#ifndef _WHITTED_INTEGRATOR_H_
#define _WHITTED_INTEGRATOR_H_

#include "Integrator.h"
#include "Scene.h"

class WhittedIntegrator : public Integrator
{
public:
	float3 /*getColor*/ Li(Ray *ray, const Scene *scene, Sample *sample, int depth = 0)
	{
		float3 color = 0.0f;
		
		if(depth > 6) {return color;}
		
		if(!scene->accelerator->Trace(*ray)) {return 0.0f;}
		Intersection i;
		ray->object->GetIntersection(*ray, i);
		
		// ambient
		color += i.material->ka;
		// direct lighting
		LightList::const_iterator light;
		for(light = scene->lights.begin(); light != scene->lights.end(); light++)
		{
			color += (*light)->computeDirectContribution(i, scene, sample);
		}
		// reflection
		if(i.material->kr > 0.0f)
		{
			Ray refl(i.p + i.n * 1e-3f, Ray::reflect(-ray->direction, i.n));
			color += /*getColor*/ Li(&refl, scene, sample, depth + 1) * i.material->kr;
		}
		// transmission
		if(i.material->kt > 0.0f)
		{
			float3 sourceIOR = float3(1.f);
			float3 targetIOR = i.material->nt;
			if(dot(i.n, ray->direction) > 0)
			{
				sourceIOR = i.material->nt;
				targetIOR = float3(1.f);
			}
			for(int c = 0; c < 3; c++)
			{
				Ray refr(i.p, Ray::refract(-ray->direction, i.n, sourceIOR[c], targetIOR[c]));
				refr.origin += 1e-3f * refr.direction;
				float3 filter(0.f);
				filter[c] = 1.f;
				color += /*getColor*/Li(&refr, scene, sample, depth + 1) * filter * i.material->kt;
			}
		}
		/* absorption from the material between ray.origin and i.p */
		color *= ray->absorb(i);
		
		return color;
	}
};

#endif