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<a href="/plan9/">Plan 9 from Bell Labs</a>’s /usr/web/sources/contrib/maht/mandlebrot.vb.txt


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Copyright © 2009 Alcatel-Lucent. 
Distributed under the
<a href="/plan9/license.html">Lucent Public License version 1.02</a>.
 
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VERSION 5.00
Begin VB.Form Form1
AutoRedraw = -1 'True
Caption = "No Frills Fractals"
ClientHeight = 6105
ClientLeft = 60
ClientTop = 345
ClientWidth = 5250
LinkTopic = "Form1"
ScaleHeight = 6105
ScaleWidth = 5250
StartUpPosition = 3 'Windows Default
Begin VB.Frame Frame1
Caption = "Julia Parameters"
Height = 1215
Left = 2280
TabIndex = 14
Top = 3360
Width = 2175
Begin VB.TextBox Text7
Height = 285
Left = 960
TabIndex = 18
Text = "0.6"
Top = 720
Width = 855
End
Begin VB.TextBox Text6
Height = 285
Left = 960
TabIndex = 16
Text = "0.3"
Top = 360
Width = 855
End
Begin VB.Label Label7
Caption = "Imaginary"
Height = 255
Left = 120
TabIndex = 17
Top = 720
Width = 735
End
Begin VB.Label Label6
Caption = "Real"
Height = 255
Left = 120
TabIndex = 15
Top = 360
Width = 615
End
End
Begin VB.OptionButton Option2
Caption = "Julia"
Height = 255
Left = 2280
TabIndex = 13
Top = 5040
Width = 855
End
Begin VB.OptionButton Option1
Caption = "Mandelbrot"
Height = 255
Left = 2280
TabIndex = 12
Top = 4680
Value = -1 'True
Width = 1215
End
Begin VB.TextBox Text5
Height = 285
Left = 1200
TabIndex = 11
Text = "100"
Top = 4920
Width = 735
End
Begin VB.TextBox Text4
Height = 285
Left = 1200
TabIndex = 9
Text = "1.5"
Top = 4560
Width = 735
End
Begin VB.TextBox Text3
Height = 285
Left = 1200
TabIndex = 8
Text = "-1.5"
Top = 4200
Width = 735
End
Begin VB.TextBox Text2
Height = 285
Left = 1200
TabIndex = 7
Text = "1.5"
Top = 3840
Width = 735
End
Begin VB.TextBox Text1
Height = 285
Left = 1200
TabIndex = 6
Text = "-2.5"
Top = 3480
Width = 735
End
Begin VB.CommandButton Command1
Caption = "Draw"
Height = 495
Left = 1560
TabIndex = 1
Top = 5400
Width = 1575
End
Begin VB.PictureBox Picture1
Height = 3060
Left = 120
ScaleHeight = 200
ScaleMode = 3 'Pixel
ScaleWidth = 320
TabIndex = 0
Top = 120
Width = 4860
End
Begin VB.Label Label5
Caption = "Iterations"
Height = 255
Left = 120
TabIndex = 10
Top = 4920
Width = 735
End
Begin VB.Label Label4
Caption = "Y Max"
Height = 255
Left = 120
TabIndex = 5
Top = 4560
Width = 855
End
Begin VB.Label Label3
Caption = "Y Min"
Height = 255
Left = 120
TabIndex = 4
Top = 4200
Width = 855
End
Begin VB.Label Label2
Caption = "X Max"
Height = 255
Left = 120
TabIndex = 3
Top = 3840
Width = 855
End
Begin VB.Label Label1
Caption = "X Min"
Height = 255
Left = 120
TabIndex = 2
Top = 3480
Width = 855
End
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
' This program draws no frills fractals
' It's designed to show how to draw fractals rather than to be a fast
' or useful program

Option Explicit

Private Sub Command1_Click()
Dim Xmin As Single
Dim Xmax As Single
Dim Ymin As Single
Dim Ymax As Single
Dim MaxIter As Integer
Dim P As Single
Dim Q As Single
Dim initx As Single
Dim inity As Single
Dim xs As Single
Dim ys As Single
Dim x As Integer
Dim y As Integer
Dim i As Integer

' Read the paramters fro m the text boxes
Xmin = Val(Text1.Text)
Xmax = Val(Text2.Text)
Ymin = Val(Text3.Text)
Ymax = Val(Text4.Text)
MaxIter = Val(Text5.Text)
P = Val(Text6.Text)
Q = Val(Text7.Text)

' This works out the scaling factor for each pixel
xs = (Xmax - Xmin) / Picture1.ScaleWidth
ys = (Ymax - Ymin) / Picture1.ScaleHeight

' now draw the fractal

If Option1.Value = True Then
' Mandelbrot set
For y = 0 To Picture1.ScaleHeight - 1
For x = 0 To Picture1.ScaleWidth - 1
' work out the coordinate of the pixel
initx = Xmin + xs * x
inity = Ymin + ys * y
' iterate with these parameters
i = IterateM(initx, inity, MaxIter)
' plot the pixel
Picture1.PSet (x, y), QBColor((i Mod 15) + 1)
Next
Next

Else

' Julia set
For y = 0 To Picture1.ScaleHeight - 1
For x = 0 To Picture1.ScaleWidth - 1
' work out the coordinate of the pixel
initx = Xmin + xs * x
inity = Ymin + ys * y
' iterate with these parameters
i = IterateJ(initx, inity, MaxIter, P, Q)
' plot the pixel
Picture1.PSet (x, y), QBColor((i Mod 15) + 1)
Next
Next
End If
End Sub

Public Function IterateM(initx As Single, inity As Single, MaxIter As Integer) As Integer
' this function works out how many iterations are needed for a given point on the
' mandelbrot set

' x->x*x-y*y+x0
' y->2*x*y+y0

Dim x As Single
Dim y As Single
Dim xsq As Single
Dim ysq As Single
Dim i As Integer

' precalculate the first iteration
x = initx + initx * initx - inity * inity
y = inity + initx * inity + initx * inity
ysq = y * y
xsq = x * x

For i = 2 To MaxIter
' new imaginary value
y = inity + x * y + x * y
' new real value
x = initx - ysq + xsq
' work out the squared values
ysq = y * y
xsq = x * x
' check the bailout condition
If (xsq + ysq) > 4 Then Exit For
Next i
IterateM = i
End Function

Public Function IterateJ(initx As Single, inity As Single, MaxIter As Integer, P As Single, Q As Single) As Integer
' this function works out how many iterations are needed for a given point on the
' julia set

' x->x*x-y*y+P
' y->2*x*y+Q

Dim x As Single
Dim y As Single
Dim xsq As Single
Dim ysq As Single
Dim i As Integer

' get the initial values of x and y ready
x = initx
y = inity
xsq = x * x
ysq = y * y

For i = 1 To MaxIter
'new imaginary value
y = Q + x * y + x * y
' new real value
x = P - ysq + xsq
' work out the squared values
ysq = y * y
xsq = x * x
' check the bailout condition
If (xsq + ysq) > 4 Then Exit For
Next i

IterateJ = i

End Function

Private Sub Option1_Click()
'if mandelbrot set is clicked, then put in some
' sensible starting coordinates
Text1.Text = -2.5
Text2.Text = 1.5
Text3.Text = -1.5
Text4.Text = 1.5

End Sub

Private Sub Option2_Click()
'if julia set is clicked, then put in some
' sensible starting coordinates

Text1.Text = -1.5
Text2.Text = 1.5
Text3.Text = -1.5
Text4.Text = 1.5

End Sub

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