#ifndef _Plane3_H__
#define _Plane3_H__

#include "Vector3.h"

namespace GtpVisibilityPreprocessor {

struct SimpleRay;

/** 3D Plane.
*/
class Plane3 {
public:

  Vector3 mNormal;
  float mD;
  
  Plane3() {}
  
  Plane3(const Vector3 &a,
		 const Vector3 &b,
		 const Vector3 &c
		 );

  Plane3(const Vector3 &normal,
		 const Vector3 &point
		 );

  void ReverseOrientation()
  {
	  mNormal *= -1;
	  mD *= -1;
  }

  float Distance(const Vector3 &v) const 
  {
	  return DotProd(v, mNormal) + mD;
  }

  enum {BACK_SIDE = -1, INTERSECTS = 0, FRONT_SIDE = 1};
		 
		
  /** Returns 1 if v is on front side, -1 if on back side, 0 if on plane.
  */
  int Side(const Vector3 &v, const float threshold = 1e-6) const;

  /** Finds intersection of line segment between points a and b with plane.
	  @param a start point
	  @param b end point
	  @param t if not NULL, returns parameter value of intersections
	  @param coplanar if not NULL, returns true if plane and line segments are coplanar.
  */
  Vector3 FindIntersection(const Vector3 &a,
						   const Vector3 &b,
						   float *t = NULL,
						   bool *coplanar = NULL) const;
  
  /** Finds value of intersection parameter t on line segment from a to b.
      @returns 0 if coplanar, else parameter t
  */
  float FindT(const Vector3 &a, const Vector3 &b) const;

  float FindT(const SimpleRay &a) const;

  friend bool
  PlaneIntersection(const Plane3 &a, const Plane3 &b, const Plane3 &c, Vector3 &result);
  
  friend bool PlaneIntersection(const Plane3 &p1, const Plane3 &p2);

  friend SimpleRay GetPlaneIntersection(const Plane3 &plane1, const Plane3 &plane2);

  friend ostream &operator<<(ostream &s, const Plane3 &p) {
    s<<p.mNormal<<" "<<p.mD;
    return s;
  }

  
};
  

/** A definition for an axis aligned plane.
*/
struct AxisAlignedPlane
{
public:
	AxisAlignedPlane(){}
	AxisAlignedPlane(const int axis, const float position):
	  mAxis(axis), mPosition(position), mOrientation(false)
	  {
	  }
	Plane3 GetPlane() const
	{
		Vector3 normal(0,0,0); normal[mAxis] = mOrientation ? 1.0f : -1.0f;
		Vector3 point(0,0,0); point[mAxis] = mPosition;

        return Plane3(normal, point);
	}

	/// the split axis: one of 0=x, 1=y, 2=z
	int mAxis;
	/// the absolute position of the split axis
	float mPosition;
	/// the plane orientation
	bool mOrientation;

	friend ostream &operator<<(ostream &s, const AxisAlignedPlane &p) 
	{
		s << "a: " << p.mAxis << " p: " << p.mPosition;
		return s;
	}
};
}
#endif