public void DrawFrustum ( BoundingFrustum frustum, Color color )
{
var points = frustum.GetCorners();
DrawLine( points[0], points[1], color );
DrawLine( points[1], points[2], color );
DrawLine( points[2], points[3], color );
DrawLine( points[3], points[0], color );
DrawLine( points[4], points[5], color );
DrawLine( points[5], points[6], color );
DrawLine( points[6], points[7], color );
DrawLine( points[7], points[4], color );
DrawLine( points[0], points[4], color );
DrawLine( points[1], points[5], color );
DrawLine( points[2], points[6], color );
DrawLine( points[3], points[7], color );
}