#region --- License ---
/* Copyright (c) 2006, 2007 Stefanos Apostolopoulos
 * Contributions by Andy Gill.
 * See license.txt for license info
 */
#endregion

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;

namespace OpenTK.Math
{
    /// <summary>
    /// Represents a four-dimensional vector.
    /// </summary>
    [StructLayout(LayoutKind.Sequential)]
    public struct Vector4
    {
        #region Fields

        /// <summary>
        /// The X component of the Vector4.
        /// </summary>
        public float X;

        /// <summary>
        /// The Y component of the Vector4.
        /// </summary>
        public float Y;

        /// <summary>
        /// The Z component of the Vector4.
        /// </summary>
        public float Z;

        /// <summary>
        /// The Z component of the Vector4.
        /// </summary>
        public float W;

		public static Vector4 UnitX = new Vector4(1, 0, 0, 0);
		public static Vector4 UnitY = new Vector4(0, 1, 0, 0);
		public static Vector4 UnitZ = new Vector4(0, 0, 1, 0);
		public static Vector4 UnitW = new Vector4(0, 0, 0, 1);
		public static Vector4 Zero = new Vector4(0, 0, 0, 0);

        #endregion

        #region Constructors

        /// <summary>
        /// Constructs a new Vector4.
        /// </summary>
        /// <param name="x">The x component of the Vector4.</param>
        /// <param name="y">The y component of the Vector4.</param>
        /// <param name="z">The z component of the Vector4.</param>
        /// <param name="w">The z component of the Vector4.</param>
        public Vector4(float x, float y, float z, float w)
        {
            X = x;
            Y = y;
            Z = z;
            W = w;
        }

        /// <summary>
        /// Constructs a new Vector4 from the given Vector2.
        /// </summary>
        /// <param name="v">The Vector2 to copy components from.</param>
        public Vector4(Vector2 v)
        {
            X = v.X;
            Y = v.Y;
            Z = 0.0f;
            W = 0.0f;
        }

        /// <summary>
        /// Constructs a new Vector4 from the given Vector3.
        /// </summary>
        /// <param name="v">The Vector3 to copy components from.</param>
        public Vector4(Vector3 v)
        {
            X = v.X;
            Y = v.Y;
            Z = v.Z;
            W = 0.0f;
        }

        /// <summary>
        /// Constructs a new Vector4 from the given Vector4.
        /// </summary>
        /// <param name="v">The Vector4 to copy components from.</param>
        public Vector4(Vector4 v)
        {
            X = v.X;
            Y = v.Y;
            Z = v.Z;
            W = v.W;
        }

        #endregion

        #region Functions

        #region public float Length

        /// <summary>
        /// Gets the length (magnitude) of the vector.
        /// </summary>
        /// <see cref="FastLength"/>
        /// <seealso cref="LengthSquared"/>
        public float Length
        {
            get
            {
                return (float)System.Math.Sqrt(X * X + Y * Y + Z * Z + W * W);
            }
        }

        #endregion

        #region public float LengthFast

        /// <summary>
        /// Gets an approximation of the vector length (magnitude).
        /// </summary>
        /// <remarks>
        /// This property uses an approximation of the square root function to calculate vector magnitude, with
        /// an upper error bound of 0.001.
        /// </remarks>
        /// <see cref="Length"/>
        /// <seealso cref="LengthSquared"/>
        /// <seealso cref="OpenTK.Math.FastSqrt"/>
        public float LengthFast
        {
            get
            {
                return 1.0f / OpenTK.Math.Functions.InverseSqrtFast(X * X + Y * Y + Z * Z + W * W);
            }
        }

        #endregion

        #region public float LengthSquared

        /// <summary>
        /// Gets the square of the vector length (magnitude).
        /// </summary>
        /// <remarks>
        /// This property avoids the costly square root operation required by the Length property. This makes it more suitable
        /// for comparisons.
        /// </remarks>
        /// <see cref="Length"/>
        /// <seealso cref="FastLength"/>
        public float LengthSquared
        {
            get
            {
                return X * X + Y * Y + Z * Z + W * W;
            }
        }

        #endregion

        #region public void Normalize()

        /// <summary>
        /// Scales the Vector4 to unit length.
        /// </summary>
        public void Normalize()
        {
            float scale = 1.0f / this.Length;
            X *= scale;
            Y *= scale;
            Z *= scale;
            W *= scale;
        }

        #endregion

        #region public void NormalizeFast()

        /// <summary>
        /// Scales the Vector4 to approximately unit length.
        /// </summary>
        public void NormalizeFast()
        {
            float scale = Functions.InverseSqrtFast(X * X + Y * Y + Z * Z + W * W);
            X *= scale;
            Y *= scale;
            Z *= scale;
            W *= scale;
        }

        #endregion

        #region public void Scale(float sx, float sy, float sz, float sw)

        /// <summary>
        /// Scales the current Vector4 by the given amounts.
        /// </summary>
        /// <param name="sx">The scale of the X component.</param>
        /// <param name="sy">The scale of the Y component.</param>
        /// <param name="sz">The scale of the Z component.</param>
        /// <param name="sw">The scale of the Z component.</param>
        public void Scale(float sx, float sy, float sz, float sw)
        {
            this.X = X * sx;
            this.Y = Y * sy;
            this.Z = Z * sz;
            this.W = W * sw;
       }

        #endregion

        #endregion

        #region Operator overloads

        public static Vector4 operator +(Vector4 left, Vector4 right)
        {
			left.X += right.X;
			left.Y += right.Y;
			left.Z += right.Z;
			left.W += right.W;
			return left;
        }

        public static Vector4 operator -(Vector4 left, Vector4 right)
        {
			left.X -= right.X;
			left.Y -= right.Y;
			left.Z -= right.Z;
			left.W -= right.W;
			return left;
        }

		public static Vector4 operator -(Vector4 vec)
		{
			vec.X = -vec.X;
			vec.Y = -vec.Y;
			vec.Z = -vec.Z;
			vec.W = -vec.W;
			return vec;
		}

		public static Vector4 operator *(Vector4 vec, float f)
		{
			vec.X *= f;
			vec.Y *= f;
			vec.Z *= f;
			vec.W *= f;
			return vec;
		}

		public static Vector4 operator *(float f, Vector4 vec)
		{
			vec.X *= f;
			vec.Y *= f;
			vec.Z *= f;
			vec.W *= f;
			return vec;
		}

		public static Vector4 operator /(Vector4 vec, float f)
		{
			float mult = 1.0f / f;
			vec.X *= mult;
			vec.Y *= mult;
			vec.Z *= mult;
			vec.W *= mult;
			return vec;
		}

        [CLSCompliant(false)]
        unsafe public static explicit operator float*(Vector4 v)
        {
            return &v.X;
        }

        public static explicit operator IntPtr(Vector4 v)
        {
            unsafe
            {
                return (IntPtr)(&v.X);
            }
        }

        #endregion

		#region Static functions

		#region Add

		/// <summary>
		/// Add two Vectors
		/// </summary>
		/// <param name="a">First operand</param>
		/// <param name="b">Second operand</param>
		/// <returns>Result of addition</returns>
		public static Vector4 Add(Vector4 a, Vector4 b)
		{
			a.X += b.X;
			a.Y += b.Y;
			a.Z += b.Z;
			a.W += b.W;
			return a;
		}
	
		/// <summary>
		/// Add two Vectors
		/// </summary>
		/// <param name="a">First operand</param>
		/// <param name="b">Second operand</param>
		/// <param name="result">Result of addition</param>
		public static void Add(ref Vector4 a, ref Vector4 b, out Vector4 result)
		{
			result.X = a.X + b.X;
			result.Y = a.Y + b.Y;
			result.Z = a.Z + b.Z;
			result.W = a.W + b.W;
		}

		#endregion

		#region Sub

		/// <summary>
		/// Subtract one Vector from another
		/// </summary>
		/// <param name="a">First operand</param>
		/// <param name="b">Second operand</param>
		/// <returns>Result of subtraction</returns>
		public static Vector4 Sub(Vector4 a, Vector4 b)
		{
			a.X -= b.X;
			a.Y -= b.Y;
			a.Z -= b.Z;
			a.W -= b.W;
			return a;
		}

		/// <summary>
		/// Subtract one Vector from another
		/// </summary>
		/// <param name="a">First operand</param>
		/// <param name="b">Second operand</param>
		/// <param name="result">Result of subtraction</param>
		public static void Sub(ref Vector4 a, ref Vector4 b, out Vector4 result)
		{
			result.X = a.X - b.X;
			result.Y = a.Y - b.Y;
			result.Z = a.Z - b.Z;
			result.W = a.W - b.W;
		}

		#endregion

		#region Mult

		/// <summary>
		/// Multiply a vector and a scalar
		/// </summary>
		/// <param name="a">Vector operand</param>
		/// <param name="f">Scalar operand</param>
		/// <returns>Result of the multiplication</returns>
		public static Vector4 Mult(Vector4 a, float f)
		{
			a.X *= f;
			a.Y *= f;
			a.Z *= f;
			a.W *= f;
			return a;
		}

		/// <summary>
		/// Multiply a vector and a scalar
		/// </summary>
		/// <param name="a">Vector operand</param>
		/// <param name="f">Scalar operand</param>
		/// <param name="result">Result of the multiplication</param>
		public static void Mult(ref Vector4 a, float f, out Vector4 result)
		{
			result.X = a.X * f;
			result.Y = a.Y * f;
			result.Z = a.Z * f;
			result.W = a.W * f;
		}

		#endregion

		#region Div

		/// <summary>
		/// Divide a vector by a scalar
		/// </summary>
		/// <param name="a">Vector operand</param>
		/// <param name="f">Scalar operand</param>
		/// <returns>Result of the division</returns>
		public static Vector4 Div(Vector4 a, float f)
		{
			float mult = 1.0f / f;
			a.X *= mult;
			a.Y *= mult;
			a.Z *= mult;
			a.W *= mult;
			return a;
		}

		/// <summary>
		/// Divide a vector by a scalar
		/// </summary>
		/// <param name="a">Vector operand</param>
		/// <param name="f">Scalar operand</param>
		/// <param name="result">Result of the division</param>
		public static void Div(ref Vector4 a, float f, out Vector4 result)
		{
			float mult = 1.0f / f;
			result.X = a.X * mult;
			result.Y = a.Y * mult;
			result.Z = a.Z * mult;
			result.W = a.W * mult;
		}

		#endregion

		#region Min

		/// <summary>
		/// Calculate the component-wise minimum of two vectors
		/// </summary>
		/// <param name="a">First operand</param>
		/// <param name="b">Second operand</param>
		/// <returns>The component-wise minimum</returns>
		public static Vector4 Min(Vector4 a, Vector4 b)
		{
			a.X = a.X < b.X ? a.X : b.X;
			a.Y = a.Y < b.Y ? a.Y : b.Y;
			a.Z = a.Z < b.Z ? a.Z : b.Z;
			a.W = a.W < b.W ? a.W : b.W;
			return a;
		}

		/// <summary>
		/// Calculate the component-wise minimum of two vectors
		/// </summary>
		/// <param name="a">First operand</param>
		/// <param name="b">Second operand</param>
		/// <param name="result">The component-wise minimum</param>
		public static void Min(ref Vector4 a, ref Vector4 b, out Vector4 result)
		{
			result.X = a.X < b.X ? a.X : b.X;
			result.Y = a.Y < b.Y ? a.Y : b.Y;
			result.Z = a.Z < b.Z ? a.Z : b.Z;
			result.W = a.W < b.W ? a.W : b.W;
		}

		#endregion

		#region Max

		/// <summary>
		/// Calculate the component-wise maximum of two vectors
		/// </summary>
		/// <param name="a">First operand</param>
		/// <param name="b">Second operand</param>
		/// <returns>The component-wise maximum</returns>
		public static Vector4 Max(Vector4 a, Vector4 b)
		{
			a.X = a.X > b.X ? a.X : b.X;
			a.Y = a.Y > b.Y ? a.Y : b.Y;
			a.Z = a.Z > b.Z ? a.Z : b.Z;
			a.W = a.W > b.W ? a.W : b.W;
			return a;
		}

		/// <summary>
		/// Calculate the component-wise maximum of two vectors
		/// </summary>
		/// <param name="a">First operand</param>
		/// <param name="b">Second operand</param>
		/// <param name="result">The component-wise maximum</param>
		public static void Max(ref Vector4 a, ref Vector4 b, out Vector4 result)
		{
			result.X = a.X > b.X ? a.X : b.X;
			result.Y = a.Y > b.Y ? a.Y : b.Y;
			result.Z = a.Z > b.Z ? a.Z : b.Z;
			result.W = a.W > b.W ? a.W : b.W;
		}

		#endregion

		#region Clamp

		/// <summary>
		/// Clamp a vector to the given minimum and maximum vectors
		/// </summary>
		/// <param name="vec">Input vector</param>
		/// <param name="min">Minimum vector</param>
		/// <param name="max">Maximum vector</param>
		/// <returns>The clamped vector</returns>
		public static Vector4 Clamp(Vector4 vec, Vector4 min, Vector4 max)
		{
			vec.X = vec.X < min.X ? min.X : vec.X > max.X ? max.X : vec.X;
			vec.Y = vec.Y < min.Y ? min.Y : vec.Y > max.Y ? max.Y : vec.Y;
			vec.Z = vec.X < min.Z ? min.Z : vec.Z > max.Z ? max.Z : vec.Z;
			vec.W = vec.Y < min.W ? min.W : vec.W > max.W ? max.W : vec.W;
			return vec;
		}

		/// <summary>
		/// Clamp a vector to the given minimum and maximum vectors
		/// </summary>
		/// <param name="vec">Input vector</param>
		/// <param name="min">Minimum vector</param>
		/// <param name="max">Maximum vector</param>
		/// <param name="result">The clamped vector</param>
		public static void Clamp(ref Vector4 vec, ref Vector4 min, ref Vector4 max, out Vector4 result)
		{
			result.X = vec.X < min.X ? min.X : vec.X > max.X ? max.X : vec.X;
			result.Y = vec.Y < min.Y ? min.Y : vec.Y > max.Y ? max.Y : vec.Y;
			result.Z = vec.X < min.Z ? min.Z : vec.Z > max.Z ? max.Z : vec.Z;
			result.W = vec.Y < min.W ? min.W : vec.W > max.W ? max.W : vec.W;
		}

		#endregion

		#region Normalize

		/// <summary>
		/// Scale a vector to unit length
		/// </summary>
		/// <param name="vec">The input vector</param>
		/// <returns>The normalized vector</returns>
		public static Vector4 Normalize(Vector4 vec)
		{
			float scale = 1.0f / vec.Length;
			vec.X *= scale;
			vec.Y *= scale;
			vec.Z *= scale;
			vec.W *= scale;
			return vec;
		}

		/// <summary>
		/// Scale a vector to unit length
		/// </summary>
		/// <param name="vec">The input vector</param>
		/// <param name="result">The normalized vector</param>
		public static void Normalize(ref Vector4 vec, out Vector4 result)
		{
			float scale = 1.0f / vec.Length;
			result.X = vec.X * scale;
			result.Y = vec.Y * scale;
			result.Z = vec.Z * scale;
			result.W = vec.W * scale;
		}

		#endregion

		#region NormalizeFast

		/// <summary>
		/// Scale a vector to approximately unit length
		/// </summary>
		/// <param name="vec">The input vector</param>
		/// <returns>The normalized vector</returns>
		public static Vector4 NormalizeFast(Vector4 vec)
		{
			float scale = Functions.InverseSqrtFast(vec.X * vec.X + vec.Y * vec.Y + vec.Z * vec.Z + vec.W * vec.W);
			vec.X *= scale;
			vec.Y *= scale;
			vec.Z *= scale;
			vec.W *= scale;
			return vec;
		}

		/// <summary>
		/// Scale a vector to approximately unit length
		/// </summary>
		/// <param name="vec">The input vector</param>
		/// <param name="result">The normalized vector</param>
		public static void NormalizeFast(ref Vector4 vec, out Vector4 result)
		{
			float scale = Functions.InverseSqrtFast(vec.X * vec.X + vec.Y * vec.Y + vec.Z * vec.Z + vec.W * vec.W);
			result.X = vec.X * scale;
			result.Y = vec.Y * scale;
			result.Z = vec.Z * scale;
			result.W = vec.W * scale;
		}

		#endregion

		#region Dot

		/// <summary>
		/// Caclulate the dot product of two vectors
		/// </summary>
		/// <param name="left">First operand</param>
		/// <param name="right">Second operand</param>
		/// <returns>The dot product of the two inputs</returns>
		public static float Dot(Vector4 left, Vector4 right)
		{
			return left.X * right.X + left.Y * right.Y + left.Z * right.Z + left.W * right.W;
		}

		#endregion

		#region Lerp

		/// <summary>
		/// Returns a new Vector that is the linear blend of the 2 given Vectors
		/// </summary>
		/// <param name="a">First input vector</param>
		/// <param name="b">Second input vector</param>
		/// <param name="blend">The blend factor</param>
		/// <returns>a when blend=0, b when blend=1, and a linear combination otherwise</returns>
		public static Vector4 Lerp(Vector4 a, Vector4 b, float blend)
		{
			a.X = blend * (b.X - a.X) + a.X;
			a.Y = blend * (b.Y - a.Y) + a.Y;
			a.Z = blend * (b.Z - a.Z) + a.Z;
			a.W = blend * (b.W - a.W) + a.W;
			return a;
		}

		#endregion

		#region Barycentric

		/// <summary>
		/// Interpolate 3 Vectors using Barycentric coordinates
		/// </summary>
		/// <param name="a">First input Vector</param>
		/// <param name="b">Second input Vector</param>
		/// <param name="c">Third input Vector</param>
		/// <param name="u">First Barycentric Coordinate</param>
		/// <param name="v">Second Barycentric Coordinate</param>
		/// <returns>a when u=v=0, b when u=1,v=0, c when u=0,v=1, and a linear combination of a,b,c otherwise</returns>
		public static Vector4 BaryCentric(Vector4 a, Vector4 b, Vector4 c, float u, float v)
		{
			return a + u * (b - a) + v * (c - a);
		}

		#endregion

		#region Transform

		/// <summary>
		/// Transform a Vector by the given Matrix
		/// </summary>
		/// <param name="pos">The vector to transform</param>
		/// <param name="mat">The desired transformation</param>
		/// <returns>The transformed vector</returns>
		public static Vector4 Transform(Vector4 vec, Matrix4 mat)
		{
			Vector4 result;
			result.X = Vector4.Dot(vec, mat.Column0);
			result.Y = Vector4.Dot(vec, mat.Column1);
			result.Z = Vector4.Dot(vec, mat.Column2);
			result.W = Vector4.Dot(vec, mat.Column3);
			return result;
		}

		#endregion

		#endregion

		#region public override string ToString()

		/// <summary>
		/// Returns a System.String that represents the current Vector4.
		/// </summary>
		/// <returns></returns>
		public override string ToString()
        {
            return String.Format("({0}, {1}, {2}, {3})", X, Y, Z, W);
		}

		#endregion
	}
}