecolor": None, "alpha": None, "normal": None,
             "metallic": None, "roughness": None, "ao": None}
@@ -99,6 +148,10 @@ def _material_maps(mat, warnings):
             return
         img, ch = _trace_image(sock, warnings, key)
         if img is not None:
+            if _image_broken(img):
+                warnings.append("%s 贴图 %s 加载失败（外置文件缺失？），改用常量"
+                                % (key, img.name))
+            else:
                 maps[key] = (img, ch)
 
     grab('Base Color', 'basecolor')
@@ -114,9 +167,13 @@ def _material_maps(mat, warnings):
     used = {m[0] for m in maps.values() if m}
     for n in mat.node_tree.nodes:
         if n.type == 'TEX_IMAGE' and n.image and n.image not in used \
-                and _looks_like_ao(n.image.name):
+                and not _image_broken(n.image) and _looks_like_ao(n.image.name):
             maps["ao"] = (n.image, None)
             break
+    if maps["ao"] is None:
+        img = _find_ao_on_disk(src_dir, maps, warnings)
+        if img is not None:
+            maps["ao"] = (img, None)
     return maps, consts
 
 
@@ -146,9 +203,9 @@ def _save_png(path, rgba):
     bpy.data.images.remove(img)
 
 
-def _convert_material(mat, model_name, outdir, max_size, used_snames):
+def _convert_material(mat, model_name, outdir, max_size, used_snames, src_dir):
     warnings = []
-    maps, consts = _material_maps(mat, warnings)
+    maps, consts = _material_maps(mat, warnings, src_dir)
     tw, th = _target_size(maps, max_size)
 
     # --- 基础贴图 ---
@@ -250,8 +307,9 @@ def main():
             if slot.material and slot.material not in used_mats:
                 used_mats.append(slot.material)
 
+    src_dir = os.path.dirname(os.path.abspath(src))
     used_snames = set()
-    results = [_convert_material(m, model_name, outdir, max_size, used_snames)
+    results = [_convert_material(m, model_name, outdir, max_size, used_snames, src_dir)
                for m in used_mats]
 
     _strip_textures()