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Fractals : Julia Set

Plots a fractal based on the Julia set

Form layout and controls are shown below:

Control Objects Required:

Control Properties:

Typical Code:

Dim a, b, i, j, cx, cy, w As Variant   'These are defined in General
Dim iterations As Variant


Function My_Red(iterations)
    If iterations < 10 Then
        My_Red = 255
    Else
        My_Red = 0
    End If
End Function

Function My_Green(iterations)
    My_Green = (300 * iterations) Mod 128
End Function

Function My_Blue(iterations)
    My_Blue = (400 * iterations) Mod 256
End Function

Function next_real(a, b, i, j)
    RealC = (i - cx) / w * 2 - 1
    IMc = (j - cy) / w * 2
    next_real = a ^ 2 - b ^ 2 + RealC
End Function

Function next_imaginary(a, b, i, j)
    RealC = (i - cx) / w * 2
    IMc = (j - cy) / w * 2
    next_imaginary = 2 * a * b + IMc
End Function

Private Sub Form_Load()
    Show
    w = Me.ScaleWidth
    h = Me.ScaleHeight
    cx = w / 2
    cy = h / 2

    For i = 0 To w
        For j = 0 To h
            RE = 0
            IM = 0
            iterations = 0
            While iterations < 20 And RE ^ 2 + IM ^ 2 < 4
                iterations = iterations + 1
                n_r = next_real(RE, IM, i, j)
                n_i = next_imaginary(RE, IM, i, j)
                RE = n_r
                IM = n_i
            Wend
            DoEvents
            My_Color = RGB(My_Red(iterations), My_Green(iterations), My_Blue(iterations))
            PSet (i, j), My_Color
        Next j
    Next i
End Sub