'Sub Macro1()
'
' Macro1 Macro
'

'
'    Range("B1").Select
'End Sub

Option Base 1

Private Sub circlegen()

Dim r As Integer    'radius value
Dim xc As Integer   'circle center x value
Dim yc As Integer   'circle center y value
Dim x As Integer    'circle pixel x value
Dim y As Integer    'circle pixel y value
Dim d As Integer    'discriminant value for determining proximity to locus
Dim dtest As Integer
Dim i1 As Integer   'counter 1
Dim i2 As Integer   'counter 2
Dim iA As Integer   'circle coord array X coord element counter
Dim iB As Integer   'circle coord array Y coord element counter
Dim ar_oct_x()
Dim ar_oct_y()
Dim ar_circle()



'get seed values from input cells
r = Cells.Range("B1").Value
xc = Cells.Range("B2").Value
yc = Cells.Range("B3").Value


'populate seed octant x and y coordinate arrays
'plot first point for clockwise movement and d value
x = 0
y = r
d = (5 - (r * 4)) / 4

i1 = 1  'initialize counter 1
Do Until x > y 'when x > y, then the midpoint pixel shared by octants has been reached
    'populate array
        ReDim Preserve ar_oct_x(i1)
            ar_oct_x(i1) = x
        'y coord
        ReDim Preserve ar_oct_y(i1)
            ar_oct_y(i1) = y
        'increment counter
        i1 = i1 + 1

    x = x + 1
    If d < 0 Then
        d = d + (2 * x + 1)
    Else
        y = y - 1
        d = d + (2 * (x - y) + 1)
    End If
Loop

'populate final coordinate array with translated octant values
ReDim ar_circle(1 To 2, 1 To i1 * 8)

iA = 1
iB = 1
For i2 = 1 To UBound(ar_oct_x, 2)
    'cardinal coordinates
    If ar_oct_x(i2) = 0 Then
        'N
        ar_circle(iA, iB) = ar_oct_x(i2)
            iB = iB + 1
        ar_circle(iA, iB) = ar_oct_y(i2)
            iA = iA + 1
            iB = iB - 1
        'S
        ar_circle(iA, iB) = ar_oct_x(i2)
            iB = iB + 1
        ar_circle(iA, iB) = -(ar_oct_y(i2))
            iA = iA + 1
            iB = iB - 1
        'E
        ar_circle(iA, iB) = ar_oct_y(i2)
            iB = iB + 1
        ar_circle(iA, iB) = ar_oct_x(i2)
            iA = iA + 1
            iB = iB - 1
        'W
        ar_circle(iA, iB) = -(ar_oct_y(i2))
            iB = iB + 1
        ar_circle(iA, iB) = ar_oct_x(i2)
            iA = iA + 1
            iB = iB - 1
    End If

    'Ordinal coordinates
    If ar_oct_x(i2) = ar_oct_y(i2) Then

    End If
Next


dtest = 1

End Sub