To have block references inserted at each vertex of a polyline and ensure that they are transformed together, the block reference and the polyline entity can be constrained together using “coincident point” constraint. This will ensure that AutoCAD is aware of the association between them.
Here is a sample code to demonstrate the creation of such coincident point constraint :
private static string _blockName = "Autodesk";
///
/// Creates a Polyline with block references inserted at each vertex.
/// The block references are then constrained to the polyline vertex.
///
[CommandMethod("Demo")]
static public void TestMethod()
{
CreatePlineWithConstrainedBlockRefs();
}
public static void CreatePlineWithConstrainedBlockRefs()
{
CreateBlockDef();
Database db
= Application.DocumentManager.MdiActiveDocument.Database;
Autodesk.AutoCAD.DatabaseServices.TransactionManager tm
= db.TransactionManager;
using (Transaction myT = tm.StartTransaction())
{
BlockTable bt = tm.GetObject(
db.BlockTableId,
OpenMode.ForRead,
false
) as BlockTable;
BlockTableRecord blockDefinition
= tm.GetObject
(
bt[_blockName],
OpenMode.ForRead,
false
) as BlockTableRecord;
BlockTableRecord btr
= tm.GetObject
(
bt[BlockTableRecord.ModelSpace],
OpenMode.ForWrite,
false
) as BlockTableRecord;
Polyline polyline = new Polyline();
polyline.Closed = false;
ObjectIdCollection blkRefIds
= new ObjectIdCollection();
polyline.AddVertexAt(
0,
new Point2d(0.0, 0.0),
0.0,
0.0,
0.0
);
BlockReference blockRef1
= new BlockReference
(
Point3d.Origin,
blockDefinition.ObjectId
);
blkRefIds.Add(btr.AppendEntity(blockRef1));
tm.AddNewlyCreatedDBObject(blockRef1, true);
polyline.AddVertexAt
(
1,
new Point2d(10.0, 10.0),
0.0, 0.0, 0.0
);
BlockReference blockRef2
= new BlockReference
(
new Point3d(10.0, 10.0, 0.0),
blockDefinition.ObjectId
);
blkRefIds.Add(btr.AppendEntity(blockRef2));
tm.AddNewlyCreatedDBObject(blockRef2, true);
polyline.AddVertexAt
(
2,
new Point2d(20.0, 0.0),
0.0, 0.0, 0.0
);
BlockReference blockRef3
= new BlockReference
(
new Point3d(20.0, 0.0, 0.0),
blockDefinition.ObjectId
);
blkRefIds.Add(btr.AppendEntity(blockRef3));
tm.AddNewlyCreatedDBObject(blockRef3, true);
polyline.AddVertexAt
(
3,
new Point2d(30.0, 10.0),
0.0, 0.0, 0.0
);
BlockReference blockRef4
= new BlockReference
(
new Point3d(30.0, 10.0, 0.0),
blockDefinition.ObjectId
);
blkRefIds.Add(btr.AppendEntity(blockRef4));
tm.AddNewlyCreatedDBObject(blockRef4, true);
ObjectId plineOid = btr.AppendEntity(polyline);
tm.AddNewlyCreatedDBObject(polyline, true);
AssociatePline_BlockReference
(
myT,
db,
blkRefIds[0],
plineOid,
0,
0,
false
);
AssociatePline_BlockReference
(
myT,
db,
blkRefIds[1],
plineOid,
0,
1,
false
);
AssociatePline_BlockReference
(
myT,
db,
blkRefIds[2],
plineOid,
1,
1,
false
);
AssociatePline_BlockReference
(
myT,
db,
blkRefIds[3],
plineOid,
2,
1,
true
);
myT.Commit();
}
}
// This method creates a coincident constraint between
// the block reference and the polyline vertex.
public static void AssociatePline_BlockReference
( Transaction trans,
Database db,
ObjectId blkReferenceOid,
ObjectId pLineOid,
int edgeIndex,
int vertexIndex,
bool evaluate
)
{
// Finding the subentityId of the BlockReference vertex
FullSubentityPath subentPath2 = new FullSubentityPath();
using (Entity entity =
(Entity)trans.GetObject(
blkReferenceOid,
OpenMode.ForRead,
false
))
{
AssocPersSubentityIdPE subentityIdPE;
RXClass peCls
= AssocPersSubentityIdPE.GetClass(
typeof(AssocPersSubentityIdPE));
IntPtr pSubentityIdPE = entity.QueryX(peCls);
if (pSubentityIdPE == IntPtr.Zero)
{
System.Windows.MessageBox.Show("cannot get pSubentityIdPE1");
return;
}
subentityIdPE
= AssocPersSubentityIdPE.Create(
pSubentityIdPE,
false
) as AssocPersSubentityIdPE;
if (subentityIdPE == null)
{
System.Windows.MessageBox.Show("cannot get subentityIdPE1");
return;
}
SubentityId[] vertexSubentityId = null;
vertexSubentityId
= subentityIdPE.GetAllSubentities
(
entity,
SubentityType.Vertex
);
if (vertexSubentityId.Length > 0)
{
subentPath2
= new FullSubentityPath
(
new ObjectId[1] { blkReferenceOid },
vertexSubentityId[0]
);
}
}
FullSubentityPath subentEdgePath1 = new FullSubentityPath();
FullSubentityPath subentPath1 = new FullSubentityPath();
using (Entity entity
= (Entity)trans.GetObject(
pLineOid,
OpenMode.ForRead,
false
))
{
AssocPersSubentityIdPE subentityIdPE;
RXClass peCls
= AssocPersSubentityIdPE.GetClass
(
typeof(AssocPersSubentityIdPE)
);
IntPtr pSubentityIdPE = entity.QueryX(peCls);
if (pSubentityIdPE == IntPtr.Zero)
{
System.Windows.MessageBox.Show("cannot get pSubentityIdPE");
return;
}
subentityIdPE
= AssocPersSubentityIdPE.Create
(
pSubentityIdPE,
false
) as AssocPersSubentityIdPE;
if (subentityIdPE == null)
{
System.Windows.MessageBox.Show("cannot get subentityIdPE");
return;
}
SubentityId[] edgeSubentityIds = null;
edgeSubentityIds
= subentityIdPE.GetAllSubentities
(
entity,
SubentityType.Edge
);
SubentityId sid = SubentityId.Null;
sid = edgeSubentityIds[edgeIndex];
SubentityId start = SubentityId.Null,
end = SubentityId.Null;
SubentityId[] other = null;
subentityIdPE.GetEdgeVertexSubentities
(
entity,
sid,
ref start,
ref end,
ref other
);
subentEdgePath1 = new FullSubentityPath
(
new ObjectId[1] { pLineOid },
sid
);
if (vertexIndex == 0)
subentPath1 = new FullSubentityPath
(
new ObjectId[1] { pLineOid },
start
);
else
subentPath1 = new FullSubentityPath
(
new ObjectId[1] { pLineOid },
end
);
}
ObjectId consGrpId = GetConstraintGroup(true);
ConstrainedGeometry consGeomEdge1 = null;
ConstrainedGeometry consGeomEdge2 = null;
using (Assoc2dConstraintGroup constGrp =
(Assoc2dConstraintGroup)trans.GetObject
(
consGrpId,
OpenMode.ForWrite,
false
))
{
try
{
consGeomEdge2
= constGrp.AddConstrainedGeometry(subentPath2);
consGeomEdge1
= constGrp.AddConstrainedGeometry(subentEdgePath1);
}
catch (System.Exception ex)
{
// The Geometry might already be in the constraint
// group, in which case we can ignore it and only
// try and add the geometrical constraint.
}
FullSubentityPath[] paths
= new FullSubentityPath[2]
{
subentPath1,
subentPath2
};
GeometricalConstraint newConstraint
= constGrp.AddGeometricalConstraint
(
GeometricalConstraint.ConstraintType.Coincident,
paths
);
if (evaluate)
{
String temp = "";
ObjectId networkId
= AssocNetwork.GetInstanceFromDatabase
(
db,
true,
temp
);
using (AssocNetwork network
= (AssocNetwork)trans.GetObject(
networkId,
OpenMode.ForWrite,
false
))
{
AssocEvaluationCallback callBack = null;
network.Evaluate(callBack);
}
}
}
}
public static void CreateBlockDef()
{
Document activeDoc = Application.DocumentManager.MdiActiveDocument;
Database db = activeDoc.Database;
Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
using (Transaction tr = db.TransactionManager.StartTransaction())
{
BlockTable bt
= (BlockTable)tr.GetObject
(
db.BlockTableId,
OpenMode.ForRead
);
if (bt.Has(_blockName) == false)
{
bt.UpgradeOpen();
BlockTableRecord btr = new BlockTableRecord();
btr.Name = _blockName;
btr.Origin = Point3d.Origin;
bt.Add(btr);
tr.AddNewlyCreatedDBObject(btr, true);
// Circle
Circle circle
= new Circle(Point3d.Origin, Vector3d.ZAxis, 1.0);
btr.AppendEntity(circle);
tr.AddNewlyCreatedDBObject(circle, true);
}
tr.Commit();
}
}
// Helper function to retrieve (or create) constraint group
static private ObjectId GetConstraintGroup(bool createIfDoesNotExist)
{
// get the current UCS plane
Autodesk.AutoCAD.EditorInput.Editor ed
= Application.DocumentManager.MdiActiveDocument.Editor;
Matrix3d ucsMatrix = ed.CurrentUserCoordinateSystem;
Point3d origin = ucsMatrix.CoordinateSystem3d.Origin;
Vector3d xAxis = ucsMatrix.CoordinateSystem3d.Xaxis;
Vector3d yAxis = ucsMatrix.CoordinateSystem3d.Yaxis;
Vector3d zAxis = ucsMatrix.CoordinateSystem3d.Zaxis;
origin += (double)Application.GetSystemVariable("ELEVATION") * zAxis;
Plane currentPlane = new Plane(origin, xAxis, yAxis);
// get the constraint group from block table record
Database database = HostApplicationServices.WorkingDatabase;
ObjectId idConstrGroup = ObjectId.Null;
if (database == null)
{
System.Windows.MessageBox.Show("working database is null");
return idConstrGroup;
}
ObjectId networkId
= AssocNetwork.GetInstanceFromObject(
database.CurrentSpaceId,
createIfDoesNotExist,
true,
""
);
if (networkId.IsNull)
{
System.Windows.MessageBox.Show("network id is null");
return idConstrGroup; // AcDbObjectId::kNull;
}
// Try to find the constraint group in the associative network
Database db = Application.DocumentManager.MdiActiveDocument.Database;
Autodesk.AutoCAD.DatabaseServices.TransactionManager tm
= db.TransactionManager;
using (Transaction myT = tm.StartTransaction())
{
using (AssocNetwork network
= (AssocNetwork)myT.GetObject(
networkId,
OpenMode.ForRead,
false
))
{
if (network == null)
return idConstrGroup;
ObjectIdCollection actionsInNetwork = network.GetActions;
for (int nCount = 0; nCount < actionsInNetwork.Count; nCount++)
{
ObjectId idAction = actionsInNetwork[nCount];
if (idAction == ObjectId.Null)
continue;
if (idAction.ObjectClass.IsDerivedFrom(
RXObject.GetClass(
typeof(Assoc2dConstraintGroup))))
{
using (AssocAction action
= (AssocAction)myT.GetObject
(
idAction,
OpenMode.ForRead,
false
))
{
if (action == null)
continue;
Assoc2dConstraintGroup constGrp
= (Assoc2dConstraintGroup)action;
// In AutoCAD 2011
//constGrp.GetWorkPlane.IsCoplanarTo(currentPlane)
// In AutoCAD 2013
if (constGrp.WorkPlane.IsCoplanarTo(currentPlane))
{
return idAction;
}
}
}
}
}
if (idConstrGroup.IsNull && createIfDoesNotExist)
{
using (AssocNetwork network
= (AssocNetwork)myT.GetObject(
networkId,
OpenMode.ForWrite,
false
))
{
Database databaseN = network.Database;
bool bIsModelSpace = database.TileMode;
Point3d extmin
= bIsModelSpace ? database.Extmin : database.Pextmin;
Point3d extmax
= bIsModelSpace ? database.Extmax : database.Pextmax;
//If model extent is far far away from origin
// then we need to shift construction plane
// origin within the model extent.
Plane constraintPlane = new Plane(currentPlane);
if (extmin.GetAsVector().Length > 1.0e8)
{
Point3d originL
= extmin + (extmax - extmin) / 2.0;
PointOnSurface result
= currentPlane.GetClosestPointTo(originL);
constraintPlane.Set(result.GetPoint(), currentPlane.Normal);
}
using (Assoc2dConstraintGroup constGrp
= new Assoc2dConstraintGroup(constraintPlane))
{
idConstrGroup = database.AddDBObject(constGrp);
}
network.AddAction(idConstrGroup, true);
}
}
myT.Commit();
}
return idConstrGroup;
}
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