Fast filled circle

[dbox]

This has been tested and tested again, it uses 8 point octal calculations and holds up aginst memory techniques with even alpha shading (no overlapping), very fast and efficient.

Code: (Select All)

'from Steve "Gold standard"
Sub fcirc (CX As Long, CY As Long, R As Long, C As _Unsigned Long)
    Dim Radius As Long, RadiusError As Long
    Dim X As Long, Y As Long
    Radius = Abs(R): RadiusError = -Radius: X = Radius: Y = 0
    If Radius = 0 Then PSet (CX, CY), C: Exit Sub
    Line (CX - X, CY)-(CX + X, CY), C, BF
    While X > Y
        RadiusError = RadiusError + Y * 2 + 1
        If RadiusError >= 0 Then
            If X <> Y + 1 Then
                Line (CX - Y, CY - X)-(CX + Y, CY - X), C, BF
                Line (CX - Y, CY + X)-(CX + Y, CY + X), C, BF
            End If
            X = X - 1
            RadiusError = RadiusError - X * 2
        End If
        Y = Y + 1
        Line (CX - X, CY - Y)-(CX + X, CY - Y), C, BF
        Line (CX - X, CY + Y)-(CX + X, CY + Y), C, BF
    Wend
End Sub

Got it from Steve but he didn't invent it. fcirc is short for Filled Circle. The only place it doesn't work well is dbox's QBJS

Works fine if you comment out the unnecessary BF parameters:  View in QBJS