Keskustelu: Koodit: VB.NET: Cubic Interpolation

Public Class Form1
    Inherits System.Windows.Forms.Form

    Dim points(7) As Point

#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.
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        '
        'Form1
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(968, 798)
        Me.Name = "Form1"
        Me.Text = "Interpolation"

    End Sub

#End Region

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        points(0) = New Point(0, 400)
        points(1) = New Point(200, 300)
        points(2) = New Point(300, 100)
        points(3) = New Point(400, 250)
        points(4) = New Point(500, 350)
        points(5) = New Point(600, 100)
        points(6) = New Point(700, 300)
        points(7) = New Point(800, 200)
    End Sub

    Private Sub Form1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
        Dim last, uus As Point
        last = points(0)
        Dim i, a As Integer
        For a = 0 To points.Length - 1
            ' Markkerit
            e.Graphics.DrawEllipse(Pens.Red, points(a).X, points(a).Y, 10, 10)
            ' piirretään 100:aan kohtaan
            For i = 0 To 100
                ' Jos a on menossa yli taulukkoindeksin, järjestetään jokaiseen tilanteeseen sopiva käsittelijä
                If a = 0 Then
                    uus.Y = Cubic_Interpolate(Me.Height, Me.Height, points(a).Y, points(a + 1).Y, i / 100)
                ElseIf a = 1 Then
                    uus.Y = Cubic_Interpolate(Me.Height, points(a - 1).Y, points(a).Y, points(a + 1).Y, i / 100)
                ElseIf a = points.Length - 1 Then
                    uus.Y = Cubic_Interpolate(points(a - 2).Y, points(a - 1).Y, points(a).Y, Me.Height, i / 100)
                Else
                    uus.Y = Cubic_Interpolate(points(a - 2).Y, points(a - 1).Y, points(a).Y, points(a + 1).Y, i / 100)
                End If
                uus.X = last.X + 1
                e.Graphics.DrawLine(Pens.Black, last.X, last.Y, uus.X, uus.Y)
                last = uus
            Next
        Next
    End Sub

' interpolaation ydin. se ottaa 4 pistettä ja palauttaa kahden keskimmäisen pisteen välisen matkan kohdan korkeuden. x kertoo, mistä kohtaa väliä piste otetaan. x on väliltä 0 - 1.
' tätä kaavaa en ole siis itse keksinyt. Jos haluat tietää lisää googleta :D
Function Cubic_Interpolate(ByVal v0, ByVal v1, ByVal v2, ByVal v3, ByVal x) As Integer
        Dim P As Integer = (v3 - v2) - (v0 - v1)
        Dim Q As Integer = (v0 - v1) - P
        Dim R As Integer = v2 - v0
        Dim S As Integer = v1
        Return P * x ^ 3 + Q * x ^ 2 + R * x + S
    End Function
End Class