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// Copyright 2009 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#pragma once
#include "math/sampling.ih"
#include "rkcommon/math/LinearSpace.ih"
OSPRAY_BEGIN_ISPC_NAMESPACE
/*! Reflects a viewing vector I at a normal N. Cosine between I
* and N is given as input. */
inline vec3f reflect(const vec3f &I, const vec3f &N, float cosI)
{
return (2.0f * cosI) * N - I;
}
/*! Reflects a viewing vector I at a normal N. */
inline vec3f reflect(const vec3f &I, const vec3f &N)
{
return reflect(I, N, dot(I, N));
}
// helper function which computes cosT^2 from cosI and eta
inline float sqrCosT(const float cosI, const float eta)
{
return 1.0f - sqr(eta) * (1.0f - sqr(cosI));
}
//! \brief Refracts a viewing vector I at a normal N
/*! \detailed Refracts a viewing vector I at a normal N using the
* relative refraction index eta. Eta is refraction index of outside
* medium (where N points into) divided by refraction index of the
* inside medium. The vectors I and N have to point towards the same
* side of the surface. The cosine between I and N, and the cosine of -N and
* the refracted ray is given as input */
inline vec3f refract(
const vec3f &I, const vec3f &N, float cosI, float cosT, float eta)
{
return eta * (cosI * N - I) - cosT * N;
}
inline vec3f refract(const vec3f &I, const vec3f &N, float cosI, float eta)
{
const float sqrcost = sqrCosT(cosI, eta);
if (sqrcost < 0.0f)
return make_vec3f(0.f);
return refract(I, N, cosI, sqrt(sqrcost), eta);
}
inline float refract(float cosI, float eta)
{
const float sqrcost = sqrCosT(cosI, eta);
return sqrt(max(sqrcost, 0.0f));
}
OSPRAY_END_ISPC_NAMESPACE
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