Lambert.cpp

#include "Lambert.h"
#include "Ray.h"
#include "Scene.h"
#include <algorithm>

Lambert::Lambert(const Vector3 & kd) :
	m_kd(kd)
{
}

Lambert::~Lambert()
{
}

Vector3
Lambert::shade(const Ray& ray, const HitInfo& hit, const Scene& scene) const
{
	Vector3 L = Vector3(0.0f, 0.0f, 0.0f);

	const Vector3 viewDir = -ray.d; // d is a unit vector

	const Lights *lightlist = scene.lights();

	// loop over all of the lights
	Lights::const_iterator lightIter;
	for (lightIter = lightlist->begin(); lightIter != lightlist->end(); lightIter++)
	{
		PointLight* pLight = *lightIter;

		Vector3 l = pLight->position() - hit.P;

		// the inverse-squared falloff
		float falloff = l.length2();

		// normalize the light direction
		l /= sqrt(falloff);

		// get the irradiance
		Vector3 irradiance = (pLight->color() * pLight->wattage()) * std::max(0.0f, dot(hit.N, l)) / (4.0 * PI * falloff);

		L += irradiance * (m_kd / PI);
	}

	return L;
}