Title  Draw a cycloid 
Keywords  cycloid, curve 
Categories  Graphics 


This cycloid is represented by the following parametric functions as t ranges from 0 to 14 * Pi.


' The parametric function X(t).
Private Function X(ByVal t As Single) As Single
X = 2000 * (27 * Cos(t) + 15 * Cos(t * 20 / 7)) / 42
End Function
' The parametric function Y(t).
Private Function Y(ByVal t As Single) As Single
Y = 2000 * (27 * Sin(t) + 15 * Sin(t * 20 / 7)) / 42
End Function


In the form's Paint event handler, the program calls the DrawCurve subroutine to connect points defined by these functions.


' Draw the curve on the form.
Private Sub DrawCurve(ByVal start_t As Single, ByVal stop_t _
As Single, ByVal dt As Single)
Dim cx As Single
Dim cy As Single
Dim t As Single
cx = ScaleLeft + ScaleWidth / 2
cy = ScaleTop + ScaleHeight / 2
Cls
CurrentX = cx + X(start_t)
CurrentY = cy + Y(start_t)
t = start_t + dt
Do While t < stop_t
Line (cx + X(t), cy + Y(t))
t = t + dt
Loop
Line (cx + X(stop_t), cy + Y(stop_t))
End Sub


Click here to compare this code to the version used for VB .NET.
See my book Visual Basic Graphics Programming for more information on drawing cycloids and other curves normally or transformed (stretched, squashed, or rotated).



