A polyface mesh represents the surface of an object defined by faces capable of having numerous vertices. Creating a polyface mesh is similar to creating a rectangular mesh. You create a polyface mesh by creating an instance of a PolyFaceMesh object. The constructor of the PolyFaceMesh object does not accept any parameters. To add a vertex to a polyface mesh, you create a PolyFaceMeshVertex and add it to the PolyFaceMesh object using the AppendVertex method.
As you create the polyface mesh, you can set specific edges to be invisible, assign them to layers, or give them colors. To make an edge invisible, you create an instance of a FaceRecord and set which edges should be invisible and then append the FaceRecord object to the PolyFaceMesh object using the AppendFaceRecord method.
This example creates a PolyfaceMesh object and changes the viewing direction of the active viewport to display the three-dimensional nature of the mesh.
Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
<CommandMethod("CreatePolyfaceMesh")> _
Public Sub CreatePolyfaceMesh()
'' Get the current document and database, and start a transaction
Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument
Dim acCurDb As Database = acDoc.Database
Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()
'' Open the Block table for read
Dim acBlkTbl As BlockTable
acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId, _
OpenMode.ForRead)
'' Open the Block table record Model space for write
Dim acBlkTblRec As BlockTableRecord
acBlkTblRec = acTrans.GetObject(acBlkTbl(BlockTableRecord.ModelSpace), _
OpenMode.ForWrite)
'' Create a polyface mesh
Using acPFaceMesh As PolyFaceMesh = New PolyFaceMesh()
'' Add the new object to the block table record and the transaction
acBlkTblRec.AppendEntity(acPFaceMesh)
acTrans.AddNewlyCreatedDBObject(acPFaceMesh, True)
'' Before adding vertexes, the polyline must be in the drawing
Dim acPts3dPFMesh As Point3dCollection = New Point3dCollection()
acPts3dPFMesh.Add(New Point3d(4, 7, 0))
acPts3dPFMesh.Add(New Point3d(5, 7, 0))
acPts3dPFMesh.Add(New Point3d(6, 7, 0))
acPts3dPFMesh.Add(New Point3d(4, 6, 0))
acPts3dPFMesh.Add(New Point3d(5, 6, 0))
acPts3dPFMesh.Add(New Point3d(6, 6, 1))
For Each acPt3d As Point3d In acPts3dPFMesh
Dim acPMeshVer As PolyFaceMeshVertex = New PolyFaceMeshVertex(acPt3d)
acPFaceMesh.AppendVertex(acPMeshVer)
acTrans.AddNewlyCreatedDBObject(acPMeshVer, True)
Next
Using acFaceRec1 As FaceRecord = New FaceRecord(1, 2, 5, 4)
acPFaceMesh.AppendFaceRecord(acFaceRec1)
acTrans.AddNewlyCreatedDBObject(acFaceRec1, True)
End Using
Using acFaceRec2 As FaceRecord = New FaceRecord(2, 3, 6, 5)
acPFaceMesh.AppendFaceRecord(acFaceRec2)
acTrans.AddNewlyCreatedDBObject(acFaceRec2, True)
End Using
End Using
'' Open the active viewport
Dim acVportTblRec As ViewportTableRecord
acVportTblRec = acTrans.GetObject(acDoc.Editor.ActiveViewportId, _
OpenMode.ForWrite)
'' Rotate the view direction of the current viewport
acVportTblRec.ViewDirection = New Vector3d(-1, -1, 1)
acDoc.Editor.UpdateTiledViewportsFromDatabase()
'' Save the new objects to the database
acTrans.Commit()
End Using
End Sub
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
[CommandMethod("CreatePolyfaceMesh")]
public static void CreatePolyfaceMesh()
{
// Get the current document and database, and start a transaction
Document acDoc = Application.DocumentManager.MdiActiveDocument;
Database acCurDb = acDoc.Database;
using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{
// Open the Block table record for read
BlockTable acBlkTbl;
acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
OpenMode.ForRead) as BlockTable;
// Open the Block table record Model space for write
BlockTableRecord acBlkTblRec;
acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
OpenMode.ForWrite) as BlockTableRecord;
// Create a polyface mesh
using (PolyFaceMesh acPFaceMesh = new PolyFaceMesh())
{
// Add the new object to the block table record and the transaction
acBlkTblRec.AppendEntity(acPFaceMesh);
acTrans.AddNewlyCreatedDBObject(acPFaceMesh, true);
// Before adding vertexes, the polyline must be in the drawing
Point3dCollection acPts3dPFMesh = new Point3dCollection();
acPts3dPFMesh.Add(new Point3d(4, 7, 0));
acPts3dPFMesh.Add(new Point3d(5, 7, 0));
acPts3dPFMesh.Add(new Point3d(6, 7, 0));
acPts3dPFMesh.Add(new Point3d(4, 6, 0));
acPts3dPFMesh.Add(new Point3d(5, 6, 0));
acPts3dPFMesh.Add(new Point3d(6, 6, 1));
foreach (Point3d acPt3d in acPts3dPFMesh)
{
PolyFaceMeshVertex acPMeshVer = new PolyFaceMeshVertex(acPt3d);
acPFaceMesh.AppendVertex(acPMeshVer);
acTrans.AddNewlyCreatedDBObject(acPMeshVer, true);
}
using (FaceRecord acFaceRec1 = new FaceRecord(1, 2, 5, 4))
{
acPFaceMesh.AppendFaceRecord(acFaceRec1);
acTrans.AddNewlyCreatedDBObject(acFaceRec1, true);
}
using (FaceRecord acFaceRec2 = new FaceRecord(2, 3, 6, 5))
{
acPFaceMesh.AppendFaceRecord(acFaceRec2);
acTrans.AddNewlyCreatedDBObject(acFaceRec2, true);
}
}
// Open the active viewport
ViewportTableRecord acVportTblRec;
acVportTblRec = acTrans.GetObject(acDoc.Editor.ActiveViewportId,
OpenMode.ForWrite) as ViewportTableRecord;
// Rotate the view direction of the current viewport
acVportTblRec.ViewDirection = new Vector3d(-1, -1, 1);
acDoc.Editor.UpdateTiledViewportsFromDatabase();
// Save the new objects to the database
acTrans.Commit();
}
}
Sub CreatePolyfaceMesh()
'Define the mesh vertices
Dim vertex(0 To 17) As Double
vertex(0) = 4: vertex(1) = 7: vertex(2) = 0
vertex(3) = 5: vertex(4) = 7: vertex(5) = 0
vertex(6) = 6: vertex(7) = 7: vertex(8) = 0
vertex(9) = 4: vertex(10) = 6: vertex(11) = 0
vertex(12) = 5: vertex(13) = 6: vertex(14) = 0
vertex(15) = 6: vertex(16) = 6: vertex(17) = 1
' Define the face list
Dim FaceList(0 To 7) As Integer
FaceList(0) = 1
FaceList(1) = 2
FaceList(2) = 5
FaceList(3) = 4
FaceList(4) = 2
FaceList(5) = 3
FaceList(6) = 6
FaceList(7) = 5
' Create the polyface mesh
Dim polyfaceMeshObj As AcadPolyfaceMesh
Set polyfaceMeshObj = ThisDrawing.ModelSpace. _
AddPolyfaceMesh(vertex, FaceList)
' Change the viewing direction of the viewport to
' better see the polyface mesh
Dim NewDirection(0 To 2) As Double
NewDirection(0) = -1
NewDirection(1) = -1
NewDirection(2) = 1
ThisDrawing.ActiveViewport.direction = NewDirection
ThisDrawing.ActiveViewport = ThisDrawing.ActiveViewport
ZoomAll
End Sub