// This file may be redistributed and modified only under the terms of
// the GNU General Public License (See COPYING for details).
// Copyright (C) 2005 Alistair Riddoch

#ifndef MERCATOR_AREA_H
#define MERCATOR_AREA_H

#include "Effector.h"

#include <wfmath/axisbox.h>
#include <wfmath/polygon.h>

namespace Mercator {

class Segment;

class Shader;

/// \brief Region of terrain surface which is modified.
///
/// Objects of this class describe regions of the surface which have
/// been changed. Which layers of the shaded terrain is affected by
/// their layer number. For example, if they are below the snow layer
/// then the snow shader will cover them where the area affected by
/// snow intersects with the area, but the lower grass area will be
/// overriden. In order to get the best effect it is important to
/// select the layer carefully.
class Area : public Effector {
public:
	/// \brief Constructor
	///
	/// @param layer layer number.
	/// @param hole flag indicating whether this is a hole.
	Area(int layer, bool hole);

	/// Set the geometric shape of this area.
	void setShape(const WFMath::Polygon<2>& p);

	/// Determine if a point is contained by the shape of this area.
	bool contains(WFMath::CoordType x, WFMath::CoordType z) const;

	/// Accessor for the layer number.
	int getLayer() const {
		return m_layer;
	}

	/// Accessor for the flag indicating whether this is a hole.
	bool isHole() const {
		return m_hole;
	}

	/// Accessor for the geometric shape.
	const WFMath::Polygon<2>& shape() const {
		return m_shape;
	}

	/**
	Test if a segment intersects this area
	*/
	bool checkIntersects(const Segment& s) const override;

	/// \brief Clip the shape of this area to a given segment.
	///
	/// Determines the intersection of the geometric shape of this area
	/// with a square terrain segment, and returns the intersection as
	/// a geometric shape.
	/// @param s the segment that the shape should be clipped to.
	/// @returns the shape of the intersection of this area with the segment.
	WFMath::Polygon<2> clipToSegment(const Segment& s) const;

private:

	/// The layer number.
	int m_layer;
	/// A flag indicating whether this is a hole.
	bool m_hole;
	/// The geometric shape.
	WFMath::Polygon<2> m_shape;
};

}

#endif // of MERCATOR_AREA_H
