#ifndef __TRIANGLE3_H
#define __TRIANGLE3_H

#include "Vector3.h"


namespace GtpVisibilityPreprocessor {

class AxisAlignedBox3;
class Ray;
class Plane3;

struct Triangle3 
{
	Triangle3() {};
	Triangle3(const Vector3 &a, const Vector3 &b, const Vector3 &c);

	void Init(const Vector3 &a, const Vector3 &b, const Vector3 &c);

	Vector3 GetNormal() const;

	Vector3 GetCenter() const;

	float GetSpatialAngle(const Vector3 &point) const;

	float GetArea() const;

	/// returns bounding box around this triangle
	AxisAlignedBox3 GetBoundingBox() const;

	/// Casts ray into this triangle. Returns hit
	int CastRay(const Ray &ray, float &t, const float nearestT, Vector3 &normal) const;

	friend ostream& operator<< (ostream &s, const Triangle3 &A);
	friend istream& operator>> (istream &s, Triangle3 &A);

	/** Checks if this triangle is ill-defined.
	*/
	bool CheckValidity() const;

	/** Intersects triangle with plane, returns intersection points
		if intersection is happening.

		@returns true if triangle intersects plane
	*/
	bool GetPlaneIntersection(const Plane3 &plane, 
							  Vector3 &intersectA, 
							  Vector3 &intersectB) const;

	///////////////////

	/// the triangle vertices
	Vector3 mVertices[3];
};


// Overload << operator for C++-style output
inline ostream&
operator<< (ostream &s, const Triangle3 &A)
{
  return s << "(" << A.mVertices[0] << ", " << A.mVertices[1] << ", " << A.mVertices[2] << ")";
}

// Overload >> operator for C++-style input
inline istream&
operator>> (istream &s, Triangle3 &A)
{
  char a;
  // read "(x, y, z)"
  return s >> a >> A.mVertices[0] >> a >> A.mVertices[1] >> a >> A.mVertices[2] >> a;
}


}

#endif