Как мне написать функцию read and write for ASCII STL file?

  //  
    #include "STLParser.h" 
    #include <vector> 
    #include <algorithm> 
    #include <iostream> 
    #include <fstream> 

     //Parse section
//read fuction
    TriangleSoup STLParser::read(const std::string& filename) 
    { 
     std::ifstream stlfilereader; 
     
     stlfilereader.open(filename); 
     
      
     if (!stlfilereader) { 
     
       
      std::cout << "Not found"; 
     } 
      
     
     std::string ignore; 
     stlfilereader >> ignore >> ignore;//sorry 
     
     while (true) { 
     
      stlfilereader >> ignore >> ignore; // ignore our normal 
     
      float normal[3]; 
     
      stlfilereader >> normal[0] >> normal[1] >> normal[2]; // read and save data after that  
     
      stlfilereader >> ignore >> ignore; // ignore outer loop 
     
      for (size_t i = 0; i < 3; ++i) // read the three vertices and our face 
      { 
     
     
     
     
     
      } 
     
      stlfilereader >> ignore >> ignore; // endloop // endfacet 
     } 
     stlfilereader.close(); 
     return TriangleSoup(); 
    } 
     //write fuction
    void STLParser::write(const TriangleSoup& triangleSoup, const std::string& filename) 
    { 
     
         
     
    }