B站视频：
https://www.bilibili.com/video/BV1Hm411X7Rc/
Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.Geometry
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.EditorInput
Public Class Butterfly_curve1
ReadOnly R As Double = 100 '比例(半径)
ReadOnly T_Total As Integer = 4320 '= 24*180
ReadOnly Pi As Double = Math.PI
ReadOnly e As Double = Math.E
ReadOnly acDc As Document = Application.DocumentManager.MdiActiveDocument
ReadOnly acDb As Database = acDc.Database
ReadOnly T1 As New Timer
Dim I As Integer
Dim Ps As New Point3d(0, 0, 0)
<CommandMethod("TcHuDie")>
Public Sub TcHuDie()
'绘制之前清除以前绘制的，遍历所有对象并删除
Using acTr As Transaction = acDb.TransactionManager.StartTransaction()
Dim Block_Table As BlockTable = acTr.GetObject(acDb.BlockTableId, OpenMode.ForRead)
Dim BlockRecord As BlockTableRecord = acTr.GetObject(Block_Table(BlockTableRecord.ModelSpace), OpenMode.ForWrite)
For Each EntId As ObjectId In BlockRecord
Dim Ent As Entity = acTr.GetObject(EntId, OpenMode.ForWrite)
Try
Ent.Erase()
Catch ex As Exception
acDc.Editor.WriteMessage(vbCrLf & ex.Message)
Continue For
End Try
Next
acTr.Commit()
End Using
'调整当前视口中心点为Point2d(0, 0)
Dim viewTableRecord As ViewTableRecord = acDc.Editor.GetCurrentView()
viewTableRecord.CenterPoint = New Point2d(0, 0)
viewTableRecord.Height = 800
viewTableRecord.Width = 800
acDc.Editor.SetCurrentView(viewTableRecord)
acDc.Editor.UpdateScreen()
T1.Enabled = True
T1.Interval = 5
AddHandler T1.Tick, New EventHandler(AddressOf Timer1_Tick)
T1.Start()
End Sub
Public Sub Timer1_Tick(ByVal sender As Object, ByVal _e As EventArgs)
Dim docLock As Autodesk.AutoCAD.ApplicationServices.DocumentLock = acDc.LockDocument()
I += 1 '增加1度（角度制）
Dim T As Double = I * Pi / 180 '公式中的变量t
Dim Sint As Double = Math.Sin(T)
Dim Cost As Double = Math.Cos(T)
Dim Cos4t As Double = Math.Cos(4 * T)
Dim Sint5 As Double = Math.Sin(T / 24) ^ 5
Dim x As Double = Sint * (e ^ Cost - 2 * Cos4t - Sint5) * R
Dim y As Double = Cost * (e ^ Cost - 2 * Cos4t - Sint5) * R
Dim Pe As New Point3d(x, y, 0)
Dim L As New Line(Ps, Pe) With {
.Color = Autodesk.AutoCAD.Colors.Color.FromRgb(255, 0, 0)
}
AddEnt(L)
Ps = Pe '紧接上一点
'移动鼠标至当前点
Dim point2 As System.Drawing.Point
Dim handle As System.IntPtr = acDc.Window.Handle
point2 = TcFunctions.CAD.ScreenFromWCSPoint_DPI(acDc.Editor, handle, Pe, 0)
WinAPI_USER32.SetCursorPos(point2.X, point2.Y)
acDc.Editor.UpdateScreen()
'当t=24*Pi时 停止绘图
If I >= T_Total Then
I = 0
RemoveHandler T1.Tick, New EventHandler(AddressOf Timer1_Tick)
End If
End Sub
Public Shared Sub AddEnt(ByVal E As Entity)
Dim acDc As Document = Application.DocumentManager.MdiActiveDocument
Dim acDb As Database = acDc.Database
Using acTr As Transaction = acDc.TransactionManager.StartTransaction()
Dim acBt As BlockTable
acBt = acTr.GetObject(acDb.BlockTableId, OpenMode.ForWrite)
Dim acBtRec As BlockTableRecord
acBtRec = acTr.GetObject(acDb.CurrentSpaceId, OpenMode.ForWrite)
acBtRec.AppendEntity(E)
acTr.AddNewlyCreatedDBObject(E, True)
acTr.Commit()
End Using
End Sub
Private Declare Function ClientToScreen Lib "user32.dll" (ByVal hWnd As System.IntPtr,
ByRef pt As System.Drawing.Point) As Boolean
Public Shared Function ScreenFromWCSPoint_DPI(ByVal acEd As Editor,
ByVal hWnd As System.IntPtr,
ByVal wcsPt As Point3d, ByVal _
vpNum As Short) As System.Drawing.Point
Dim point1 As System.Windows.Point = acEd.PointToScreen(wcsPt, CInt(vpNum))
Dim point2 As New System.Drawing.Point(CInt(point1.X * CurrentDPI()), CInt(point1.Y * CurrentDPI()))
ClientToScreen(hWnd, point2)
Return point2
End Function
'Dpi
Public Shared Function CurrentDPI() As Double
Return CDec((Graphics.FromHwnd(IntPtr.Zero).DpiX / 96.0F))
End Function
End Class
