请用teklaopenapi写一段选择梁的代码，需求如下在模型中选中的代码中把起止点向量为正X的坐标的选中，反之不选中

以下是使用Tekla Open API编写的选择梁的代码：

using Tekla.Structures.Model;
using Tekla.Structures.Geometry3d;

public void SelectBeams()
{
    Model model = new Model();
    
    // Get the selection
    var selection = model.GetModelObjectSelector().GetSelectedObjects();

    // Loop through selected objects
    foreach (var selObj in selection)
    {
        // Check if the selected object is a beam
        if (selObj is Beam)
        {
            Beam beam = selObj as Beam;
            
            // Get the start and end point of the beam
            Point startPoint = beam.StartPoint;
            Point endPoint = beam.EndPoint;

            // Calculate the X direction vector of the beam
            Vector directionVector = startPoint.GetVectorTo(endPoint);
            directionVector.Normalize();

            // Determine if the beam should be selected based on direction of X vector
            if (directionVector.DotProduct(Vector.UnitX) > 0)
            {
                beam.Select();
            }
            else
            {
                beam.Unselect();
            }
        }
    }
}

该代码首先通过Tekla Structures的Model对象获取选择的对象列表。接着，代码通过循环遍历选中的对象，并检测当前对象是否为梁。如果该对象为梁，则获取梁的起点和终点，并计算出梁的方向向量，然后判断该方向向量是否朝向正X方向。如果朝向正X方向，则将该梁选择；反之，则取消选择该梁。