S.6　Cycloid類

　サイクロイドには、注目点と転円との位置関係で、低トロコイド、普通サイクロイド、高トロコイドがあります。一緒に図化したものです。

Public Sub Proc6() ' Cycloid
    Dim a, b, x, y, k, Th, p, Igra, iwidth
    Dim cx, cy, ctop, cbottom, cleft, cright
    Select Case Ivar
        Case 1: a = 40
        Case 2: a = 60
        Case 3: a = 80
        Case 4: a = 100
        Case Else: a = 40
    End Select
    Dperas
    cx = 240: cy = 120: Dpwind cx, cy, 640
    ctop = FormGraphic.Picture1.ScaleTop
    cbottom = FormGraphic.Picture1.ScaleHeight + ctop
    cleft = FormGraphic.Picture1.ScaleLeft
    cright = FormGraphic.Picture1.ScaleWidth + cleft
    Dpmove 0, ctop: Dpdraw 0, cbottom
    iwidth = FormGraphic.Picture1.DrawWidth   'save current value
    Dpensz 2
    Dpmove cleft, 0: Dpdraw cright, 0
    Dpensz iwidth                 'restore width
    Dpcirc 0, a, a
    Igra = 0: k = 32
    For p = 0.6 To 1.8 Step 0.4
        b = a * p
        For Th = -pie To 5 * pie Step pie / k
            x = a * Th - b * Sin(Th)
            y = a - b * Cos(Th)
            DrawPolyLine x, y, Igra
        Next Th
        Igra = 0
    Next p
    Dptext 80, 280, _
            ("a =" + CStr(a) + "; b=" + CStr(b))
End Sub