#pragma region CPL License
/*
Nuclex Native Framework
Copyright (C) 2002-2015 Nuclex Development Labs

This library is free software; you can redistribute it and/or
modify it under the terms of the IBM Common Public License as
published by the IBM Corporation; either version 1.0 of the
License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
IBM Common Public License for more details.

You should have received a copy of the IBM Common Public
License along with this library
*/
#pragma endregion // CPL License

#ifndef NUCLEX_GEOMETRY_LINES_TRACERS_RAY2TRACER_H
#define NUCLEX_GEOMETRY_LINES_TRACERS_RAY2TRACER_H

#include "Nuclex/Geometry/Config.h"
#include "Nuclex/Geometry/Lines/Line2.h"
#include "Nuclex/Geometry/Lines/Ray2.h"
#include "Nuclex/Geometry/LineContacts.h"

namespace Nuclex { namespace Geometry { namespace Lines { namespace Tracers {

  // ------------------------------------------------------------------------------------------- //

  /// <summary>Determines contacts between 2D lines and rays</summary>
  template <typename TScalar>
  class Ray2Tracer {

    /// <summary>Determines where a line crosses a ray</summary>
    /// <param name="line">Line whose time of crossing will be determined</param>
    /// <param name="ray">Ray that might be crossed</param>
    /// <returns>The time at which the line crosses the ray</returns>
    public: static LineContacts<TScalar> FindLineContacts(
      const Lines::Line2<TScalar> &line, const Lines::Ray2<TScalar> &ray
    ) {

      // Time of intersection of the segment with the traced line. This allows us to see
      // if the segment hits the traced line inside its length.
      TScalar s = (
        line.Direction.X * (line.Origin.Y - ray.Start.Y) -
        line.Direction.Y * (line.Origin.X - ray.Start.X)
      ) / (line.Direction.X * ray.Direction.Y - ray.Direction.X * line.Direction.Y);
      
      if(s >= 0) {
        TScalar t = (
          ray.Direction.X * (line.Origin.Y - ray.Start.Y) -
          ray.Direction.Y * (line.Origin.X - ray.Start.X)
        ) / (line.Direction.X * ray.Direction.Y - ray.Direction.X * line.Direction.Y);

        return LineContacts<TScalar>(t, t);
      } else {
        return LineContacts<TScalar>::None;
      }

    }

  };

  // ------------------------------------------------------------------------------------------- //

}}}} // namespace Nuclex::Geometry::Lines::Tracers

#endif // NUCLEX_GEOMETRY_LINES_TRACERS_RAY2TRACER_H