| Title | Draw a epitrochoid |
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| Keywords | epitrochoid, curve |
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| Categories | Graphics |
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The epitrochoid is represented by the following parametric functions as t ranges from 0 to 8 * Pi.
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' The parametric function X(t).
Private Function X(ByVal t As Single) As Single
X = 8 * Cos(t / 4) - 7 * Cos(t)
End Function
' The parametric function Y(t).
Private Function Y(ByVal t As Single) As Single
Y = 8 * Sin(t / 4) - 7 * Sin(t)
End Function
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In the form's Paint event handler, the program calls the DrawCurve subroutine to connect points defined by these functions.
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' Draw the curve on the form.
Private Sub DrawCurve(ByVal start_t As Single, ByVal stop_t _
As Single, ByVal dt As Single)
Dim t As Single
Cls
CurrentX = X(start_t)
CurrentY = Y(start_t)
t = start_t + dt
Do While t < stop_t
Line -(X(t), Y(t))
t = t + dt
Loop
Line -(X(stop_t), Y(stop_t))
End Sub
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See my book Visual Basic Graphics Programming for more information on drawing other interesting curves normally or transformed (stretched, squashed, or rotated).
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