How to check if a file contains a mesh

At times it might be useful to check if a file contains a mesh. If it doesn’t, appropriate corrective action can be taken (such as fetching the mesh from the appropriate file before opening the mesh-less file).

The following code is an example of how this check can be done:

/*----------------------------------------------------------------------
                      open file if it contains a mesh
----------------------------------------------------------------------*/
//--------------------------------------------------------------------------------------------------
/// \brief open file if it contains a mesh
/// 
/// \param  datafun       Pointer to datafun object that has been initialized, but not open.
///                       If the file contains a mesh, the datafun object will be opened.
/// \param  filename      File name.
/// \param  libraryType   VdmTools library type.
/// 
/// \return
/// The function returns a boolean that is true if the file contained a mesh.
/// error flag, \a errorflag.
/// 
/// If the file contains a mesh, the file will be opened in the vdm_DataFun object and
/// the function will return true. Otherwise, the function will return false. This
/// functions sets the error handler to the default error handler (vut_ErrorHandler).
/// This functions assumes that the file is correct and that the only potential reason
/// for an error is the absence of a mesh in the file.
//--------------------------------------------------------------------------------------------------
bool openFileIfContainsMesh(vdm_DataFun* datafun, Vchar* filename, Vint libraryType)
{
    /*
      Setting a silent error handler function in order to avoid sending 
      the potential SYS_ERROR_OPERATION to standard output.
    */
    using ErrorHandler = void(*)(const char*, Vint, const char*);
    ErrorHandler silentErrorHandler = [](const char*, Vint, const char*) { ; };
    vut_ErrorSetHandler(silentErrorHandler);

    /*
      Trying to open the file.
    */
    vdm_DataFunOpen(datafun, 0, filename, libraryType);

    /*
      Going back to using the default error handler.
    */
    vut_ErrorSetHandler(vut_ErrorHandler);

    /*
      Checking if the file contained a mesh.
    */
    const Vint errorCode = vdm_DataFunError(datafun);
    bool containsMesh;
    if (errorCode == SYS_ERROR_OPERATION) {
        containsMesh = false;
        return containsMesh;
    }

    containsMesh = true;
    return containsMesh;
}

int main() { 

    Vint libraryType = SYS_NASTRAN_OUTPUT2;
    char filename[] = "meshlessfile.op2";

    vdm_DataFun* datafun = vdm_DataFunBegin();
    vdm_NASLib* naslib = vdm_NASLibBegin();
    vdm_NASLibDataFun(naslib, datafun);

    vdm_DataFunSetStatus(datafun, VDM_STATUS_OLD);

    const bool fileContainsMesh = openFileIfContainsMesh(datafun, filename, libraryType);

    if (fileContainsMesh) {
        /* Use your file */
    }
    else {
        /* Handle file without mesh */
    }

    vdm_DataFunClose(datafun);
    vdm_NASLibEnd(naslib);
    vdm_DataFunEnd(datafun);
    
    return 0;
}

KB Visual Kinematics

How to check if a file contains a mesh

Analytics