//-----------------------------------------------------------------------------
// Vector3Helper.cs
//
// Microsoft XNA Community Game Platform
// Copyright (C) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
using Microsoft.Xna.Framework;
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

namespace RacingGame.Helpers
{
    /// <summary>
    /// Vector 3 helper
    /// </summary>
    class Vector3Helper
    {
        /// <summary>
        /// Private constructor to prevent instantiation.
        /// </summary>
        private Vector3Helper()
        {
        }
        /// <summary>
        /// Return angle between two vectors. Used for visbility testing and
        /// for checking angles between vectors for the road sign generation.
        /// </summary>
        /// <param name="vec1">Vector 1</param>
        /// <param name="vec2">Vector 2</param>
        /// <returns>Float</returns>
        public static float GetAngleBetweenVectors(Vector3 vec1, Vector3 vec2)
        {
            // See http://en.wikipedia.org/wiki/Vector_(spatial)
            // for help and check out the Dot Product section ^^
            // Both vectors are normalized so we can save deviding through the
            // lengths.
            return (float)Math.Acos(Vector3.Dot(vec1, vec2));
        }
        /// <summary>
        /// Distance from our point to the line described by linePos1 and linePos2.
        /// </summary>
        /// <param name="point">Point</param>
        /// <param name="linePos1">Line position 1</param>
        /// <param name="linePos2">Line position 2</param>
        /// <returns>Float</returns>
        public static float DistanceToLine(Vector3 point,
            Vector3 linePos1, Vector3 linePos2)
        {
            // For help check out this article:
            // http://mathworld.wolfram.com/Point-LineDistance3-Dimensional.html
            Vector3 lineVec = linePos2 - linePos1;
            Vector3 pointVec = linePos1 - point;
            return Vector3.Cross(lineVec, pointVec).Length() / lineVec.Length();
        }
        /// <summary>
        /// Signed distance to plane
        /// </summary>
        /// <param name="point">Point</param>
        /// <param name="planePosition">Plane position</param>
        /// <param name="planeNormal">Plane normal</param>
        /// <returns>Float</returns>
        public static float SignedDistanceToPlane(Vector3 point,
            Vector3 planePosition, Vector3 planeNormal)
        {
            Vector3 pointVec = planePosition - point;
            return Vector3.Dot(planeNormal, pointVec);
        }
    }
}