三角函數-繞圈應用

Public Class Form1
    Dim g As Graphics
    Dim x1, y1, x2, y2 As Single
    Dim r
    Dim angle
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        g = Me.CreateGraphics
        Me.BackColor = Color.White

        Timer1.Enabled = True
        Timer1.Interval = 100

        x1 = 300
        y1 = 300

        r = 200
        angle = 0
    End Sub

    Sub draw()
        g.DrawLine(Pens.Black, x1, y1, x2, y2)
    End Sub

    Sub drawWhite()
        g.DrawLine(Pens.White, x1, y1, x2, y2)
    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        drawWhite()
        angle = angle + 30
        x2 = 300 + r * Math.Cos(angle * 3.14 / 180) '弳度 = 角度 * 3.14/180
        y2 = 300 + r * Math.Sin(angle * 3.14 / 180)
        draw()
    End Sub
End Class