ModelTranslator: add QR quad remesh decimate backend with collapse fallback

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Tools/ModelTranslator/bl_decimate.py

@@ -6,6 +6,10 @@ import sys
 
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
 
+import qr_bridge
+
+QR_POLL_INTERVAL = 0.3   # progress.txt 轮询间隔（秒）
+
 TOLERANCE = 0.03    # 面数相对误差容忍
 MAX_RETRY = 2       # ratio 修正轮数上限
 
@@ -112,6 +116,92 @@ def _decimate(obj, ratio):
     _apply_modifier(obj, mod)
 
 
+def _remesh_quad(obj, target_tris, warnings):
+    """Quad Remesher 重拓扑 obj（headless 直调 xremesh.exe，绕开 modal 操作符）。
+    成功返回 True，并把导回的 quad 网格设为新 active object（原 obj 已删）；
+    任何失败记 warning 返回 False，交上层回退 collapse。"""
+    import bpy
+    import subprocess
+    import tempfile
+    import time
+    engine = qr_bridge.find_qr_engine()
+    if not engine:
+        warnings.append("未找到 QuadRemesher 引擎(xremesh.exe)，回退 collapse")
+        return False
+    work = os.path.join(tempfile.gettempdir(), "mt_qr")
+    os.makedirs(work, exist_ok=True)
+    in_fbx = os.path.join(work, "inputMesh.fbx").replace("\\", "/")
+    out_fbx = os.path.join(work, "retopo.fbx").replace("\\", "/")
+    prog = os.path.join(work, "progress.txt").replace("\\", "/")
+    settings = os.path.join(work, "RetopoSettings.txt")
+    for f in (out_fbx, prog):
+        if os.path.isfile(f):
+            os.remove(f)
+    try:
+        bpy.ops.object.select_all(action='DESELECT')
+        obj.select_set(True)
+        bpy.context.view_layer.objects.active = obj
+        bpy.ops.export_scene.fbx(filepath=in_fbx, use_selection=True)
+        target_quads = qr_bridge.tris_to_target_quads(target_tris)
+        with open(settings, "w") as fp:
+            fp.write(qr_bridge.build_settings(in_fbx, out_fbx, prog, target_quads))
+        proc = subprocess.Popen([engine, "-s", settings])
+    except Exception as e:
+        warnings.append("QR 启动失败(%s)，回退 collapse" % e)
+        return False
+
+    t0 = time.time()
+    state = "running"
+    while True:
+        try:
+            with open(prog) as fp:
+                state, msg = qr_bridge.parse_progress(fp.read())
+        except IOError:
+            state, msg = "running", ""
+        if state == "success":
+            break
+        if state == "error":
+            warnings.append("QR 重拓扑失败(%s)，回退 collapse" % msg)
+            return False
+        if proc.poll() is not None:
+            # 进程已退出：给 progress/输出一点落地时间后再判一次
+            time.sleep(QR_POLL_INTERVAL)
+            try:
+                with open(prog) as fp:
+                    state, _ = qr_bridge.parse_progress(fp.read())
+            except IOError:
+                state = "running"
+            break
+        if time.time() - t0 > qr_bridge.QR_TIMEOUT:
+            proc.kill()
+            warnings.append("QR 超时(%ds)，回退 collapse" % int(qr_bridge.QR_TIMEOUT))
+            return False
+        time.sleep(QR_POLL_INTERVAL)
+
+    if state != "success" or not (
+            os.path.isfile(out_fbx) and os.path.getsize(out_fbx) > 0):
+        warnings.append("QR 无有效输出，回退 collapse")
+        return False
+
+    try:
+        before = set(bpy.data.objects)
+        bpy.ops.import_scene.fbx(filepath=out_fbx)
+        new = [o for o in bpy.data.objects
+               if o not in before and o.type == 'MESH']
+        if not new:
+            warnings.append("QR 导回无 mesh，回退 collapse")
+            return False
+        retopo = new[0]
+        bpy.data.objects.remove(obj, do_unlink=True)
+        bpy.ops.object.select_all(action='DESELECT')
+        retopo.select_set(True)
+        bpy.context.view_layer.objects.active = retopo
+        return True
+    except Exception as e:
+        warnings.append("QR 导回失败(%s)，回退 collapse" % e)
+        return False
+
+
 def _clean_mesh(obj, warnings):
     """减面前清理：按局部包围盒对角线相对焊接重合点 + 去退化面，给 collapse 更干净的流形，
     减少被迫加的 seam。各步失败降级不中断。"""
@@ -392,6 +482,7 @@ def main():
     src, out_fbx, target = argv[0], argv[1], int(argv[2])
     unwrap_mode = argv[3] if len(argv) > 3 else "seam"
     overlap_tol = float(argv[4]) if len(argv) > 4 and argv[4] else UV_OVERLAP_TOL
+    reducer_arg = argv[5] if len(argv) > 5 else "collapse"
     warnings = []
 
     bpy.ops.wm.read_factory_settings(use_empty=True)
@@ -408,8 +499,20 @@ def main():
 
     _clean_mesh(obj, warnings)
     _triangulate(obj)
-    orig = len(obj.data.polygons)
+    orig = len(obj.data.polygons)   # 高模三角面数（tris_before）
     cur = orig
+    used_reducer = "collapse"
+    did_quad = False
+    if reducer_arg == "quad":
+        if _remesh_quad(obj, target, warnings):
+            obj = bpy.context.view_layer.objects.active   # QR 导回的 quad 对象
+            _triangulate(obj)                             # 三角化供导出/计数
+            cur = len(obj.data.polygons)
+            used_reducer = "quad"
+            did_quad = True
+        else:
+            used_reducer = "quad->collapse"
+    if not did_quad:
         if cur <= target:
             warnings.append("当前 %d 面 <= 目标 %d，跳过减面" % (cur, target))
         else:
@@ -445,6 +548,7 @@ def main():
     print("MT_SUMMARY " + json.dumps(
         {"src": os.path.basename(src), "fbx": os.path.basename(out_fbx),
          "tris_before": orig, "tris_after": cur, "target": target,
+         "reducer": used_reducer,
          "uv": uv_info,
          "uv_preview": uv_preview,
          "uv_polys": uv_polys_json if uv_preview else None,