private IEnumerable <IWorld2DTile2D> TilesInRange(Circle2D circle)
{
for (var x = -circle.Radius; x < circle.Radius; x++)
{
for (var y = -circle.Radius; y < circle.Radius * 2; y++)
{
var point = circle.Origin + new Point2D(x, y);
if (circle.ContainsPoint(point))
{
yield return(new World2DTile2D(this[point], point, this));
}
}
}
}