Imports System.Drawing.Bitmap
Imports System.Drawing.Imaging
'Option Strict On
Public Class Form1
    Private _width As Integer = 80
    Private _height As Integer = 120
    Private _files As Integer = 128
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim image1 As New Bitmap(_width, _height)
        Dim image2 As New Bitmap(_width, _height)
        Dim count As Integer = _files - 1
        Dim x, y As Integer
        Dim theta As Double = 0.0
        _initBar()
        Dim newColor As Color
        While count >= 0
            For x = 0 To image1.Width - 1
                For y = 0 To image1.Height - 1
                    newColor = _getCol(x, y, count, +1)
                    image1.SetPixel(x, y, newColor)
                    newColor = _getCol(x, y, count, -1)
                    image2.SetPixel(x, y, newColor)
                Next
            Next
            PictureBox1.Image = image1
            PictureBox2.Image = image2
            PictureBox1.Refresh()
            PictureBox2.Refresh()
            saveImage(count, image1, "l")
            saveImage(count, image2, "r")
            _setBar(_files - count)
            count = count - 1
        End While
        ProgressBar1.Value = 0
    End Sub
    Private Sub _initBar()
        ProgressBar1.Minimum = 0
        ProgressBar1.Maximum = _files
        ProgressBar1.Step = 1
    End Sub
    Private Sub _setBar(ByVal num As Integer)
        ProgressBar1.Value = num
    End Sub
    Private Sub saveImage(ByVal count As Integer, ByVal image As Bitmap, ByVal lr As String)
        Dim filename As String = TextBox1.Text & CStr(count) & "_" & lr & ".png"
        image.Save(filename, ImageFormat.Png)
        Console.WriteLine(filename + "を書き出し")
    End Sub
    Private Function _getCol(ByVal x As Integer, ByVal y As Integer, ByVal i As Integer, ByVal dir As Double) As Color
        Dim red As Double = 0
        Dim green As Double = 0
        Dim blue As Double = 0
        Dim speed As Double = 1.0
        Dim cx As Double = _width * 0.5
        Dim cy As Double = _height * 0.5
        Dim dx As Double = (x - cx)
        Dim dy As Double = (y - cy)
        Dim nx As Double
        Dim ny As Double
        Dim r As Double = Math.Sqrt(dx * dx + dy * dy)
        Dim theta As Double
        Dim bAll As Boolean = True
        Dim newColor As Color
        If r = 0 Then
            r = 0.1
        End If
		Dim rRatio As Double = Math.Max(0,0.07*speed*i*(1 - (Math.Sqrt(r/(cY*1.1))) ))
        Dim bInSide As Boolean = (r < cx And r < cy)
        If (Not bAll) And (Not bInSide) Then
            newColor = Color.FromArgb(0, 128, 128)
        Else
            theta = Math.Atan2(-dy, dx)
            nx = (cx + Math.Cos(theta - dir * rRatio) * r) - x
            ny = (cy - Math.Sin(theta - dir * rRatio) * r) - y
            blue = Math.Max(0, Math.Min(nx + 128, 255))
            green = Math.Max(0, Math.Min(ny + 128, 255))
            newColor = Color.FromArgb(CInt(red), CInt(green), CInt(blue))
        End If
        Return newColor
    End Function

End Class