// Project: XnaGraphicEngine, File: TangentVertex.cs
// Namespace: XnaGraphicEngine.Shaders, Class: 
// Path: C:\code\XnaGraphicEngine\Shaders, Author: Abi
// Code lines: 195, Size of file: 5,52 KB
// Creation date: 30.08.2006 11:38
// Last modified: 02.10.2006 06:18
// Generated with Commenter by abi.exDream.com

#region Using directives
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Graphics;
using System;
using System.Collections;
using System.Text;
using XnaGraphicEngine.Game;
#endregion

namespace XnaGraphicEngine.Shaders
{
	/// <summary>
	/// TangentVertex, extracted from Abi.Graphic engine for NormalMapCompressor.
	/// More information can be found at:
	/// http://exdream.dyn.ee/blog/PermaLink.aspx?guid=cd2c85b3-13e6-48cd-953e-f7e3bb79fbc5
	/// <para/>
	/// Tangent vertex format for shader vertex format used all over the place.
	/// DirectX9 or XNA does not provide this crazy format ^^ It contains:
	/// Position, Normal vector, texture coords, tangent vector.
	/// </summary>
	public struct TangentVertex
	{
		#region Variables
		/// <summary>
		/// Position
		/// </summary>
		public Vector3 pos;
		/// <summary>
		/// Texture coordinates
		/// </summary>
		public Vector2 uv;
		/// <summary>
		/// Normal
		/// </summary>
		public Vector3 normal;
		/// <summary>
		/// Tangent
		/// </summary>
		public Vector3 tangent;

		/*fixed number to prevent having us to use unsafe code
		/// <summary>
		/// Stride size, in XNA called SizeInBytes. I'm just conforming with that.
		/// Btw: How is this supposed to work without using unsafe AND
		/// without using System.Runtime.InteropServices.Marshal.SizeOf?
		/// </summary>
		public static unsafe int SizeInBytes
		{
			get
			{
				return (int)sizeof(TangentVertex);
			} // get
		} // StrideSize
		 */
		/// <summary>
		/// Stride size, in XNA called SizeInBytes. I'm just conforming with that.
		/// </summary>
		public static int SizeInBytes
		{
			get
			{
				// 4 bytes per float:
				// 3 floats pos, 2 floats uv, 3 floats normal and 3 float tangent.
				return 4 * (3 + 2 + 3 + 3);
			} // get
		} // StrideSize

		/// <summary>
		/// U texture coordinate
		/// </summary>
		/// <returns>Float</returns>
		public float U
		{
			get
			{
				return uv.X;
			} // get
		} // U

		/// <summary>
		/// V texture coordinate
		/// </summary>
		/// <returns>Float</returns>
		public float V
		{
			get
			{
				return uv.Y;
			} // get
		} // V
		#endregion

		#region Constructor
		/// <summary>
		/// Create tangent vertex
		/// </summary>
		/// <param name="setPos">Set position</param>
		/// <param name="setU">Set u texture coordinate</param>
		/// <param name="setV">Set v texture coordinate</param>
		/// <param name="setNormal">Set normal</param>
		/// <param name="setTangent">Set tangent</param>
		public TangentVertex(
			Vector3 setPos,
			float setU, float setV,
			Vector3 setNormal,
			Vector3 setTangent)
		{
			pos = setPos;
			uv = new Vector2(setU, setV);
			normal = setNormal;
			tangent = setTangent;
		} // TangentVertex(setPos, setU, setV)

		/// <summary>
		/// Create tangent vertex
		/// </summary>
		/// <param name="setPos">Set position</param>
		/// <param name="setUv">Set uv texture coordinates</param>
		/// <param name="setNormal">Set normal</param>
		/// <param name="setTangent">Set tangent</param>
		public TangentVertex(
			Vector3 setPos,
			Vector2 setUv,
			Vector3 setNormal,
			Vector3 setTangent)
		{
			pos = setPos;
			uv = setUv;
			normal = setNormal;
			tangent = setTangent;
		} // TangentVertex(setPos, setUv, setNormal)
		#endregion

		#region To string
		/// <summary>
		/// To string
		/// </summary>
		public override string ToString()
		{
			return "TangentVertex(pos=" + pos + ", " +
				"u=" + uv.X + ", " +
				"v=" + uv.Y + ", " +
				"normal=" + normal + ", " +
				"tangent=" + tangent + ")";
		} // ToString()
		#endregion

		#region Generate vertex declaration
		/// <summary>
		/// Vertex elements for Mesh.Clone
		/// </summary>
		public static readonly VertexElement[] VertexElements =
			GenerateVertexElements();

		/// <summary>
		/// Vertex declaration for vertex buffers.
		/// </summary>
		public static VertexDeclaration VertexDeclaration =
			new VertexDeclaration(BaseGame.Device, VertexElements);

		/// <summary>
		/// Generate vertex declaration
		/// </summary>
		private static VertexElement[] GenerateVertexElements()
		{
			VertexElement[] decl = new VertexElement[]
				{
					// Construct new vertex declaration with tangent info
					// First the normal stuff (we should already have that)
					new VertexElement(0, 0, VertexElementFormat.Vector3,
						VertexElementMethod.Default, VertexElementUsage.Position, 0),
					new VertexElement(0, 12, VertexElementFormat.Vector2,
						VertexElementMethod.Default, VertexElementUsage.TextureCoordinate,
						0),
					new VertexElement(0, 20, VertexElementFormat.Vector3,
						VertexElementMethod.Default, VertexElementUsage.Normal, 0),
					// And now the tangent
					new VertexElement(0, 32, VertexElementFormat.Vector3,
						VertexElementMethod.Default, VertexElementUsage.Tangent, 0),
				};
			return decl;
		} // GenerateVertexElements()
		#endregion

		#region Is declaration tangent vertex declaration
		/// <summary>
		/// Returns true if declaration is tangent vertex declaration.
		/// </summary>
		public static bool IsTangentVertexDeclaration(
			VertexElement[] declaration)
		{
			return
				declaration.Length == 4 &&
				declaration[0].VertexElementUsage == VertexElementUsage.Position &&
				declaration[1].VertexElementUsage ==
				VertexElementUsage.TextureCoordinate &&
				declaration[2].VertexElementUsage == VertexElementUsage.Normal &&
				declaration[3].VertexElementUsage == VertexElementUsage.Tangent;
		} // IsTangentVertexDeclaration(declaration)
		#endregion
	} // struct TangentVertex
} // namespace XnaGraphicEngine.Shaders