Public Class Form1
    Public Const Pi = 3.14159265358979
    Function 色設定(種類 As Integer, CH As Integer) As Color
        If 種類 = 1 Then
            色設定 = Color.FromArgb(0, CH * 64, 0)
        Else
            色設定 = Color.FromArgb(CH * 64, CH * 64, 0)
        End If
    End Function
    Function IX(X As Double) As Integer
        IX = 0.5 * X + 200 + 0.5
    End Function
    Function IY(Y As Double) As Integer
        IY = 300 - Y * 0.5 + 0.5
    End Function
    Private Sub DrawStalk(種類 As Integer,
                           X1 As Double, Y1 As Double, X2 As Double, _
                           Y2 As Double, X3 As Double, Y3 As Double, _
                           X4 As Double, Y4 As Double) '茎描画
        Dim DX As Double, DY As Double, DX1 As Double, DY1 As Double
        Dim DX2 As Double, DY2 As Double, X As Double, Y As Double
        Dim XX2 As Double, YY2 As Double, i As Integer, CH As Integer
        Dim g As Graphics = PictureBox1.CreateGraphics()
        Dim P As Pen
        DX = X2 - X1 : DY = Y2 - Y1
        If Math.Abs(DX) > Math.Abs(DY) Then
            DX1 = DX / 5 : DY1 = DY / 5
            DX2 = (X4 - X3) / 5 : DY2 = (Y4 - Y3) / 5
            Y = Y1 : XX2 = X3 : YY2 = Y3
            i = 0
            For X = X1 To X2 Step DX1
                CH = i Mod 3 : P = New Pen(色設定(種類, CH))
                g.DrawLine(P, IX(X), IY(Y), IX(XX2), IY(YY2))
                Y = Y + DY1 : XX2 = XX2 + DX2 : YY2 = YY2 + DY2
                i = i + 1
            Next
        Else
            DX1 = DX / 5 : DY1 = DY / 5
            DX2 = (X4 - X3) / 5 : DY2 = (Y4 - Y3) / 5
            X = X1 : XX2 = X3 : YY2 = Y3 : i = 0
            For Y = Y1 To Y2 Step DY1
                CH = i Mod 3 : P = New Pen(色設定(種類, CH))
                g.DrawLine(P, IX(X), IY(Y), IX(XX2), IY(YY2))
                X = X + DX1 : XX2 = XX2 + DX2 : YY2 = YY2 + DY2
                i = i + 1
            Next
        End If
    End Sub
    Private Sub DrawStalk1(X1 As Double, Y1 As Double, X2 As Double, _
                           Y2 As Double, X3 As Double, Y3 As Double, _
                           X4 As Double, Y4 As Double) '　緑っぽい茎の描画
        DrawStalk(1, X1, Y1, X2, Y2, X3, Y3, X4, Y4)
    End Sub
    Private Sub DrawStalk2(X1 As Double, Y1 As Double, X2 As Double, _
                           Y2 As Double, X3 As Double, Y3 As Double, _
                           X4 As Double, Y4 As Double) '茶色っぽい茎描画
        DrawStalk(2, X1, Y1, X2, Y2, X3, Y3, X4, Y4)
    End Sub
    Private Sub DrawFern(X As Double, Y As Double, W As Double, _
                         L As Double, TH As Double, DTH As Double)
        Dim X0 As Double, Y0 As Double, XN As Double, YN As Double
        Dim X1 As Double, Y1 As Double, X2 As Double, Y2 As Double
        Dim X3 As Double, Y3 As Double, X4 As Double, Y4 As Double
        Dim XX1 As Double, YY1 As Double, XX2 As Double, YY2 As Double
        Dim cosTH As Double, sinTH As Double
        Dim TH0 As Double, WW As Double, LL As Double
        Dim g As Graphics = PictureBox1.CreateGraphics()
        Dim P As Pen = New Pen(Color.Black)

        X0 = X : Y0 = Y : TH0 = TH : WW = W : LL = L
        cosTH = Math.Cos(TH0) : sinTH = Math.Sin(TH0)
        X1 = X0 - WW * sinTH : Y1 = Y0 + WW * cosTH
        X2 = X0 + WW * sinTH : Y2 = Y0 - WW * cosTH
        Do While WW > 0.05
            WW = WW * 0.95
            XN = X0 + LL * cosTH : YN = Y0 + LL * sinTH
            X3 = XN - WW * sinTH : Y3 = YN + WW * cosTH
            X4 = XN + WW * sinTH : Y4 = YN - WW * cosTH
            DrawStalk1(X1, Y1, X2, Y2, X3, Y3, X4, Y4)
            XX1 = X1 - 3 * WW * sinTH : YY1 = Y1 + 3 * WW * cosTH
            XX2 = X2 + 3 * WW * sinTH : YY2 = Y2 - 3 * WW * cosTH
            g.DrawLine(P, IX(X1), IY(Y1), IX(XX1), IY(YY1))
            g.DrawLine(P, IX(X2), IY(Y2), IX(XX2), IY(YY2))
            DrawFern(X1 - 3 * WW * sinTH, Y1 + 3 * WW * cosTH, _
            WW * 0.3, LL * 0.3, TH + Pi / 3, Math.Abs(DTH) * 0.8)
            DrawFern(X2 + 3 * WW * sinTH, Y2 - 3 * WW * cosTH, _
            WW * 0.3, LL * 0.3, TH - Pi / 3, -Math.Abs(DTH) * 0.8)
            X0 = XN : Y0 = YN : X1 = X3 : Y1 = Y3 : X2 = X4 : Y2 = Y4
            TH0 = TH0 - DTH
            cosTH = Math.Cos(TH0) : sinTH = Math.Sin(TH0)
            LL = LL * 0.9
        Loop
    End Sub
    '樹木の描画
    Private Sub DrawTree(X As Double, Y As Double, W As Double, _
                         L As Double, TH As Double, DTH As Double)
        Dim X0 As Double, Y0 As Double, XN As Double, YN As Double
        Dim X1 As Double, Y1 As Double, X2 As Double, Y2 As Double
        Dim X3 As Double, Y3 As Double, X4 As Double, Y4 As Double
        Dim DX As Double, DY As Double, i As Integer
        Dim cosTH As Double, sinTH As Double, TH0 As Double, WW As Double, LL As Double
        Dim g As Graphics = PictureBox1.CreateGraphics()
        Dim P As Brush = New SolidBrush(Color.DarkGreen)
        X0 = X : Y0 = Y : TH0 = TH : WW = W : LL = L
        cosTH = Math.Cos(TH0) : sinTH = Math.Sin(TH0)
        X1 = X0 - WW * sinTH : Y1 = Y0 + WW * cosTH
        X2 = X0 + WW * sinTH : Y2 = Y0 - WW * cosTH
        If L < 10 Then
            For i = 1 To 10
                DX = (Rnd() - 0.5) * 100 : DY = (Rnd() - 0.5) * 100
                g.FillEllipse(P, IX(X + DX), IY(Y + DY), 2, 2)
            Next
            Exit Sub
        End If
        i = 0
        Do While WW > 0.1
            WW = WW * 0.95
            XN = X0 + LL * cosTH : YN = Y0 + LL * sinTH
            X3 = XN - WW * sinTH : Y3 = YN + WW * cosTH
            X4 = XN + WW * sinTH : Y4 = YN - WW * cosTH
            DrawStalk2(X1, Y1, X2, Y2, X3, Y3, X4, Y4)
            i = i + 1
            If i = 5 Then
                DrawTree(X1, Y1, WW * 0.8, LL * 0.8, TH + Pi / 6, Math.Abs(DTH) * 0.8)
                DrawTree(X2, Y2, WW * 0.8, LL * 0.8, TH - Pi / 6, -Math.Abs(DTH) * 0.8)
            ElseIf i > 5 Then
                If i Mod 5 = 0 Then
                    DrawTree(X1, Y1, WW * 0.8, LL * 0.8, TH + Pi / 6, Math.Abs(DTH) * 0.8)
                ElseIf i Mod 5 = 2 Then
                    DrawTree(X2, Y2, WW * 0.8, LL * 0.8, TH - Pi / 6, -Math.Abs(DTH) * 0.8)
                End If
            End If
            X0 = XN : Y0 = YN : X1 = X3 : Y1 = Y3 : X2 = X4 : Y2 = Y4
            TH0 = TH0 - DTH
            cosTH = Math.Cos(TH0) : sinTH = Math.Sin(TH0)
            LL = LL * 0.9
        Loop
    End Sub
    ' スギナ描画
    Private Sub DrawSugina(X As Double, Y As Double, W As Double, _
                         L As Double, TH As Double, DTH As Double)
        Dim X0 As Double, Y0 As Double, XN As Double, YN As Double
        Dim X1 As Double, Y1 As Double, X2 As Double, Y2 As Double
        Dim X3 As Double, Y3 As Double, X4 As Double, Y4 As Double
        Dim i As Integer
        Dim cosTH As Double, sinTH As Double, TH0 As Double, WW As Double, LL As Double
        Dim g As Graphics = PictureBox1.CreateGraphics()
        Dim P As Brush = New SolidBrush(Color.DarkGreen)

        X0 = X : Y0 = Y : TH0 = TH : WW = W : LL = L
        cosTH = Math.Cos(TH0) : sinTH = Math.Sin(TH0)
        X1 = X0 - WW * sinTH : Y1 = Y0 + WW * cosTH
        X2 = X0 + WW * sinTH : Y2 = Y0 - WW * cosTH
        'DLW = LL * 4
        i = 0
        Do While WW > 0.1
            WW = WW * 0.95
            XN = X0 + LL * cosTH : YN = Y0 + LL * sinTH
            X3 = XN - WW * sinTH : Y3 = YN + WW * cosTH
            X4 = XN + WW * sinTH : Y4 = YN - WW * cosTH
            i = (i + 1) Mod 2
            If i = 0 Then
                DrawSugina(X1, Y1, WW * 0.3, LL * 0.3, TH + Pi / 3, Math.Abs(DTH) * 0.8)
                DrawSugina(X2, Y2, WW * 0.3, LL * 0.3, TH - Pi / 3, -Math.Abs(DTH) * 0.8)
            End If
            DrawStalk1(X1, Y1, X2, Y2, X3, Y3, X4, Y4)
            X0 = XN : Y0 = YN : X1 = X3 : Y1 = Y3 : X2 = X4 : Y2 = Y4
            TH0 = TH0 - DTH : cosTH = Math.Cos(TH0) : sinTH = Math.Sin(TH0)
            LL = LL * 0.9
        Loop
    End Sub
    ' キリンソウ描画
    Private Sub DrawKirinsou(X As Double, Y As Double, W As Double, _
                         L As Double, TH As Double, DTH As Double)
        Dim X0 As Double, Y0 As Double, XN As Double, YN As Double
        Dim X1 As Double, Y1 As Double, X2 As Double, Y2 As Double
        Dim X3 As Double, Y3 As Double, X4 As Double, Y4 As Double
        Dim DX As Double, DY As Double, i As Integer
        Dim cosTH As Double, sinTH As Double, TH0 As Double, WW As Double, LL As Double
        Dim g As Graphics = PictureBox1.CreateGraphics()
        Dim P As Brush = New SolidBrush(Color.DarkGreen)
        X0 = X : Y0 = Y : TH0 = TH : WW = W : LL = L
        cosTH = Math.Cos(TH0) : sinTH = Math.Sin(TH0)
        X1 = X0 - WW * sinTH : Y1 = Y0 + WW * cosTH
        X2 = X0 + WW * sinTH : Y2 = Y0 - WW * cosTH
        If L < 5 Then
            For i = 1 To 10
                DX = (Rnd() - 0.5) * 7 : DY = (Rnd() - 0.5) * 7
                P = New SolidBrush(Color.FromArgb(i * 25.5, 0, 0))
                g.FillEllipse(P, IX(X + DX), IY(Y + DY), 2, 2)
            Next
            Exit Sub
        End If
        i = 0
        Do While WW > 0.1
            WW = WW * 0.95
            XN = X0 + LL * cosTH : YN = Y0 + LL * sinTH
            X3 = XN - WW * sinTH : Y3 = YN + WW * cosTH
            X4 = XN + WW * sinTH : Y4 = YN - WW * cosTH
            i = (i + 1) Mod 2
            If i = 0 Then
                DrawKirinsou(X1, Y1, WW * 0.3, LL * 0.3, TH + Pi / 3, Math.Abs(DTH) * 0.8)
            Else
                DrawKirinsou(X2, Y2, WW * 0.3, LL * 0.3, TH - Pi / 3, -Math.Abs(DTH) * 0.8)
            End If
            DrawStalk1(X1, Y1, X2, Y2, X3, Y3, X4, Y4)
            X0 = XN : Y0 = YN : X1 = X3 : Y1 = Y3 : X2 = X4 : Y2 = Y4
            TH0 = TH0 - DTH
            cosTH = Math.Cos(TH0) : sinTH = Math.Sin(TH0)
            LL = LL * 0.9
        Loop
    End Sub
    Private Sub delSCR()
        Dim g As Graphics = PictureBox1.CreateGraphics()
        g.Clear(Color.White)
    End Sub
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        delSCR()
    End Sub
    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        delSCR() : DrawStalk1(-5, -5, -5, 0, 5, -5, 5, 0)
        DrawFern(0, 0, 5, 60, Pi / 2, 0.05)
    End Sub
    Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click
        delSCR() : DrawStalk2(-5, -5, -5, 0, 5, -5, 5, 0)
        DrawTree(0, 0, 5, 50, Pi / 2, 0.02)
    End Sub
    Private Sub Button4_Click(sender As System.Object, e As System.EventArgs) Handles Button4.Click
        delSCR() : DrawStalk1(-5, -5, -5, 0, 5, -5, 5, 0)
        DrawSugina(0, 0, 5, 50, Pi / 2, 0.05)
    End Sub
    Private Sub Button5_Click(sender As System.Object, e As System.EventArgs) Handles Button5.Click
        delSCR() : DrawStalk1(-5, -5, -5, 0, 5, -5, 5, 0)
        DrawKirinsou(0, 0, 5, 50, Pi / 2, 0.02)
    End Sub
End Class