static VertexFragment()
{
_ellipseSegments = new Vector2[ELLIPSE_SEGMENTS];
float angle = 0.0f, angleStep = (float)(MathHelper.Pi * 2 / (double)ELLIPSE_SEGMENTS);
for (int n = 0; n < ELLIPSE_SEGMENTS; ++n)
{
_ellipseSegments[n] = new Vector2((float)Math.Cos(angle), (float)Math.Sin(angle)) * Vector2.One.Half() + Vector2.One.Half();
angle += angleStep;
}
}