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# OCCT 转换服务
把 STEP 文件转成 glTF/GLB供网页 3D 轻量化预览用。**只做转换,不做参数化建模**(升级 2 已决策不做)。
## 依赖
- Python 3.x
- `OCP`OpenCASCADE Python 绑定,本机已验证可用)
## 启动
```
start-service.bat
```
或命令行:`python occt_service.py`(端口默认 8090可用环境变量 `OCCT_PORT` 改)。
## 接口
| 接口 | 方法 | 说明 |
|---|---|---|
| `/health` | GET | 存活探测 → `{"ok":true,"port":8090}` |
| `/convert` | POST | 请求体 = STEP 文件二进制query `deflection=0.5`(弦偏差,越大越轻)→ 返回 GLB 二进制 |
## 调用示例
```bash
curl -X POST --data-binary @model.step "http://localhost:8090/convert?deflection=0.5" -o model.glb
```
## 设计说明
- 零新依赖HTTP 用标准库 `http.server`,几何用 OCP。
- 单线程OCP 非线程安全,避免并发崩溃。
- 临时文件用完即删,不落盘。
- deflection 默认 0.5mm(屏幕预览够用,体积小);要更精细可调小到 0.1,要更小可调大到 2.0。
## 与主项目的关系
- 这是升级 1网页 3D 轻量化)的转换后端,独立进程、独立端口,不依赖 NX。
- 生产部署时可放服务器(服务器无需装 NXOCP 是纯 Python 库)。

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# -*- coding: utf-8 -*-
"""
批量转换:把 catalog\step\ 下所有 STEP 转成 glTF/GLB网页 3D 轻量化用)。
用法:
python batch-convert-glb.py <step目录> <gltf输出目录> [deflection]
说明:
- 走本地 OCCT 服务的 /convert 接口(需先启动 occt_service.py
- 同名 .step → .glb断点续传已存在且非空的 .glb 跳过)
- 单线程、逐文件,避免给服务造成压力
- 默认 deflection=0.5(屏幕预览够用)
"""
import os
import sys
import time
import urllib.request
OCCT_URL = os.environ.get("OCCT_URL", "http://localhost:8090")
def convert_one(step_path, glb_path, deflection):
with open(step_path, "rb") as f:
data = f.read()
req = urllib.request.Request(
"%s/convert?deflection=%s" % (OCCT_URL, deflection),
data=data, method="POST",
headers={"Content-Type": "application/octet-stream"},
)
resp = urllib.request.urlopen(req, timeout=120)
out = resp.read()
if not out or out[:4] != b"glTF":
raise RuntimeError("转换失败(非法 glb): %s" % step_path)
# 原子写:先写临时再改名
tmp = glb_path + ".tmp"
with open(tmp, "wb") as f:
f.write(out)
os.replace(tmp, glb_path)
def main():
if len(sys.argv) < 3:
print("用法: python batch-convert-glb.py <step目录> <gltf输出目录> [deflection]")
sys.exit(1)
step_dir = sys.argv[1]
out_dir = sys.argv[2]
deflection = float(sys.argv[3]) if len(sys.argv) > 3 else 0.5
os.makedirs(out_dir, exist_ok=True)
steps = []
for root, _, files in os.walk(step_dir):
for fn in files:
if fn.lower().endswith((".step", ".stp")):
steps.append(os.path.join(root, fn))
steps.sort()
ok = 0
skip = 0
fail = 0
t0 = time.time()
for i, sp in enumerate(steps):
base = os.path.splitext(os.path.basename(sp))[0]
gp = os.path.join(out_dir, base + ".glb")
if os.path.exists(gp) and os.path.getsize(gp) > 0:
skip += 1
continue
try:
convert_one(sp, gp, deflection)
ok += 1
if (ok + skip) % 50 == 0:
print("[%d/%d] ok=%d skip=%d fail=%d %.1fs" % (i + 1, len(steps), ok, skip, fail, time.time() - t0))
except Exception as e:
fail += 1
print("[FAIL] %s: %s" % (os.path.basename(sp), e))
print("完成: 总 %d, 转换 %d, 跳过 %d, 失败 %d, 耗时 %.1fs" % (len(steps), ok, skip, fail, time.time() - t0))
if fail:
sys.exit(2)
if __name__ == "__main__":
main()

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# -*- 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 OCPOpenCASCADE 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 HTTPServerOCP 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
# XCAFglTF 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()

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@echo off
cd /d "%~dp0"
echo Starting OCCT conversion service on port 8090 ...
python occt_service.py
pause