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/* ----------------------------------------------------------------------- *
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 * This file is part of GEL, http://www.imm.dtu.dk/GEL
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 * Copyright (C) the authors and DTU Informatics
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 * For license and list of authors, see ../../doc/intro.pdf
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 * ----------------------------------------------------------------------- */
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/** @file UnitVector.h
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 * @brief Unitvector coded with two angles - possibly not efficient.
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 */
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#ifndef __CGLA_UNITVECTOR_H__
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#define __CGLA_UNITVECTOR_H__
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#include "CGLA.h"
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#include "Vec3f.h"
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#include "TableTrigonometry.h"
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namespace CGLA
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{
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  namespace TT=TableTrigonometry;
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  /** \brief The UnitVector stores a unit length vector as two angles.
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  A vector stored as two (fix point) angles is much smaller than
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  vector stored in the usual way. On a 32 bit architecture this
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  class should take up four bytes. not too bad. */
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  class UnitVector
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    {
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      TT::Angle theta, phi;
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      void encode(const Vec3f& v)
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	{
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	  theta = TT::t_atan(std::sqrt(CGLA::sqr(v[0])+CGLA::sqr(v[1])), v[2]);
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	  phi   = TT::t_atan(v[0],v[1]);
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	}
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    public:
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      /// Construct unitvector from normal vector
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      explicit UnitVector(const Vec3f& v) {encode(v);}
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      /// Construct default unit vector
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      explicit UnitVector(): theta(0), phi(0) {}
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      /// Get theta angle
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      float t() const {return TT::angle2float(theta);}
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      /// Get phi angle
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      float f() const {return TT::angle2float(phi);}
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      /// Reconstruct Vec3f from unit vector
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      operator Vec3f() const
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	{
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	  float costf = TT::t_cos(theta);
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	  return Vec3f(TT::t_cos(phi)*costf ,
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		       TT::t_sin(phi)*costf,
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		       TT::t_sin(theta));
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	}
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      /// Test for equality.
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      bool operator==(const UnitVector& u) const
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	{
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	  return theta == u.theta && phi == u.phi;
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	}
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    };
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  /// Inline output operator.
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  inline std::ostream& operator<<(std::ostream& os, const UnitVector& u)
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    {
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      os << "<v=" << u.t() << " h=" << u.f() << ">";
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      return os;
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    }
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}
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#endif