sampling.hpp

#pragma once

//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------
#pragma region

#include "vector.hpp"

#pragma endregion

//-----------------------------------------------------------------------------
// Declarations and Definitions
//-----------------------------------------------------------------------------
namespace pathtracing
{

inline const Vector3 UniformSampleOnSphere(
	double u1, double u2) noexcept
{

	const double cos_theta = 1.0 - 2.0 * u1;
	const double sin_theta = sqrt(std::max(0.0, 1.0 - cos_theta * cos_theta));
	const double phi = 2.0 * g_pi * u2;
	return Vector3(cos(phi) * sin_theta, sin(phi) * sin_theta, cos_theta);
}

inline const Vector3 UniformSampleOnHemisphere(
	double u1, double u2) noexcept
{

	// u1 := cos_theta
	const double sin_theta = sqrt(std::max(0.0, 1.0 - u1 * u1));
	const double phi = 2.0 * g_pi * u2;
	return Vector3(cos(phi) * sin_theta, sin(phi) * sin_theta, u1);
}

inline const Vector3 CosineWeightedSampleOnHemisphere(
	double u1, double u2) noexcept
{

	const double cos_theta = sqrt(1.0 - u1);
	const double sin_theta = sqrt(u1);
	const double phi = 2.0 * g_pi * u2;
	return Vector3(cos(phi) * sin_theta, sin(phi) * sin_theta, cos_theta);
}
} // namespace pathtracing