#ifndef TRIANGLE_H
#define TRIANGLE_H

#include "entity.h"
#include "lin_alg.h"

class Triangle : public Entity
{
public:
	Triangle(const vector3d& x, const vector3d& y, const vector3d& z)
	{
		a = x;
		b = y;
		c = z;
		UpdateNorm();
	}
	virtual ~Triangle() {}
	virtual RayIntersect CalcRayIntersect(Ray ray);
	virtual vector3d CalcNormal(Ray ray, RayIntersect&ri);
	virtual void PathCompress(const Transform&T,
							  queue<pair<Entity*,Transform> >&,
							  vector<Entity*>&);
	virtual int IntersectionTest(Ray ray);

	const vector3d& GetA() {return a;}
	const vector3d& GetB() {return b;}
	const vector3d& GetC() {return c;}

private:
	void UpdateNorm()
	{
		norm = (b-a).cross(c-a);
		norm.make_unit();
	}
	vector3d a, b, c, norm;
};

double intersect_triangle_ray(Ray & ray, vector3d&a, vector3d&b, vector3d&c,
							  double&aa, double&bb);

inline void Triangle::PathCompress(const Transform&T,
								   queue<pair<Entity*,Transform> >&Q,
								   vector<Entity*>&V)
{
	Triangle * tr = new Triangle(*this);
 	tr->a = T*a;
 	tr->b = T*b;
 	tr->c = T*c;
	tr->UpdateNorm();
	V.push_back(tr);
}

inline RayIntersect Triangle::CalcRayIntersect(Ray ray)
{
	RayIntersect ri;
	double aa, bb;
	ri.param_t = intersect_triangle_ray(ray, a, b, c, aa, bb);
	ri.E = ri.param_t < 1 ? 0 : this;
	return ri;
}

inline int Triangle::IntersectionTest(Ray ray)
{
	double aa, bb;
	return intersect_triangle_ray(ray, a, b, c, aa, bb) > 0;
}

inline vector3d Triangle::CalcNormal(Ray ray, RayIntersect&ri)
{
	return norm;
}

#endif