/Utilities/Math/LinearSegment.cs

using Delta.Utilities.Datatypes;

using Delta.Utilities.Helpers;



namespace Delta.Utilities.Math

{

	/// <summary>

	/// The linear segment class that exposes the functionality of getting a

	/// linearly interpolated value from between Point "Start" and "End".

	/// Only used for the Graph class.

	/// </summary>

	public struct LinearSegment

	{

		#region Constants

		/// <summary>

		/// Zero segment with Point.Zero as Start and End points, used to mark

		/// unused segments.

		/// </summary>

		public static readonly LinearSegment Zero =

			new LinearSegment(Point.Zero, Point.Zero);

		#endregion



		#region Start (Public)

		/// <summary>

		/// Start

		/// </summary>

		public Point Start;

		#endregion



		#region End (Public)

		/// <summary>

		/// End

		/// </summary>

		public Point End;

		#endregion



		#region Constructors

		/// <summary>

		/// Create linear segment

		/// </summary>

		public LinearSegment(Point setStart, Point setEnd)

		{

			Start = setStart;

			End = setEnd;

		}

		#endregion



		#region op_Equality (Operator)

		/// <summary>

		/// Operator to check for equality

		/// </summary>

		/// <param name="a">First value of the comparison.</param>

		/// <param name="b">Second value of the comparison.</param>

		public static bool operator ==(LinearSegment a, LinearSegment b)

		{

			return b.Start == a.Start &&

			       b.End == a.End;

		}

		#endregion



		#region op_Inequality (Operator)

		/// <summary>

		/// Operator to check for inequality

		/// </summary>

		/// <param name="a">First value of the comparison.</param>

		/// <param name="b">Second value of the comparison.</param>

		public static bool operator !=(LinearSegment a, LinearSegment b)

		{

			return b.Start != a.Start ||

			       b.End != a.End;

		}

		#endregion



		#region GetValue (Public)

		/// <summary>

		/// Get value in segment at position "at" on the x-axis.

		/// </summary>

		public float GetValue(float at)

		{

			float remainingPart = at - Start.X;

			float percentage =

				MathHelper.Min(remainingPart / (End.X - Start.X), 1.0f);



			return Start.Y + (End.Y - Start.Y) * percentage;

		}

		#endregion



		#region GetHashCode (Public)

		/// <summary>

		/// GetHashCode

		/// </summary>

		public override int GetHashCode()

		{

			return Start.GetHashCode() ^ End.GetHashCode();

		}

		#endregion



		#region Equals (Public)

		/// <summary>

		/// Equals

		/// </summary>

		/// <param name="obj">Object</param>

		public override bool Equals(object obj)

		{

			return (obj is LinearSegment)

			       	? this == (LinearSegment)obj

			       	: base.Equals(obj);

		}

		#endregion

	}

}