①: 隱藏實體

     在CAD的開發(fā)中，有時候我們需要根據(jù)用戶的需求隱藏和顯示一些實體，對于實體本身的屬性Visible當(dāng)然可以實現(xiàn)隱藏、顯示實體，不過，除此之外，我們還可以將一個層上的實體同時隱藏起來，這就要使用LayerTableRecord中的IsOff屬性，并且隱藏的實體ObjectId可以出現(xiàn)在SelectAll()的集合中.當(dāng)然，他們之間還是有區(qū)別的，當(dāng)你用Ctrl+A，選中當(dāng)前活動文檔的全部實體是，你就會發(fā)現(xiàn)原來他們之間區(qū)別。

     簡單的測試程序：

代碼

 1  #region 測試圖層的IsOff和實體的Visible是否一致
 2         [CommandMethod("TestLayer")]
 3         public void TestLayerVis()
 4         {
 5             //選擇一點創(chuàng)建實體
 6             PromptPointOptions opt = new PromptPointOptions("選擇起始點:");
 7             PromptPointResult res = ed.GetPoint(opt);
 8             if (PromptStatus.OK == res.Status)
 9             {
10                 Point3d sPt = res.Value;
11                 using (Transaction trans = db.TransactionManager.StartTransaction())
12                 {
13                     BlockTable bt = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForRead);
14                     BlockTableRecord btr = (BlockTableRecord)trans.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);
15                     //直線，其所在層為默認(rèn)的層
16                     Line line = new Line();
17                     line.StartPoint = sPt;
18                     line.EndPoint = new Point3d(sPt.X + 100, sPt.Y + 50, 0);
19                     //圓，指定層
20                     Circle c = new Circle(sPt, new Vector3d(0, 0, 1), 30);
21                     c.LayerId = CreateLayer("TestLayer");
22                     line.Visible = false; //不顯示實體
23                     btr.AppendEntity(line);
24                     btr.AppendEntity(c);
25                     trans.AddNewlyCreatedDBObject(line, true);
26                     trans.AddNewlyCreatedDBObject(c, true);
27 
28                     LayerTable lt = (LayerTable)trans.GetObject(db.LayerTableId, OpenMode.ForRead);
29                     LayerTableRecord ltr = (LayerTableRecord)trans.GetObject(CreateLayer("TestLayer"), OpenMode.ForWrite);
30                     ltr.IsOff = true; //關(guān)閉圖層，隱藏圖層上的實體
31 
32                     trans.Commit();
33                 }
34             }
35         }
36 
37         //創(chuàng)建一個圖層
38         private ObjectId CreateLayer(string layerName)
39         {
40             ObjectId objId = ObjectId.Null;
41             using (Transaction trans = db.TransactionManager.StartTransaction())
42             {
43                 LayerTable lt = (LayerTable)trans.GetObject(db.LayerTableId, OpenMode.ForWrite);
44                 if (lt.Has(layerName))
45                 {
46                     objId = lt[layerName];
47                 }
48                 else
49                 {
50                     LayerTableRecord ltr = new LayerTableRecord();
51                     ltr.Name = layerName;
52                     objId = lt.Add(ltr);
53                     trans.AddNewlyCreatedDBObject(ltr, true);
54                     trans.Commit();
55                 }
56             }
57 
58             return objId;
59         }
60        #endregion 

②:修改線寬

     有的時候我們?yōu)榱舜蛴〕鰜淼膱D片更加的清楚，可能會設(shè)計到修改實體的線寬,對于多段線，我們很容易想到使用ConstantWidth，這樣就可以修改其線寬了，其實，對于圓或是直線也一樣，不過我們在修改他們的線寬之前要保證系統(tǒng)變量的lwdisplay的值為1(開),這時我們再設(shè)置LineWeight,就可以改變他們的線寬了。

     簡單的測試程序：

代碼

 1  #region 測試直線、圓的LineWeight和PolyLine的ConstantWidth之間的區(qū)別
 2         [CommandMethod("TestLW")]
 3         public void TestLW()
 4         {
 5             PromptPointOptions opt = new PromptPointOptions("選擇起點:");
 6             PromptPointResult res = ed.GetPoint(opt);
 7             if (PromptStatus.OK == res.Status)
 8             {
 9                 Point3d sPt = res.Value;
10                 ObjectId plId = ObjectId.Null;
11                 ObjectId circleId = ObjectId.Null;
12                 using (Transaction trans = db.TransactionManager.StartTransaction())
13                 {
14                     BlockTable bt = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForRead);
15                     BlockTableRecord btr = (BlockTableRecord)trans.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);
16 
17                     //創(chuàng)建一個多段線
18                     Polyline pl = new Polyline();
19                     pl.AddVertexAt(0, sPt.Convert2d(new Plane()), 0, 0, 0);
20                     pl.AddVertexAt(1, new Point3d(sPt.X + 100, sPt.Y + 50, 0).Convert2d(new Plane()), 0, 0, 0);
21                     pl.AddVertexAt(2, new Point3d(sPt.X + 150, sPt.Y - 150, 0).Convert2d(new Plane()), 0, 0, 0);
22 
23                     //創(chuàng)建一個圓
24                     Circle c = new Circle(sPt, new Vector3d(0, 0, 1), 40);
25 
26                     plId = btr.AppendEntity(pl);
27                     circleId = btr.AppendEntity(c);
28                     trans.AddNewlyCreatedDBObject(pl, true);
29                     trans.AddNewlyCreatedDBObject(c, true);
30                     //修改線寬
31                     pl.ConstantWidth = 0.15;
32                     c.LineWeight = LineWeight.LineWeight035;//絕對線寬
33 
34                     trans.Commit();
35                 }
36             }
37         }
38         #endregion

③:多段線凸起

      這個功能一般用在兩條多段線相交時，區(qū)分多段線的走向而特意使相交的多段線在交點出凸起一個"小弧",在這個應(yīng)用中，我們會發(fā)現(xiàn)PolyLine中的AddVertexAt的奇妙之處(插入點的序號可以小于PLine的節(jié)點數(shù)目，PLine的原有節(jié)點的序號會因為有新插入點而自增)。    

      簡單的測試程序：

代碼

 1  [CommandMethod("TestPolyLine")]
 2         public void TestPolyLine()
 3         {
 4             PromptPointOptions opt = new PromptPointOptions("選擇起點:");
 5             PromptPointResult res = ed.GetPoint(opt);
 6             if (PromptStatus.OK == res.Status)
 7             {
 8                 Point3d sPt = res.Value;
 9                 ObjectId plId = ObjectId.Null;
10                 ObjectId circleId = ObjectId.Null;
11                 Polyline pl = new Polyline();
12                 using (Transaction trans = db.TransactionManager.StartTransaction())
13                 {
14                     BlockTable bt = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForRead);
15                     BlockTableRecord btr = (BlockTableRecord)trans.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);
16 
17                     //創(chuàng)建一個多段線
18                     pl.AddVertexAt(0, sPt.Convert2d(new Plane()), 0, 0, 0);
19                     pl.AddVertexAt(1, new Point3d(sPt.X + 200, sPt.Y + 150, 0).Convert2d(new Plane()), 0, 0, 0);
20                     pl.AddVertexAt(2, new Point3d(sPt.X + 400, sPt.Y + 80, 0).Convert2d(new Plane()), 0, 0, 0);
21 
22                     btr.AppendEntity(pl);
23                     trans.AddNewlyCreatedDBObject(pl, true);
24                     ////加一個小弧
25                     Point3d pt1 = pl.GetPointAtDist(80);
26                     Point3d pt2 = pl.GetPointAtDist(100);
27                     pl.AddVertexAt(1, pt1.Convert2d(new Plane()), 0, 0, 0);
28                     pl.AddVertexAt(2, pt2.Convert2d(new Plane()), 0, 0, 0);
29                     pl.SetBulgeAt(1, 0.78);
30                     
31                     trans.Commit();
32                 }
33                 
34             }
35         }