Alignment.md

Alignment Class

Overview

The Alignment class represents a horizontal alignment in Civil3D, typically used for road centerlines, pipelines, or any linear feature. It can contain curves, lines, and spirals.

Namespace

Autodesk.Civil.DatabaseServices

Inheritance Hierarchy

System.Object
  └─ RXObject
      └─ DBObject
          └─ Entity
              └─ Feature
                  └─ Alignment

Key Properties

Property	Type	Description
Name	string	Gets/sets the alignment name
Description	string	Gets/sets the description
Length	double	Gets the total length
StartingStation	double	Gets/sets the starting station value
EndingStation	double	Gets the ending station value
SiteId	ObjectId	Gets/sets the parent site ObjectId
StyleId	ObjectId	Gets/sets the alignment style
Entities	AlignmentEntityCollection	Gets the collection of alignment entities

Key Methods

Method	Return Type	Description
GetProfileViewIds()	ObjectIdCollection	Gets all profile view ObjectIds
GetProfileIds()	ObjectIdCollection	Gets all profile ObjectIds
StationOffset(double, double, out double, out double)	void	Converts XY to station/offset
PointLocation(double, double)	Point3d	Gets XY from station/offset
GetStationAtPoint(Point3d)	double	Gets station at a point

Code Examples

Example 1: Accessing an Alignment

using Autodesk.Civil.DatabaseServices;

using (Transaction tr = civilDoc.Database.TransactionManager.StartTransaction())
{
    ObjectIdCollection alignmentIds = civilDoc.GetAlignmentIds();
    
    if (alignmentIds.Count > 0)
    {
        Alignment alignment = tr.GetObject(alignmentIds[0], OpenMode.ForRead) as Alignment;
        
        ed.WriteMessage($"\nAlignment: {alignment.Name}");
        ed.WriteMessage($"\nLength: {alignment.Length:F2}");
        ed.WriteMessage($"\nStart Station: {alignment.StartingStation:F2}");
        ed.WriteMessage($"\nEnd Station: {alignment.EndingStation:F2}");
    }
    
    tr.Commit();
}

Example 2: Getting Point from Station/Offset

using (Transaction tr = civilDoc.Database.TransactionManager.StartTransaction())
{
    Alignment alignment = tr.GetObject(alignmentId, OpenMode.ForRead) as Alignment;
    
    double station = 100.0;
    double offset = 5.0; // 5 units to the right
    
    Point3d point = alignment.PointLocation(station, offset);
    
    ed.WriteMessage($"\nPoint at Station {station}, Offset {offset}:");
    ed.WriteMessage($"\n  X: {point.X:F2}, Y: {point.Y:F2}");
    
    tr.Commit();
}

Example 3: Converting XY to Station/Offset

using (Transaction tr = civilDoc.Database.TransactionManager.StartTransaction())
{
    Alignment alignment = tr.GetObject(alignmentId, OpenMode.ForRead) as Alignment;
    
    Point3d testPoint = new Point3d(1000, 2000, 0);
    
    double station, offset;
    alignment.StationOffset(testPoint.X, testPoint.Y, out station, out offset);
    
    ed.WriteMessage($"\nPoint ({testPoint.X:F2}, {testPoint.Y:F2}):");
    ed.WriteMessage($"\n  Station: {station:F2}");
    ed.WriteMessage($"\n  Offset: {offset:F2}");
    
    tr.Commit();
}

Example 4: Iterating Through Alignment Entities

using (Transaction tr = civilDoc.Database.TransactionManager.StartTransaction())
{
    Alignment alignment = tr.GetObject(alignmentId, OpenMode.ForRead) as Alignment;
    
    foreach (AlignmentEntity entity in alignment.Entities)
    {
        ed.WriteMessage($"\nEntity Type: {entity.EntityType}");
        ed.WriteMessage($"\n  Start Station: {entity.StartStation:F2}");
        ed.WriteMessage($"\n  End Station: {entity.EndStation:F2}");
        ed.WriteMessage($"\n  Length: {entity.Length:F2}");
        
        if (entity.EntityType == AlignmentEntityType.Arc)
        {
            AlignmentArc arc = entity as AlignmentArc;
            ed.WriteMessage($"\n  Radius: {arc.Radius:F2}");
        }
    }
    
    tr.Commit();
}

Example 5: Getting Associated Profiles

using (Transaction tr = civilDoc.Database.TransactionManager.StartTransaction())
{
    Alignment alignment = tr.GetObject(alignmentId, OpenMode.ForRead) as Alignment;
    
    ObjectIdCollection profileIds = alignment.GetProfileIds();
    
    ed.WriteMessage($"\nProfiles for alignment '{alignment.Name}':");
    
    foreach (ObjectId profileId in profileIds)
    {
        Profile profile = tr.GetObject(profileId, OpenMode.ForRead) as Profile;
        ed.WriteMessage($"\n  {profile.Name}");
    }
    
    tr.Commit();
}

Related Objects

• Profile - Vertical profile along alignment
• CivilDocument - Container for alignments
• Feature - Base class

References

• Autodesk Official Documentation