新增: OCCT 转换服务(STEP→glTF 轻量化后端, 8090 端口, 零新依赖)

occt-service/occt_service.py

@@ -0,0 +1,165 @@
+# -*- coding: utf-8 -*-
+"""
+OCCT 转换服务（常驻 HTTP，默认端口 8090）
+
+只做一件事：读 STEP 文件 → 三角化 → 导出 glTF/GLB（网页 3D 轻量化用）。
+零新依赖：HTTP 用标准库 http.server，几何内核用 OCP（OpenCASCADE Python 绑定）。
+
+接口：
+  GET  /health              存活探测 → {"ok":true,"port":8090}
+  POST /convert             请求体 = STEP 文件二进制（raw body），
+                            query 参数 deflection=弦偏差(默认 0.5) → 返回 GLB 二进制
+                            失败返回 JSON {"error": "..."}
+
+说明：
+  - 单线程 HTTPServer：OCP 是 C++ 绑定、非线程安全，避免并发导致崩溃。
+  - 每次转换写临时文件，转换完清理。
+  - 本服务只做「STEP→glTF」转换，不做参数化建模（升级2 已决策不做）。
+"""
+import os
+import sys
+import time
+import tempfile
+from http.server import HTTPServer, BaseHTTPRequestHandler
+from urllib.parse import urlparse, parse_qs
+
+from OCP.STEPControl import STEPControl_Reader
+from OCP.BRepMesh import BRepMesh_IncrementalMesh
+from OCP.IFSelect import IFSelect_RetDone
+# XCAF（glTF 导出用）
+from OCP.XCAFApp import XCAFApp_Application
+from OCP.TCollection import TCollection_ExtendedString
+from OCP.TDocStd import TDocStd_Document
+from OCP.XCAFDoc import XCAFDoc_DocumentTool, XCAFDoc_ShapeTool
+from OCP.RWGltf import RWGltf_CafWriter
+from OCP.TColStd import TColStd_IndexedDataMapOfStringString
+from OCP.Message import Message_ProgressRange
+
+PORT = int(os.environ.get("OCCT_PORT", "8090"))
+
+
+def read_step(path):
+    """读 STEP 文件 → TopoDS_Shape"""
+    reader = STEPControl_Reader()
+    status = reader.ReadFile(path)
+    if status != IFSelect_RetDone:
+        raise RuntimeError("STEP 读取失败 status=%s" % status)
+    reader.TransferRoots()
+    return reader.OneShape()
+
+
+def tessellate(shape, deflection):
+    """三角化（弦偏差 deflection 控制精度/体积平衡）"""
+    mesh = BRepMesh_IncrementalMesh(shape, deflection, False, 0.5, True)
+    mesh.Perform()
+    return shape
+
+
+def export_glb(shape, out_path, deflection=0.5):
+    """shape → 二进制 GLB（经 XCAF 文档承载）"""
+    tessellate(shape, deflection)
+    app = XCAFApp_Application.GetApplication_s()
+    doc = TDocStd_Document(TCollection_ExtendedString("XmlOcaf"))
+    app.InitDocument(doc)
+    st = XCAFDoc_DocumentTool.ShapeTool_s(doc.Main())
+    lbl = st.NewShape()
+    st.SetShape(lbl, shape)
+    w = RWGltf_CafWriter(out_path, True)  # True = 二进制 GLB
+    info = TColStd_IndexedDataMapOfStringString()
+    prog = Message_ProgressRange()
+    return w.Perform(doc, info, prog)
+
+
+class Handler(BaseHTTPRequestHandler):
+    server_version = "occt-service/1.0"
+
+    def log_message(self, fmt, *args):
+        sys.stderr.write("[%s] %s\n" % (time.strftime("%H:%M:%S"), fmt % args))
+
+    def _json(self, code, obj):
+        import json
+        body = json.dumps(obj).encode("utf-8")
+        self.send_response(code)
+        self.send_header("Content-Type", "application/json; charset=utf-8")
+        self.send_header("Content-Length", str(len(body)))
+        self.end_headers()
+        self.wfile.write(body)
+
+    def _send_glb(self, path):
+        size = os.path.getsize(path)
+        self.send_response(200)
+        self.send_header("Content-Type", "model/gltf-binary")
+        self.send_header("Content-Disposition", 'attachment; filename="model.glb"')
+        self.send_header("Content-Length", str(size))
+        self.end_headers()
+        with open(path, "rb") as f:
+            while True:
+                chunk = f.read(65536)
+                if not chunk:
+                    break
+                self.wfile.write(chunk)
+
+    def do_GET(self):
+        path = urlparse(self.path).path
+        if path == "/health":
+            self._json(200, {"ok": True, "port": PORT})
+        else:
+            self._json(404, {"error": "not_found"})
+
+    def do_POST(self):
+        parsed = urlparse(self.path)
+        if parsed.path != "/convert":
+            self._json(404, {"error": "not_found"})
+            return
+        qs = parse_qs(parsed.query)
+        deflection = 0.5
+        if "deflection" in qs:
+            try:
+                deflection = float(qs["deflection"][0])
+                deflection = max(0.05, min(10.0, deflection))
+            except ValueError:
+                pass
+        # 读 raw body（整个请求体 = STEP 文件）
+        length = int(self.headers.get("Content-Length", "0"))
+        if length == 0:
+            self._json(400, {"error": "empty_body"})
+            return
+        data = self.rfile.read(length)
+
+        tmp_step = tempfile.mktemp(suffix=".step")
+        tmp_glb = tempfile.mktemp(suffix=".glb")
+        try:
+            with open(tmp_step, "wb") as f:
+                f.write(data)
+            t0 = time.time()
+            shape = read_step(tmp_step)
+            ok = export_glb(shape, tmp_glb, deflection)
+            if not ok:
+                self._json(500, {"error": "gltf_export_failed"})
+                return
+            elapsed = time.time() - t0
+            self.log_message("convert OK %.2fs deflection=%.2f size=%d", elapsed, deflection, os.path.getsize(tmp_glb))
+            self._send_glb(tmp_glb)
+        except Exception as e:
+            self._json(500, {"error": str(e)[:200]})
+        finally:
+            for p in (tmp_step, tmp_glb):
+                try:
+                    if os.path.exists(p):
+                        os.remove(p)
+                except OSError:
+                    pass
+
+
+def main():
+    server = HTTPServer(("0.0.0.0", PORT), Handler)
+    sys.stderr.write("OCCT 转换服务已启动: http://0.0.0.0:%d  (/convert, /health)\n" % PORT)
+    sys.stderr.flush()
+    try:
+        server.serve_forever()
+    except KeyboardInterrupt:
+        sys.stderr.write("\n服务已停止\n")
+
+
+if __name__ == "__main__":
+    main()