from OCC.Core.STEPControl import STEPControl_Reader
from OCC.Core.IFSelect import IFSelect_RetDone
from OCC.Core.BRepMesh import BRepMesh_IncrementalMesh
from OCC.Core.StlAPI import StlAPI_Writer
import time
import argparse  # 命令行参数解析

def step2lightweight_stl(mesh_precision, input_step, output_stl):
    """STEP转轻量化STL，纯后台处理，无显示，体积暴减"""
    start_total = time.time()
    # 1. 读取STEP文件
    print(f"【1/3】读取STEP文件：{input_step}")
    step_reader = STEPControl_Reader()
    if step_reader.ReadFile(input_step) != IFSelect_RetDone:
        raise Exception("STEP文件读取失败！检查路径/文件完整性")
    step_reader.TransferRoots()
    shape = step_reader.OneShape()
    print(f"【1/3】读取完成，耗时：{time.time()-start_total:.2f}秒")

    # 2. 核心：网格离散化
    print(f"【2/3】网格离散化（精度{mesh_precision}mm），开始轻量化...")
    mesh = BRepMesh_IncrementalMesh(shape, mesh_precision, False)
    mesh.Perform()
    if not mesh.IsDone():
        raise Exception("网格离散化失败！")
    print(f"【2/3】轻量化完成，耗时：{time.time()-start_total:.2f}秒")

    # 3. 保存为STL
    print(f"【3/3】保存轻量化STL：{output_stl}")
    stl_writer = StlAPI_Writer()
    stl_writer.Write(shape, output_stl)

    total_time = time.time() - start_total
    print(f"✅ 转换完成！总耗时：{total_time:.2f}秒")
    print(f"💡 提示：STL文件可直接用FreeCAD/MeshLab/3D Viewer打开")

if __name__ == "__main__":
    # ========== 命令行参数定义 ==========
    parser = argparse.ArgumentParser(description="STEP 转 轻量化 STL (命令行args版)")
    parser.add_argument("--precision", "-p", type=float, default=1.0, help="网格精度 MESH_PRECISION (mm)，越大文件越小")
    parser.add_argument("--input", "-i", type=str,   default="High_Speed_Data/CAD/11.step", help="输入STEP文件路径 INPUT_STEP_PATH")
    parser.add_argument("--output", "-o", type=str,  default="High_Speed_Data/Mesh/11.stl", help="输出STL文件路径 OUTPUT_STL_PATH")
    
    # 解析参数
    args = parser.parse_args()

    # 调用转换函数
    try:
        step2lightweight_stl(
            mesh_precision=args.precision,
            input_step=args.input,
            output_stl=args.output
        )
    except Exception as e:
        print(f"❌ 处理失败：{str(e)}")