求空间直线与平面的交点

[CommandMethod("MyGroup", "Test01", "Test01Local", CommandFlags.Modal)]
public void MyCommand_Test01() // This method can have any name
{
    Point3d p1 = new Point3d(2, 3, 4);
    Point3d p2 = new Point3d(3, 4, 5);
    Vector3d v1 = new Vector3d(1, 2, 3);
    Vector3d v2 = new Vector3d(2, 3, 4);

    Line line = new Line(p1, p1 + v1);
    Circle circle = new Circle(p2, v2, 5);
    var pt = GetInt(p1, v1, p2, v2);
    Application.DocumentManager.MdiActiveDocument.Editor.WriteMessage(pt.ToString());
    DBPoint dBPoint = new DBPoint(pt);
    using (Transaction tr = Application.DocumentManager.MdiActiveDocument.TransactionManager.StartTransaction())
    {
        BlockTable bt = (BlockTable)tr.GetObject(Application.DocumentManager.MdiActiveDocument.Database.BlockTableId, OpenMode.ForRead, false);
        BlockTableRecord btr = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite, false);

        btr.AppendEntity(line);
        btr.AppendEntity(circle);
        btr.AppendEntity(dBPoint);
        tr.AddNewlyCreatedDBObject(line, true);
        tr.AddNewlyCreatedDBObject(circle, true);
        tr.AddNewlyCreatedDBObject(dBPoint, true);
        tr.Commit();
    }
}

/// <summary>
/// 求直线与平面的交点
/// https://www.jianshu.com/p/4b630c11f9f5
/// </summary>
/// <param name="lP">直线上的一点</param>
/// <param name="lD">直线方向</param>
/// <param name="pP">平面上一点</param>
/// <param name="pD">平面上方向</param>
/// <returns交点</returns>
static Point3d GetInt(Point3d lP, Vector3d lD, Point3d pP, Vector3d pD)
{
    if (lD.X * pD.X + lD.Y * pD.Y + lD.Z * pD.Z == 0)
    {
        //方向向量与平面平行，没有交点，返回原点应该不合适，需要注意
        return Point3d.Origin;
    }
    double m = ((pP.X - lP.X) * pD.X +
               (pP.Y - lP.Y) * pD.Y +
               (pP.Z - lP.Z) * pD.Z) /
              (pD.X * lD.X + pD.Y * lD.Y + pD.Z * lD.Z);
    return new Point3d(lP.X + lD.X * m, lP.Y + lD.Y * m, lP.Z + lD.Z * m);
}