#ifndef __MUTUAL_VISIBILITY_H
#define __MUTUAL_VISIBILITY_H

#include "Vector3.h"
#include "Ray.h"

namespace GtpVisibilityPreprocessor {

class Intersectable;
class AxisAlignedBox3;
class SceneGraph;


struct RaySample {
  /// true if the sample really intersects both boxes
  float mMinT;
  float mMaxT;

  RaySample():mMinT(-1.0f), mMaxT(-1.0f) {}
  /// intersections of the sample with the scene
  vector<Ray::Intersection> mIntersections;
  void SetInvalid() {
    mMinT = 0.0f;
    mMaxT = -1.0f;
  }
  bool IsValid() const { return mMaxT > 0.0f; }
  bool IsProcessed() const { return mMinT != mMaxT; }
};

struct RayShaft {
public:
  /// evaluted sampling error
  float mError;
  /// depth in recursion
  int mDepth;
  /// The source triangle
  Rectangle3 mSource;
  /// The target triangle
  Rectangle3 mTarget;
  
  RaySample mSamples[4];
  
  void ComputeError();
  
  RayShaft() {}
  
  RayShaft (
	    const Rectangle3 &source,
	    const Rectangle3 &target)
  {
    Init(source, target);
  }

  bool IsValid() const { return
			   mSamples[0].IsValid() &&
			   mSamples[1].IsValid() &&
			   mSamples[2].IsValid() &&
			   mSamples[3].IsValid();
  }

  // initial triangle sample
  void Init(
	    const Rectangle3 &source,
	    const Rectangle3 &target);
  
  Vector3
  GetIntersectionPoint(const int rayIndex,
		       const int depth) const;
  
  void GetRay(const int rayIndex,
	      Vector3 &origin,
	      Vector3 &direction) const;

  void
  GetRaySegment(const int i, Ray &ray) const;

};

enum { VISIBLE, INVISIBLE };

  
class MutualVisibilitySampler {
public:
  SceneGraph *mSceneGraph;
  KdTree *mKdTree;
  AxisAlignedBox3 mSource;
  AxisAlignedBox3 mTarget;
  float mSolidAngleThreshold;
  bool mUseBoxes;

  MutualVisibilitySampler(
						  SceneGraph *sceneGraph,
						  KdTree *kdTree,
						  const AxisAlignedBox3 &source,
						  const AxisAlignedBox3 &target,
						  const float solidAngleThreshold
						  );
  int
  ComputeVisibility();

  void
  ConstructInitialSamples(const AxisAlignedBox3 &source,
						  const AxisAlignedBox3 &target,
						  vector<RayShaft *> &samples
						  );
	
  void
  ConstructInitialSamples2(
						   const AxisAlignedBox3 &source,
						   const AxisAlignedBox3 &target,
						   vector<RayShaft *> &samples
						   );
	
  void
  ConstructInitialSamples3(
						   const AxisAlignedBox3 &source,
						   const AxisAlignedBox3 &target,
						   vector<RayShaft *> &samples
						   );
	
  void
  AddInitialSamples(
					const Rectangle3 &sourceRect,
					const Rectangle3 &targetRect,
					vector<RayShaft *> &samples
					);
	
  void
  AddInitialSamples2(
					 const Rectangle3 &sourceRect,
					 const Rectangle3 &targetRect,
					 vector<RayShaft *> &samples
					 );
	
  // the split sample method contains a methodology to create new samples
  // or terminate the sampling
  bool
  SplitSample(
			const RayShaft &source,
			RayShaft &sample1,
			RayShaft &sample2
			);
  void
  PerformSplit(
				const RayShaft &sample,
				const bool splitSource,
				const int axis,
				RayShaft &sample1,
				RayShaft &sample2
				 );
  
	
  bool
  SampleTerminationCriteriaMet(
								 const RayShaft &sample);
  
  float
  GetSpatialAngle(const RayShaft &sample,
				  const Vector3 &point
				 );
	
  int
  CastRays(RayShaft &shaft);
	
  void
  ComputeError(RayShaft &sample);
  
  void
  ExportShafts(vector<RayShaft *> &samples, const bool singleFile);


};
  
int
ComputeBoxVisibility(SceneGraph *sceneGraph,
		     KdTree *kdTree,
		     const AxisAlignedBox3 &source,
		     const AxisAlignedBox3 &target,
		     const float solidAngleThreshold);




}

#endif