' version 23-10-2016
' compile with: fbc -s console

Const scr_x = 800       ' screen 800 x 800
Const scr_y = 600
Const m_x = scr_x \ 2   ' middle of screen
Const m_y = scr_y \ 2


Sub superellipse(a As Long, b As Long, n As Double)

    ReDim As Long y(0 To a)
    Dim As Long x

    y(0) = b ' value for x = 0
    y(a) = 0 ' value for x = a

    '(0,0) is in upper left corner

    PSet (m_x, m_y - y(0)) ' set starting point

    For x = 1 To a-1
        y(x) = Int( Exp( Log(1 - ((x / a) ^ n)) / n ) * b )
        Line - ((m_x + x), (m_y - y(x)))
    Next

    For x = a To 0 Step -1
        Line - ((m_x + x), (m_y + y(x)))
    Next

    For x = 0 To a
        Line - ((m_x - x), (m_y + y(x)))
    Next

    For x = a To 0 Step -1
        Line - ((m_x - x), (m_y - y(x)))
    Next

End Sub

' ------=< MAIN >=------

ScreenRes scr_x, scr_y, 32

Dim As Long   a = 200
Dim As Long   b = 150
Dim As Double n = 2.5

superellipse(a, b, n)

' empty keyboard buffer
While Inkey <> "" : Wend
Print : Print "hit any key to end program"
Sleep
End