Drawing and Filling Circle and Polygon.

Question

I have searched about creating these but cannot understand properly. 
Let SetPixel(X,Y) be the function to set the pixel. I am working in unity3d for drawing on texture.
Allow time to reverse.

Answer 1

besides what Armin said
which setpixel function do you mean ?
the bitmap.setpixel or the Win32 setpixel ?
also why would you want it in vb when you don't plan to use vb ?
I am writing class library for unity3d in vb.net.
"SetPixel(x,y)" is just a procedure that sets pixel on (x,y). It is enough for drawing.
I am not dealing with color or anything. Just need to set pixels at right position.
I tried and found this: (It is to draw non-filled circle)
Public Function Apply(Texture As Texture2D) As Texture2D Implements Image.Appliments.Apply
Dim x0 As Integer = Me.X
Dim y0 As Integer = Me.Y
Dim x As Integer = Radius
Dim y As Integer = 20
Dim RadiusError As Integer = 1 - x
While x >= y
Texture.SetPixel(x + x0, y + y0, Color)
Texture.SetPixel(y + x0, x + y0, Color)
Texture.SetPixel(-x + x0, y + y0, Color)
Texture.SetPixel(-y + x0, x + y0, Color)
Texture.SetPixel(-x + x0, -y + y0, Color)
Texture.SetPixel(-y + x0, -x + y0, Color)
Texture.SetPixel(x + x0, -y + y0, Color)
Texture.SetPixel(y + x0, -x + y0, Color)
y = y + 1
If RadiusError < 0 Then
RadiusError = RadiusError + 2 * y + 1
Else
x = x - 1
RadiusError = RadiusError + 2 * (y - x) + 1
End If
End While
Texture.Apply()
Return Texture
End Function
Allow time to reverse.