Keskustelu: Koodit: VB.NET: Noise-algoritmi

Public Class frmNoise
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call

    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.
    'Do not modify it using the code editor.
    Friend WithEvents picSurface As System.Windows.Forms.PictureBox
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.picSurface = New System.Windows.Forms.PictureBox
        Me.SuspendLayout()
        '
        'picSurface
        '
        Me.picSurface.Location = New System.Drawing.Point(0, 0)
        Me.picSurface.Name = "picSurface"
        Me.picSurface.Size = New System.Drawing.Size(464, 416)
        Me.picSurface.TabIndex = 0
        Me.picSurface.TabStop = False
        '
        'frmNoise
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(464, 414)
        Me.Controls.Add(Me.picSurface)
        Me.Name = "frmNoise"
        Me.Text = "Noise"
        Me.ResumeLayout(False)

    End Sub

#End Region

    Dim b As Bitmap
    Dim _Random() As Double

    Private Sub Ran()
        ' tehdään random lukuja sisältävä taulukko
        Dim r As New Random
        Dim i As Integer
        ReDim _Random(picSurface.Width * picSurface.Height)
        For i = 0 To picSurface.Width * picSurface.Height
            _Random(i) = r.NextDouble()
        Next
    End Sub

    Private Sub frmNoise_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim x, y, i As Integer
        Dim r As New Random
        Dim N As Double = 0.0
        b = New Bitmap(picSurface.Width, picSurface.Height)
        Ran()
        For y = 1 To picSurface.Height - 1
            For x = 1 To picSurface.Width - 1
                N = 0
                ' lisäilemällä ja poistelemalla näitä rivejä voidaan muuttaa melun näköä
                ' esim.
                ' kommentoi seuraavasta kaikki muut, paitsi ensimmäinen rivi
                ' muuta myös rivi N /= 6.0 ==> N /= 1.0 (jotta keskiarvo säilyisi)
                N += GetColor(x, y, 40 / 1)
                N += GetColor(x, y, 40 / 2)
                N += GetColor(x, y, 40 / 4)
                N += GetColor(x, y, 40 / 8)
                N += GetColor(x, y, 40 / 16)
                N += GetColor(x, y, 40 / 32)
                '-------------------------------------------------------
                N /= 6.0
                b.SetPixel(x, y, Color.FromArgb(0, 0, N * 255))
            Next
        Next
        picSurface.BackgroundImage = b
    End Sub

    Private Function GetColor(ByVal x As Integer, ByVal y As Integer, ByVal M As Integer) As Double
        Dim x0 As Integer = x - (x Mod M)
        Dim x1 As Integer = x0 + M
        Dim y0 As Integer = y - (y Mod M)
        Dim y1 As Integer = y0 + M

        ' melua talteen =)
        Dim x0y0 As Double = Noise(x0, y0)
        Dim x1y0 As Double = Noise(x1, y0)
        Dim x0y1 As Double = Noise(x0, y1)
        Dim x1y1 As Double = Noise(x1, y1)

        ' interpoloidaan(meniköhän tuo taivutus oikein?)
        Dim xx0 As Double = f(x0, x0y0, x1, x1y0, x)
        Dim xx1 As Double = f(x0, x0y1, x1, x1y1, x)

        Dim N As Double = f(y0, xx0, y1, xx1, y)
        Return N
    End Function

    Private Function Noise(ByVal x As Integer, ByVal y As Integer) As Double
        ' melua
        If (x < picSurface.Width And y < picSurface.Height) Then
            Return _Random(y * picSurface.Width + x)
        Else
            Return 0.0
        End If
    End Function

    Private Function f(ByVal x0 As Double, ByVal y0 As Double, ByVal x1 As Double, ByVal y1 As Double, ByVal x As Double) As Double
        ' Tämä saadaan vaikeasta yhtälöstä, jota en ole itse keksinyt. Ylistäkää Googlea!
        Return (1.0 + Math.Cos(Math.PI + (Math.PI / (x1 - x0)) * (x - x0))) / 2.0 * (y1 - y0) + y0
    End Function
End Class