/Rendering/Basics/Drawing/Line.cs

using System;

using Delta.Rendering.Cameras;

using Delta.Utilities.Datatypes;



namespace Delta.Rendering.Basics.Drawing

{

	/// <summary>

	/// Draw 2D or 3D lines with help of this class. Rarely used. If you want

	/// to render more complex shapes use one of the other classes here or

	/// implement one yourself. This has the advantage of optimizing it better.

	/// </summary>

	public static class Line

	{

		#region Draw (Static)

		/// <summary>

		/// Draw line in 2D

		/// </summary>

		/// <param name="startPosition">Start position in quadratic space.</param>

		/// <param name="endPosition">End position in quadratic space.</param>

		/// <param name="lineColor">Line color</param>

		public static void Draw(Point startPosition, Point endPosition,

			Color color)

		{

			#region Culling check

			// Skip if the line is certainly outside of the quadratic space.

			// Checking the screen area would work too, but is a little slower and

			// won't exclude much more anyway.

			float smallestX = startPosition.X < endPosition.X

			                  	? startPosition.X

			                  	: endPosition.X;

			float smallestY = startPosition.Y < endPosition.Y

			                  	? startPosition.Y

			                  	: endPosition.Y;

			float distanceX = Math.Abs(startPosition.X - endPosition.X);

			float distanceY = Math.Abs(startPosition.Y - endPosition.Y);

			if (smallestX >= 1.0f ||

			    smallestY >= 1.0f ||

			    smallestX < -distanceX ||

			    smallestY < -distanceY)

			{

				// Skip this line rendering, not visible this frame.

				WasLastLineCulled = true;

				return;

			}



			WasLastLineCulled = false;

			#endregion



			DrawManager.Instance.Draw2DLine(ref startPosition, ref endPosition,

				ref color);

		}

		#endregion



		#region DrawCross (Static)

		/// <summary>

		/// Draws a cross in 2D

		/// </summary>

		/// <param name="position">Position</param>

		/// <param name="radius">Radius</param>

		/// <param name="color">Color</param>

		public static void DrawCross(Point position, float radius, Color color)

		{

			Draw(new Point(position.X - radius, position.Y),

				new Point(position.X + radius, position.Y),

				color);



			Draw(new Point(position.X, position.Y - radius),

				new Point(position.X, position.Y + radius),

				color);

		}

		#endregion



		#region Draw (Static)

		/// <summary>

		/// Draw line in 3D

		/// </summary>

		/// <param name="startPosition">Start position</param>

		/// <param name="endPosition">End position</param>

		/// <param name="color">Line color</param>

		public static void Draw(Vector startPosition, Vector endPosition,

			Color color)

		{

			#region Culling check

			Plane[] frustum = BaseCamera.Current.ViewFrustum;

			// Check all the frustum planes.

			for (byte planeId = 0; planeId < 6; planeId++)

			{

				// is the positiveVertex outside?

				if (frustum[planeId].DotCoordinate(startPosition) < -0.001f &&

				    frustum[planeId].DotCoordinate(endPosition) < -0.001f)

				{

					WasLastLineCulled = true;

					return;

				}

			}



			WasLastLineCulled = false;

			#endregion



			DrawManager.Instance.Draw3DLine(ref startPosition, ref endPosition,

				ref color);

		}

		#endregion



		#region Internal



		#region WasLastLineCulled (Internal)

		/// <summary>

		/// Helper boolean for the Culling Draw Test which counts the

		/// number of drawn lines.

		/// </summary>

		internal static bool WasLastLineCulled;

		#endregion



		#endregion

	}

}