public void DrawPolygon (Polygon poly, float w)
{
Write("<polygon stroke=\"{0}\" stroke-opacity=\"{1}\" stroke-width=\"{2}\" fill=\"none\" points=\"",
_lastColor,
_lastColorOp,
w);
foreach (var p in poly.Points) {
Write("{0}", p.X);
Write(",");
Write("{0}", p.Y);
Write(" ");
}
WriteLine("\" />");
}