/// <summary>
/// Creates a random simple polygon within the specified area.</summary>
/// <param name="x">
/// The smallest x-coordinate for any polygon vertex.</param>
/// <param name="y">
/// The smallest y-coordinate for any polygon vertex.</param>
/// <param name="width">
/// The width of the area containing all polygon vertices.</param>
/// <param name="height">
/// The height of the area containing all polygon vertices.</param>
/// <returns>
/// An <see cref="Array"/> containing the <see cref="PointD"/> coordinates that are the
/// vertices of the created polygon.</returns>
/// <exception cref="ArgumentOutOfRangeException">
/// <paramref name="width"/> or <paramref name="height"/> is equal to or less than zero.
/// </exception>
/// <remarks>
/// <b>RandomPolygon</b> moves in a full circle around the center of the specified area,
/// placing vertices at random angles and radii within the area. Any two vertices are
/// separated by a minimum angular distance of 6 degrees. The resulting polygon is simple,
/// i.e. covering a single contiguous space without self-intersections.</remarks>
public static PointD[] RandomPolygon(double x, double y, double width, double height)
{
if (width <= 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(
"width", width, Strings.ArgumentNotPositive);
}
if (height <= 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(
"height", height, Strings.ArgumentNotPositive);
}
// drawing range extending from center of drawing area
SizeD range = new SizeD(width / 2.0, height / 2.0);
PointD center = new PointD(x + range.Width, y + range.Height);
// radius of circle circumscribed around drawing area
double radius = Math.Sqrt(range.Width * range.Width + range.Height * range.Height);
// create vertices as series of random polar coordinates
var polygon = new List <PointD>();
for (double degrees = 0; degrees < 360; degrees += 6.0)
{
// random increment of angle for next vertex
degrees += MersenneTwister.Default.NextDouble() * 110;
if (degrees >= 360)
{
break;
}
double radians = degrees * Angle.DegreesToRadians;
// axis projections of circumscribed radius at current angle
double dx = Math.Cos(radians) * radius;
double dy = Math.Sin(radians) * radius;
// shorten total radius where it extends beyond area
double dxLimit = range.Width / Math.Abs(dx);
double dyLimit = range.Height / Math.Abs(dy);
double factor = Math.Min(dxLimit, dyLimit);
// additional random shortening to determine vertex
factor *= MersenneTwister.Default.NextDouble();
polygon.Add(new PointD(center.X + dx * factor, center.Y + dy * factor));
}
return(polygon.ToArray());
}
/// <summary>
/// Converts the specified <see cref="SizeD"/> to a WPF <see cref="Size"/>.</summary>
/// <param name="size">
/// The <see cref="SizeD"/> instance to convert.</param>
/// <returns>
/// A new WPF <see cref="Size"/> instance whose dimensions equal those of the specified
/// <paramref name="size"/>.</returns>
public static Size ToWpfSize(this SizeD size)
{
return(new Size(size.Width, size.Height));
}
