CGAL users discussion list

[StevenChen06 <>]

It happens on CGAL3.8, Windows 7 32 bit. For some kind of input data and some
kind of programming language, the host program will definitely crash if it
call the constraint triangulation procedure as a DLL function.
 
For instance, Let's see a test DLL library:
  
#include <CGAL/Exact_predicates_inexact_constructions_kernel.h>
#include <CGAL/Constrained_triangulation_2.h>
#include <fstream>

typedef CGAL::Exact_predicates_inexact_constructions_kernel K;
typedef CGAL::Triangulation_vertex_base_2<K> Vb;
typedef CGAL::Constrained_triangulation_face_base_2<K> Fb;
typedef CGAL::Triangulation_data_structure_2&lt;Vb,Fb&gt; TDS;
typedef CGAL::Exact_predicates_tag Itag;
typedef CGAL::Constrained_triangulation_2&lt;K, TDS, Itag&gt; CT;
typedef CT::Point Point;

extern "C" int __declspec(dllexport)
TestTriangulate()
{
        //TEST CODE
        std::fstream file;
        file.open("E:\\TriDebug.md", std::ios::binary|std::ios::in);
        assert(file.good());
        int seg_cnt;
        file.read((char*)&seg_cnt, 4);
        CT ct;
        for(int i = 0; i < seg_cnt; ++i)
        {
                double sx, sy, ex, ey;
                file.read((char*)&sx, 8);
                file.read((char*)&sy, 8);
                file.read((char*)&ex, 8);
                file.read((char*)&ey, 8);
                ct.insert_constraint(Point(sx, sy), Point(ex, ey));
        }
        file.close();
        assert(ct.is_valid());
        int face_cnt = ct.number_of_faces();
        return face_cnt;
}

It reads constraint segments from file, adds them to CT, then checks the
validation of triangulation. very simple.

Next is the c++ host program:

#include <iostream>
#include <windows.h>
using namespace std;

typedef int (_stdcall *TestFunc)();
int main()
{
  HINSTANCE hDllInst = LoadLibrary("NewTri.dll");
  if(hDllInst)
  {
          TestFunc testf;
          testf = (TestFunc)GetProcAddress(hDllInst, "TestTriangulate");
          if(testf)
          {
                  cout << testf() << endl;
          }
          FreeLibrary(hDllInst);
  }
  system("pause");
  return 0;
}

Every time it runs good. No crash. No memory problem.

However, Let's try delphi 7:

program test_dll_mem_delphi7;

{$APPTYPE CONSOLE}

uses
  SysUtils;

  function TestTriangulate: integer; cdecl; external 'NewTri.dll' name
'TestTriangulate';

var
  cnt: Integer;
begin
  cnt := TestTriangulate;
  Writeln(cnt);
end.

it will definitely crash. By debug mode the compiler reports a stackoverflow
exception.

I also tested it by some other programming language and found:
FOR c++(vs2008), c#(vs2008), python(2.7), It runs smoothly and no exception.
FOR Delphi7, DelphiXE, ruby(1.9.2-p0), It always crashes.

I uploaded the dll library and test data. 
http://cgal-discuss.949826.n4.nabble.com/file/n3838960/TriDebug.zip
TriDebug.zip 
Hope some one could help me, thanks!
BTW, I have another question. What kind of input data does the constraint
triangulation Algorithm favor? What kind of input data should I get rid of?
Because all the crashes only happen under a small number of input data.  

 
  

--
View this message in context: 
http://cgal-discuss.949826.n4.nabble.com/Fatal-error-on-calling-the-constraint-triangulation-as-a-DLL-function-tp3838960p3838960.html
Sent from the cgal-discuss mailing list archive at Nabble.com.