/// <summary>
    /// Utility method for getting the intersection between two lines.
    /// </summary>
    /// <param name="line1">The first line.</param>
    /// <param name="line2">The second line.</param>
    /// <returns>The intersection point.</returns>
    /// <exception cref="InvalidOperationException">Thrown when an intersection can't be found.</exception>
    private Autodesk.Revit.DB.XYZ GetIntersection(Line line1, Line line2)
    {
        IntersectionResultArray results;//交点数组
        Autodesk.Revit.DB.SetComparisonResult result = line1.Intersect(line2, out results);

if (result != Autodesk.Revit.DB.SetComparisonResult.Overlap)//重叠，没有重叠就是平行
            throw new InvalidOperationException("Input lines did not intersect.");

if (results == null || results.Size != 1)//没有交点或者交点不是1个
            throw new InvalidOperationException("Could not extract intersection point for lines.");

IntersectionResult iResult = results.get_Item(0);//取得交点
        Autodesk.Revit.DB.XYZ intersectionPoint = iResult.XYZPoint;//取得交点坐标

return intersectionPoint;
    }

//[Transaction(TransactionMode.Automatic)]
[Transaction(TransactionMode.Manual)]
[Regeneration(RegenerationOption.Manual)]
//[Journaling(JournalingMode.NoCommandData)]
public class NewPipeCommand : IExternalCommand
{
    public Result Execute(ExternalCommandData commandData, ref string messages, ElementSet elements)
    {
        UIApplication uiApp = commandData.Application;
        Document doc = uiApp.ActiveUIDocument.Document;
        //CreateNewPipe(doc);

//线段交点
        XYZ xyz1 = new XYZ(0, 0, 0);
        XYZ xyz2 = new XYZ(100, 0, 0);
        Line line1 = Line.get_Bound(xyz1, xyz2);

XYZ xyz3 = new XYZ(-10, -10, 0);
        XYZ xyz4 = new XYZ(100, 100, 0);
        Line line2 = Line.get_Bound(xyz3, xyz4);
        XYZ xyz = null;
        //XYZ xyz = IntersectionPoint(line1, line2);

//MessageBox.Show(xyz.X + "," + xyz.Y + "," + xyz.Z);

//直线交点，按说应该相交在(0,0,0)但却是(2.8,0,0)
        Curve curve1 = Line.get_Bound(xyz1, xyz2) as Curve;
        Curve curve2 = Line.get_Bound(xyz3, xyz4) as Curve;
        curve1.MakeUnbound();//unbound绑定
        curve2.MakeUnbound();
        xyz = IntersectionPoint(curve1, curve2);

MessageBox.Show(xyz.X + "," + xyz.Y + "," + xyz.Z);

return Result.Succeeded;
    }
    //取得两条线段的交点，直线延长线上的相交不算。
    public XYZ IntersectionPoint(Line line1, Line line2)
    {
        IntersectionResultArray intersectionR = new IntersectionResultArray();
        SetComparisonResult comparisonR;
        comparisonR = line1.Intersect(line2, out intersectionR);
        XYZ intersectionResult = null;
        if (SetComparisonResult.Disjoint != comparisonR)//Disjoint不交
        {
            if (!intersectionR.IsEmpty)//两条直线如果重复为一条直线，这里也为空
            {
                intersectionResult = intersectionR.get_Item(0).XYZPoint;
            }
        }
        return intersectionResult;
    }
    //取得两条直线的交点
    public XYZ IntersectionPoint(Curve curve1, Curve curve2)
    {
        IntersectionResultArray intersectionR = new IntersectionResultArray();
        SetComparisonResult comparisonR;
        comparisonR = curve1.Intersect(curve2, out intersectionR);
        XYZ intersectionResult = null;
        if (SetComparisonResult.Disjoint != comparisonR)//Disjoint不交
        {
            if (!intersectionR.IsEmpty)//两条直线如果重复为一条直线，这里也为空
            {
                intersectionResult = intersectionR.get_Item(0).XYZPoint;
            }
        }
        return intersectionResult;
    }

public Pipe CreateNewPipe(Document document)
    {
        FilteredElementCollector collector = new FilteredElementCollector(document);
        collector.OfClass(typeof(PipeType));
        PipeType pipeType = collector.FirstElement() as PipeType;

Pipe pipe = null;
        if (null != pipeType)
        {
            //create pipe between 2 points
            XYZ p1 = new XYZ(0, 0, 0);
            XYZ p2 = new XYZ(10, 0, 0);
            pipe = document.Create.NewPipe(p1, p2, pipeType);
        }
        return pipe;
    }
}