And just in case anyone comes across this post looking to do the same thing, here's the working code. Note that it doesn't give any confirmation, it just exports the file.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Diagnostics;
using Autodesk.Revit.DB;
using Autodesk.Revit.DB.Architecture;
using Autodesk.Revit.UI;
using Autodesk.Revit.UI.Selection;
using Autodesk.Revit.ApplicationServices;
using Autodesk.Revit.Attributes;
[TransactionAttribute(TransactionMode.Manual)]
[RegenerationAttribute(RegenerationOption.Manual)]
public class Lab1PlaceGroup : IExternalCommand
{
//Set the path for the new text file
string myPath = @"c:\MyTest.txt";
public Result Execute(
ExternalCommandData commandData,
ref string message,
ElementSet elements)
{
//Get application and document objects
UIApplication uiApp = commandData.Application;
Document doc = uiApp.ActiveUIDocument.Document;
var collector = new FilteredElementCollector(doc).WhereElementIsNotElementType()
;
//If there's an existing file at the path, delete it.
if (File.Exists(myPath))
{
File.Delete(myPath);
}
//Create a new text file and fill it with lines of elementIDs and IFC GUIDs, with a space in between
using (StreamWriter myText = File.CreateText(myPath))
{
//Cycle through all elements in the scene, identify their element ID and GUID, then convert GUID into IFC GUID.
//Add both numbers to the text file with a space inbetween
foreach (Element x in collector)
{
int elemId = x.Id.IntegerValue;
Guid elemGuid = Autodesk.Revit.DB.ExportUtils.GetExportId(x.Document, x.Id);
String tempNum = IfcGuid.ToIfcGuid(elemGuid);
myText.WriteLine(elemId + " " + tempNum);
}
}
return Result.Succeeded;
}
//Found function to convert GUID's into IFC's 64-bit scheme, available at http://thebuildingcoder.typepad.com/blog/2010/06/ifc-guid-algorithm-in-c.html
public static class IfcGuid
{
/// <summary>
/// The replacement table
/// </summary>
private static readonly char[] base64Chars = new char[]
{ '0','1','2','3','4','5','6','7','8','9'
, 'A','B','C','D','E','F','G','H','I','J'
, 'K','L','M','N','O','P','Q','R','S','T'
, 'U','V','W','X','Y','Z','a','b','c','d'
, 'e','f','g','h','i','j','k','l','m','n'
, 'o','p','q','r','s','t','u','v','w','x'
, 'y','z','_','$' };
/// <summary>
/// Conversion of an integer into characters
/// with base 64 using the table base64Chars
/// </summary>
/// <param name="number">The number to convert</param>
/// <param name="result">The result char array to write to</param>
/// <param name="start">The position in the char array to start writing</param>
/// <param name="len">The length to write</param>
/// <returns></returns>
static void cv_to_64(uint number, ref char[] result, int start, int len)
{
uint act;
int iDigit, nDigits;
Debug.Assert(len <= 4);
act = number;
nDigits = len;
for (iDigit = 0; iDigit < nDigits; iDigit++)
{
result[start + len - iDigit - 1] = base64Chars[(int)(act % 64)];
act /= 64;
}
Debug.Assert(act == 0, "Logic failed, act was not null: " + act.ToString());
return;
}
public static string ToIfcGuid(Guid guid)
{
uint[] num = new uint[6];
char[] str = new char[22];
int i, n;
byte[] b = guid.ToByteArray();
// Creation of six 32 Bit integers from the components of the GUID structure
num[0] = (uint)(BitConverter.ToUInt32(b, 0) / 16777216);
num[1] = (uint)(BitConverter.ToUInt32(b, 0) % 16777216);
num[2] = (uint)(BitConverter.ToUInt16(b, 4) * 256 + BitConverter.ToInt16(b, 6) / 256);
num[3] = (uint)((BitConverter.ToUInt16(b, 6) % 256) * 65536 + b[8] * 256 + b[9]);
num[4] = (uint)(b[10] * 65536 + b[11] * 256 + b[12]);
num[5] = (uint)(b[13] * 65536 + b[14] * 256 + b[15]);
// Conversion of the numbers into a system using a base of 64
n = 2;
int pos = 0;
for (i = 0; i < 6; i++)
{
cv_to_64(num[i], ref str, pos, n);
pos += n; n = 4;
}
return new String(str);
}
}
}
