// Copyright (C) 2017 Jérôme Leclercq
// This file is part of the "Nazara Engine - Mathematics module"
// For conditions of distribution and use, see copyright notice in Config.hpp

// Sources:
// http://www.crownandcutlass.com/features/technicaldetails/frustum.html
// http://www.lighthouse3d.com/tutorials/view-frustum-culling/

#include <Nazara/Core/Algorithm.hpp>
#include <Nazara/Core/StringStream.hpp>
#include <Nazara/Math/Algorithm.hpp>
#include <cstring>
#include <Nazara/Core/Debug.hpp>

#define F(a) static_cast<T>(a)

namespace Nz
{

	/*!
    * \ingroup math
	* \class Nz::Frustum
	* \brief Math class that represents a frustum in the three dimensional vector space
	*
	* Frustums are used to determine what is inside the camera's field of view. They help speed up the rendering process
	*/

	/*!
	* \brief Constructs a Frustum object from another type of Frustum
	*
	* \param frustum Frustum of type U to convert to type T
	*/

	template<typename T>
	template<typename U>
	Frustum<T>::Frustum(const Frustum<U>& frustum)
	{
		Set(frustum);
	}

	/*!
	* \brief Builds the frustum object
	* \return A reference to this frustum which is the build up camera's field of view
	*
	* \param angle Unit depends on NAZARA_MATH_ANGLE_RADIAN
	* \param ratio Rendering ratio (typically 16/9 or 4/3)
	* \param zNear Distance where 'vision' begins
	* \param zFar Distance where 'vision' ends
	* \param eye Position of the camera
	* \param target Position of the target of the camera
	* \param up Direction of up vector according to the orientation of camera
	*/

	template<typename T>
	Frustum<T>& Frustum<T>::Build(T angle, T ratio, T zNear, T zFar, const Vector3<T>& eye, const Vector3<T>& target, const Vector3<T>& up)
	{
		#if NAZARA_MATH_ANGLE_RADIAN
		angle /= F(2.0);
		#else
		angle = DegreeToRadian(angle/F(2.0));
		#endif

		T tangent = std::tan(angle);
		T nearH = zNear * tangent;
		T nearW = nearH * ratio;
		T farH = zFar * tangent;
		T farW = farH * ratio;

		Vector3<T> f = Vector3<T>::Normalize(target - eye);
		Vector3<T> u(up.GetNormal());
		Vector3<T> s = Vector3<T>::Normalize(f.CrossProduct(u));
		u = s.CrossProduct(f);

		Vector3<T> nc = eye + f * zNear;
		Vector3<T> fc = eye + f * zFar;

		// Computing the frustum
		m_corners[BoxCorner_FarLeftBottom] = fc - u * farH - s * farW;
		m_corners[BoxCorner_FarLeftTop] = fc + u * farH - s * farW;
		m_corners[BoxCorner_FarRightTop] = fc + u * farH + s * farW;
		m_corners[BoxCorner_FarRightBottom] = fc - u * farH + s * farW;

		m_corners[BoxCorner_NearLeftBottom] = nc - u * nearH - s * nearW;
		m_corners[BoxCorner_NearLeftTop] = nc + u * nearH - s * nearW;
		m_corners[BoxCorner_NearRightTop] = nc + u * nearH + s * nearW;
		m_corners[BoxCorner_NearRightBottom] = nc - u * nearH + s * nearW;

		// Construction of frustum's planes
		m_planes[FrustumPlane_Bottom].Set(m_corners[BoxCorner_NearLeftBottom], m_corners[BoxCorner_NearRightBottom], m_corners[BoxCorner_FarRightBottom]);
		m_planes[FrustumPlane_Far].Set(m_corners[BoxCorner_FarRightTop], m_corners[BoxCorner_FarLeftTop], m_corners[BoxCorner_FarLeftBottom]);
		m_planes[FrustumPlane_Left].Set(m_corners[BoxCorner_NearLeftTop], m_corners[BoxCorner_NearLeftBottom], m_corners[BoxCorner_FarLeftBottom]);
		m_planes[FrustumPlane_Near].Set(m_corners[BoxCorner_NearLeftTop], m_corners[BoxCorner_NearRightTop], m_corners[BoxCorner_NearRightBottom]);
		m_planes[FrustumPlane_Right].Set(m_corners[BoxCorner_NearRightBottom], m_corners[BoxCorner_NearRightTop], m_corners[BoxCorner_FarRightBottom]);
		m_planes[FrustumPlane_Top].Set(m_corners[BoxCorner_NearRightTop], m_corners[BoxCorner_NearLeftTop], m_corners[BoxCorner_FarLeftTop]);

		return *this;
	}

	/*!
	* \brief Checks whether or not a bounding volume is contained in the frustum
	* \return true if the bounding volume is entirely in the frustum
	*
	* \param volume Volume to check
	*
	* \remark If volume is infinite, true is returned
	* \remark If volume is null, false is returned
	* \remark If enumeration of the volume is not defined in Extend, a NazaraError is thrown and false is returned
	* \remark If enumeration of the intersection is not defined in IntersectionSide, a NazaraError is thrown and false is returned. This should not never happen for a user of the library
	*/

	template<typename T>
	bool Frustum<T>::Contains(const BoundingVolume<T>& volume) const
	{
		switch (volume.extend)
		{
			case Extend_Finite:
			{
				IntersectionSide side = Intersect(volume.aabb);
				switch (side)
				{
					case IntersectionSide_Inside:
						return true;

					case IntersectionSide_Intersecting:
						return Contains(volume.obb);

					case IntersectionSide_Outside:
						return false;
				}

				NazaraError("Invalid intersection side (0x" + String::Number(side, 16) + ')');
				return false;
			}

			case Extend_Infinite:
				return true;

			case Extend_Null:
				return false;
		}

		NazaraError("Invalid extend type (0x" + String::Number(volume.extend, 16) + ')');
		return false;
	}

	/*!
	* \brief Checks whether or not a box is contained in the frustum
	* \return true if the box is entirely in the frustum
	*
	* \param box Box to check
	*/

	template<typename T>
	bool Frustum<T>::Contains(const Box<T>& box) const
	{
		// http://www.lighthouse3d.com/tutorials/view-frustum-culling/geometric-approach-testing-boxes-ii/
		for (unsigned int i = 0; i <= FrustumPlane_Max; i++)
		{
			if (m_planes[i].Distance(box.GetPositiveVertex(m_planes[i].normal)) < F(0.0))
				return false;
		}

		return true;
	}

	/*!
	* \brief Checks whether or not an oriented box is contained in the frustum
	* \return true if the oriented box is entirely in the frustum
	*
	* \param orientedbox Oriented box to check
	*/

	template<typename T>
	bool Frustum<T>::Contains(const OrientedBox<T>& orientedbox) const
	{
		return Contains(&orientedbox[0], 8);
	}

	/*!
	* \brief Checks whether or not a sphere is contained in the frustum
	* \return true if the sphere is entirely in the frustum
	*
	* \param sphere Sphere to check
	*/

	template<typename T>
	bool Frustum<T>::Contains(const Sphere<T>& sphere) const
	{
		for (unsigned int i = 0; i <= FrustumPlane_Max; i++)
		{
			if (m_planes[i].Distance(sphere.GetPosition()) < -sphere.radius)
				return false;
		}

		return true;
	}

	/*!
	* \brief Checks whether or not a Vector3 is contained in the frustum
	* \return true if the Vector3 is in the frustum
	*
	* \param point Vector3 which represents a point in the space
	*/

	template<typename T>
	bool Frustum<T>::Contains(const Vector3<T>& point) const
	{
		for (unsigned int i = 0; i <= FrustumPlane_Max; ++i)
		{
			if (m_planes[i].Distance(point) < F(0.0))
				return false;
		}

		return true;
	}

	/*!
	* \brief Checks whether or not a set of Vector3 is contained in the frustum
	* \return true if the set of Vector3 is in the frustum
	*
	* \param points Pointer to Vector3 which represents a set of points in the space
	* \param pointCount Number of points to check
	*/

	template<typename T>
	bool Frustum<T>::Contains(const Vector3<T>* points, unsigned int pointCount) const
	{
		for (unsigned int i = 0; i <= FrustumPlane_Max; ++i)
		{
			unsigned int j;
			for (j = 0; j < pointCount; j++ )
			{
				if (m_planes[i].Distance(points[j]) > F(0.0))
					break;
			}

			if (j == pointCount)
				return false;
		}

		return true;
	}

	/*!
	* \brief Constructs the frustum from a Matrix4
	* \return A reference to this frustum which is the build up of projective matrix
	*
	* \param clipMatrix Matrix which represents the transformation of the frustum
	*
	* \remark A NazaraWarning is produced if clipMatrix is not inversible and corners are unchanged
	*/

	template<typename T>
	Frustum<T>& Frustum<T>::Extract(const Matrix4<T>& clipMatrix)
	{
		// http://www.crownandcutlass.com/features/technicaldetails/frustum.html
		T plane[4];
		T invLength;

		// Extract the numbers for the RIGHT plane
		plane[0] = clipMatrix[ 3] - clipMatrix[ 0];
		plane[1] = clipMatrix[ 7] - clipMatrix[ 4];
		plane[2] = clipMatrix[11] - clipMatrix[ 8];
		plane[3] = clipMatrix[15] - clipMatrix[12];

		// Normalize the result
		invLength = F(1.0) / std::sqrt(plane[0] * plane[0] + plane[1] * plane[1] + plane[2] * plane[2]);
		plane[0] *= invLength;
		plane[1] *= invLength;
		plane[2] *= invLength;
		plane[3] *= -invLength;

		m_planes[FrustumPlane_Right].Set(plane);

		// Extract the numbers for the LEFT plane
		plane[0] = clipMatrix[ 3] + clipMatrix[ 0];
		plane[1] = clipMatrix[ 7] + clipMatrix[ 4];
		plane[2] = clipMatrix[11] + clipMatrix[ 8];
		plane[3] = clipMatrix[15] + clipMatrix[12];

		// Normalize the result
		invLength = F(1.0) / std::sqrt(plane[0] * plane[0] + plane[1] * plane[1] + plane[2] * plane[2]);
		plane[0] *= invLength;
		plane[1] *= invLength;
		plane[2] *= invLength;
		plane[3] *= -invLength;

		m_planes[FrustumPlane_Left].Set(plane);

		// Extract the BOTTOM plane
		plane[0] = clipMatrix[ 3] + clipMatrix[ 1];
		plane[1] = clipMatrix[ 7] + clipMatrix[ 5];
		plane[2] = clipMatrix[11] + clipMatrix[ 9];
		plane[3] = clipMatrix[15] + clipMatrix[13];

		// Normalize the result
		invLength = F(1.0) / std::sqrt(plane[0] * plane[0] + plane[1] * plane[1] + plane[2] * plane[2]);
		plane[0] *= invLength;
		plane[1] *= invLength;
		plane[2] *= invLength;
		plane[3] *= -invLength;

		m_planes[FrustumPlane_Bottom].Set(plane);

		// Extract the TOP plane
		plane[0] = clipMatrix[ 3] - clipMatrix[ 1];
		plane[1] = clipMatrix[ 7] - clipMatrix[ 5];
		plane[2] = clipMatrix[11] - clipMatrix[ 9];
		plane[3] = clipMatrix[15] - clipMatrix[13];

		// Normalize the result
		invLength = F(1.0) / std::sqrt(plane[0] * plane[0] + plane[1] * plane[1] + plane[2] * plane[2]);
		plane[0] *= invLength;
		plane[1] *= invLength;
		plane[2] *= invLength;
		plane[3] *= -invLength;

		m_planes[FrustumPlane_Top].Set(plane);

		// Extract the FAR plane
		plane[0] = clipMatrix[ 3] - clipMatrix[ 2];
		plane[1] = clipMatrix[ 7] - clipMatrix[ 6];
		plane[2] = clipMatrix[11] - clipMatrix[10];
		plane[3] = clipMatrix[15] - clipMatrix[14];

		// Normalize the result
		invLength = F(1.0) / std::sqrt(plane[0] * plane[0] + plane[1] * plane[1] + plane[2] * plane[2]);
		plane[0] *= invLength;
		plane[1] *= invLength;
		plane[2] *= invLength;
		plane[3] *= -invLength;

		m_planes[FrustumPlane_Far].Set(plane);

		// Extract the NEAR plane
		plane[0] = clipMatrix[ 3] + clipMatrix[ 2];
		plane[1] = clipMatrix[ 7] + clipMatrix[ 6];
		plane[2] = clipMatrix[11] + clipMatrix[10];
		plane[3] = clipMatrix[15] + clipMatrix[14];

		// Normalize the result
		invLength = F(1.0) / std::sqrt(plane[0] * plane[0] + plane[1] * plane[1] + plane[2] * plane[2]);
		plane[0] *= invLength;
		plane[1] *= invLength;
		plane[2] *= invLength;
		plane[3] *= -invLength;

		m_planes[FrustumPlane_Near].Set(plane);

		// Once planes have been extracted, we must extract points of the frustum
		// Based on: http://www.gamedev.net/topic/393309-calculating-the-view-frustums-vertices/

		Matrix4<T> invClipMatrix;
		if (clipMatrix.GetInverse(&invClipMatrix))
		{
			Vector4<T> corner;

			// FarLeftBottom
			corner.Set(F(-1.0), F(-1.0), F(1.0));
			corner = invClipMatrix.Transform(corner);
			corner.Normalize();

			m_corners[BoxCorner_FarLeftBottom] = Vector3<T>(corner.x, corner.y, corner.z);

			// FarLeftTop
			corner.Set(F(-1.0), F(1.0), F(1.0));
			corner = invClipMatrix.Transform(corner);
			corner.Normalize();

			m_corners[BoxCorner_FarLeftTop] = Vector3<T>(corner.x, corner.y, corner.z);

			// FarRightBottom
			corner.Set(F(1.0), F(-1.0), F(1.0));
			corner = invClipMatrix.Transform(corner);
			corner.Normalize();

			m_corners[BoxCorner_FarRightBottom] = Vector3<T>(corner.x, corner.y, corner.z);

			// FarRightTop
			corner.Set(F(1.0), F(1.0), F(1.0));
			corner = invClipMatrix.Transform(corner);
			corner.Normalize();

			m_corners[BoxCorner_FarRightTop] = Vector3<T>(corner.x, corner.y, corner.z);

			// NearLeftBottom
			corner.Set(F(-1.0), F(-1.0), F(0.0));
			corner = invClipMatrix.Transform(corner);
			corner.Normalize();

			m_corners[BoxCorner_NearLeftBottom] = Vector3<T>(corner.x, corner.y, corner.z);

			// NearLeftTop
			corner.Set(F(-1.0), F(1.0), F(0.0));
			corner = invClipMatrix.Transform(corner);
			corner.Normalize();

			m_corners[BoxCorner_NearLeftTop] = Vector3<T>(corner.x, corner.y, corner.z);

			// NearRightBottom
			corner.Set(F(1.0), F(-1.0), F(0.0));
			corner = invClipMatrix.Transform(corner);
			corner.Normalize();

			m_corners[BoxCorner_NearRightBottom] = Vector3<T>(corner.x, corner.y, corner.z);

			// NearRightTop
			corner.Set(F(1.0), F(1.0), F(0.0));
			corner = invClipMatrix.Transform(corner);
			corner.Normalize();

			m_corners[BoxCorner_NearRightTop] = Vector3<T>(corner.x, corner.y, corner.z);
		}
		else
			NazaraWarning("Clip matrix is not invertible, failed to compute frustum corners");

		return *this;
	}

	/*!
	* \brief Constructs the frustum from the view matrix and the projection matrix
	* \return A reference to this frustum which is the build up of projective matrix
	*
	* \param view Matrix which represents the view
	* \param projection Matrix which represents the projection (the perspective)
	*
	* \remark A NazaraWarning is produced if the product of these matrices is not inversible and corners are unchanged
	*/

	template<typename T>
	Frustum<T>& Frustum<T>::Extract(const Matrix4<T>& view, const Matrix4<T>& projection)
	{
		return Extract(Matrix4<T>::Concatenate(view, projection));
	}

	/*!
	* \brief Gets the Vector3 for the corner
	* \return The position of the corner of the frustum according to enum BoxCorner
	*
	* \param corner Enumeration of type BoxCorner
	*
	* \remark If enumeration is not defined in BoxCorner and NAZARA_DEBUG defined, a NazaraError is thrown and a Vector3 uninitialised is returned
	*/

	template<typename T>
	const Vector3<T>& Frustum<T>::GetCorner(BoxCorner corner) const
	{
		#ifdef NAZARA_DEBUG
		if (corner > BoxCorner_Max)
		{
			NazaraError("Corner not handled (0x" + String::Number(corner, 16) + ')');

			static Vector3<T> dummy;
			return dummy;
		}
		#endif

		return m_corners[corner];
	}

	/*!
	* \brief Gets the Plane for the face
	* \return The face of the frustum according to enum FrustumPlane
	*
	* \param plane Enumeration of type FrustumPlane
	*
	* \remark If enumeration is not defined in FrustumPlane and NAZARA_DEBUG defined, a NazaraError is thrown and a Plane uninitialised is returned
	*/

	template<typename T>
	const Plane<T>& Frustum<T>::GetPlane(FrustumPlane plane) const
	{
		#ifdef NAZARA_DEBUG
		if (plane > FrustumPlane_Max)
		{
			NazaraError("Frustum plane not handled (0x" + String::Number(plane, 16) + ')');

			static Plane<T> dummy;
			return dummy;
		}
		#endif

		return m_planes[plane];
	}

	/*!
	* \brief Checks whether or not a bounding volume intersects with the frustum
	* \return IntersectionSide How the bounding volume is intersecting with the frustum
	*
	* \param volume Volume to check
	*
	* \remark If volume is infinite, IntersectionSide_Intersecting is returned
	* \remark If volume is null, IntersectionSide_Outside is returned
	* \remark If enumeration of the volume is not defined in Extend, a NazaraError is thrown and IntersectionSide_Outside is returned
	* \remark If enumeration of the intersection is not defined in IntersectionSide, a NazaraError is thrown and IntersectionSide_Outside is returned. This should not never happen for a user of the library
	*/

	template<typename T>
	IntersectionSide Frustum<T>::Intersect(const BoundingVolume<T>& volume) const
	{
		switch (volume.extend)
		{
			case Extend_Finite:
			{
				IntersectionSide side = Intersect(volume.aabb);
				switch (side)
				{
					case IntersectionSide_Inside:
						return IntersectionSide_Inside;

					case IntersectionSide_Intersecting:
						return Intersect(volume.obb);

					case IntersectionSide_Outside:
						return IntersectionSide_Outside;
				}

				NazaraError("Invalid intersection side (0x" + String::Number(side, 16) + ')');
				return IntersectionSide_Outside;
			}

			case Extend_Infinite:
				return IntersectionSide_Intersecting; // We can not contain infinity

			case Extend_Null:
				return IntersectionSide_Outside;
		}

		NazaraError("Invalid extend type (0x" + String::Number(volume.extend, 16) + ')');
		return IntersectionSide_Outside;
	}

	/*!
	* \brief Checks whether or not a box intersects with the frustum
	* \return IntersectionSide How the box is intersecting with the frustum
	*
	* \param box Box to check
	*/

	template<typename T>
	IntersectionSide Frustum<T>::Intersect(const Box<T>& box) const
	{
		// http://www.lighthouse3d.com/tutorials/view-frustum-culling/geometric-approach-testing-boxes-ii/
		IntersectionSide side = IntersectionSide_Inside;

		for (unsigned int i = 0; i <= FrustumPlane_Max; i++)
		{
			if (m_planes[i].Distance(box.GetPositiveVertex(m_planes[i].normal)) < F(0.0))
				return IntersectionSide_Outside;
			else if (m_planes[i].Distance(box.GetNegativeVertex(m_planes[i].normal)) < F(0.0))
				side = IntersectionSide_Intersecting;
		}

		return side;
	}

	/*!
	* \brief Checks whether or not an oriented box intersects with the frustum
	* \return IntersectionSide How the oriented box is intersecting with the frustum
	*
	* \param oriented box OrientedBox to check
	*/

	template<typename T>
	IntersectionSide Frustum<T>::Intersect(const OrientedBox<T>& orientedbox) const
	{
		return Intersect(&orientedbox[0], 8);
	}

	/*!
	* \brief Checks whether or not a sphere intersects with the frustum
	* \return IntersectionSide How the sphere is intersecting with the frustum
	*
	* \param sphere Sphere to check
	*/

	template<typename T>
	IntersectionSide Frustum<T>::Intersect(const Sphere<T>& sphere) const
	{
		// http://www.lighthouse3d.com/tutorials/view-frustum-culling/geometric-approach-testing-points-and-spheres/
		IntersectionSide side = IntersectionSide_Inside;

		for (unsigned int i = 0; i <= FrustumPlane_Max; i++)
		{
			T distance = m_planes[i].Distance(sphere.GetPosition());
			if (distance < -sphere.radius)
				return IntersectionSide_Outside;
			else if (distance < sphere.radius)
				side = IntersectionSide_Intersecting;
		}

		return side;
	}

	/*!
	* \brief Checks whether or not a set of Vector3 intersects with the frustum
	* \return IntersectionSide How the set of Vector3 is intersecting with the frustum
	*
	* \param points Pointer to Vector3 which represents a set of points in the space
	* \param pointCount Number of points to check
	*/

	template<typename T>
	IntersectionSide Frustum<T>::Intersect(const Vector3<T>* points, unsigned int pointCount) const
	{
		unsigned int c = 0;

		for (unsigned int i = 0; i <= FrustumPlane_Max; ++i)
		{
			unsigned int j;
			for (j = 0; j < pointCount; j++ )
			{
				if (m_planes[i].Distance(points[j]) > F(0.0))
					break;
			}

			if (j == pointCount)
				return IntersectionSide_Outside;
			else
				c++;
		}

		return (c == 6) ? IntersectionSide_Inside : IntersectionSide_Intersecting;
	}

	/*!
	* \brief Sets the components of the frustum from another type of Frustum
	* \return A reference to this frustum
	*
	* \param frustum Frustum of type U to convert its components
	*/

	template<typename T>
	template<typename U>
	Frustum<T>& Frustum<T>::Set(const Frustum<U>& frustum)
	{
		for (unsigned int i = 0; i <= BoxCorner_Max; ++i)
			m_corners[i].Set(frustum.m_corners[i]);

		for (unsigned int i = 0; i <= FrustumPlane_Max; ++i)
			m_planes[i].Set(frustum.m_planes[i]);

		return *this;
	}

	/*!
	* \brief Gives a string representation
	* \return A string representation of the object: "Frustum(Plane ...)"
	*/

	template<typename T>
	String Frustum<T>::ToString() const
	{
		StringStream ss;

		return ss << "Frustum(Bottom: " << m_planes[FrustumPlane_Bottom].ToString() << "\n"
		       << "        Far: " << m_planes[FrustumPlane_Far].ToString() << "\n"
		       << "        Left: " << m_planes[FrustumPlane_Left].ToString() << "\n"
		       << "        Near: " << m_planes[FrustumPlane_Near].ToString() << "\n"
		       << "        Right: " << m_planes[FrustumPlane_Right].ToString() << "\n"
		       << "        Top: " << m_planes[FrustumPlane_Top].ToString() << ")\n";
	}

	/*!
	* \brief Serializes a Frustum
	* \return true if successfully serialized
	*
	* \param context Serialization context
	* \param matrix Input frustum
	*/
	template<typename T>
	bool Serialize(SerializationContext& context, const Frustum<T>& frustum, TypeTag<Frustum<T>>)
	{
		for (unsigned int i = 0; i <= BoxCorner_Max; ++i)
		{
			if (!Serialize(context, frustum.m_corners[i]))
				return false;
		}

		for (unsigned int i = 0; i <= FrustumPlane_Max; ++i)
		{
			if (!Serialize(context, frustum.m_planes[i]))
				return false;
		}

		return true;
	}

	/*!
	* \brief Unserializes a Frustum
	* \return true if successfully unserialized
	*
	* \param context Serialization context
	* \param matrix Output frustum
	*/
	template<typename T>
	bool Unserialize(SerializationContext& context, Frustum<T>* frustum, TypeTag<Frustum<T>>)
	{
		for (unsigned int i = 0; i <= BoxCorner_Max; ++i)
		{
			if (!Unserialize(context, &frustum->m_corners[i]))
				return false;
		}

		for (unsigned int i = 0; i <= FrustumPlane_Max; ++i)
		{
			if (!Unserialize(context, &frustum->m_planes[i]))
				return false;
		}

		return true;
	}
}

/*!
* \brief Output operator
* \return The stream
*
* \param out The stream
* \param frustum The frustum to output
*/

template<typename T>
std::ostream& operator<<(std::ostream& out, const Nz::Frustum<T>& frustum)
{
	return out << frustum.ToString();
}

#undef F

#include <Nazara/Core/DebugOff.hpp>