175 lines
6.8 KiB
Plaintext
Executable File
175 lines
6.8 KiB
Plaintext
Executable File
// ======================================================================== //
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// Copyright 2009-2013 Intel Corporation //
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// //
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// Licensed under the Apache License, Version 2.0 (the "License"); //
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// you may not use this file except in compliance with the License. //
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// You may obtain a copy of the License at //
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// //
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// http://www.apache.org/licenses/LICENSE-2.0 //
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// //
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// Unless required by applicable law or agreed to in writing, software //
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// distributed under the License is distributed on an "AS IS" BASIS, //
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. //
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// See the License for the specific language governing permissions and //
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// limitations under the License. //
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// ======================================================================== //
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#pragma once
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/*! \addtogroup rivl_render_embree_ivl */
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/*! @{ */
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/*! Reflects a viewing vector V at a normal N. */
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inline Sample3f reflect_(const Vec3f &V, const Vec3f &N) {
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float cosi = dot(V,N);
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return make_Sample3f(2.0f*cosi*N-V, 1.0f);
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}
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/*! Reflects a viewing vector V at a normal N. Cosine between V
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* and N is given as input. */
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inline Sample3f reflect_(const Vec3f &V, const Vec3f &N, const float cosi) {
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return make_Sample3f(2.0f*cosi*N-V, 1.0f);
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}
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// =======================================================
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/*!Refracts a viewing vector V at a normal N using the relative
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* refraction index eta. Eta is refraction index of outside medium
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* (where N points into) divided by refraction index of the inside
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* medium. The vectors V and N have to point towards the same side
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* of the surface. The cosine between V and N is given as input and
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* the cosine of -N and transmission ray is computed as output. */
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inline Sample3f refract(const Vec3f& V, const Vec3f& N, const float eta,
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const float cosi, float &cost)
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{
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const float k = 1.0f-eta*eta*(1.0f-cosi*cosi);
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if (k < 0.0f) { cost = 0.0f; return make_Sample3f(make_Vec3f(0.f),0.0f); }
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cost = sqrt(k);
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return make_Sample3f(eta*(cosi*N-V)-cost*N, sqr(eta));
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}
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/*! Computes fresnel coefficient for media interface with relative
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* refraction index eta. Eta is the outside refraction index
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* divided by the inside refraction index. Both cosines have to be
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* positive. */
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inline float fresnelDielectric(const float cosi, const float cost, const float eta)
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{
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const float Rper = (eta*cosi - cost) * rcp(eta*cosi + cost);
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const float Rpar = ( cosi - eta*cost) * rcp( cosi + eta*cost);
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return 0.5f*(Rpar*Rpar + Rper*Rper);
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}
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/*! Computes fresnel coefficient for media interface with relative
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* refraction index eta. Eta is the outside refraction index
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* divided by the inside refraction index. The cosine has to be
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* positive. */
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inline float fresnelDielectric(const float cosi, const float eta)
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{
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const float k = 1.0f-eta*eta*(1.0f-cosi*cosi);
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if (k < 0.0f) return 1.0f;
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const float cost = sqrt(k);
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return fresnelDielectric(cosi, cost, eta);
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}
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/*! Computes fresnel coefficient for conductor medium with complex
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* refraction index (eta,k). The cosine has to be positive. */
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inline Vec3f fresnelConductor(const float cosi, const Vec3f& eta, const Vec3f& k)
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{
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const Vec3f tmp = eta*eta + k*k;
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const Vec3f Rpar = (tmp * (cosi*cosi) - 2.0f*eta*cosi + make_Vec3f(1.0f)) *
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rcp(tmp * (cosi*cosi) + 2.0f*eta*cosi + make_Vec3f(1.0f));
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const Vec3f Rper = (tmp - 2.0f*eta*cosi + make_Vec3f(cosi*cosi)) *
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rcp(tmp + 2.0f*eta*cosi + make_Vec3f(cosi*cosi));
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return 0.5f * (Rpar + Rper);
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}
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// =======================================================
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struct FresnelConductor {
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Vec3f eta; //!< Real part of refraction index
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Vec3f k; //!< Imaginary part of refraction index
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};
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inline Vec3f eval(varying const FresnelConductor& THIS, const float cosTheta) {
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return fresnelConductor(cosTheta,THIS.eta,THIS.k);
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}
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inline uniform FresnelConductor make_FresnelConductor(const uniform Vec3f& eta, const uniform Vec3f& k) {
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uniform FresnelConductor m; m.eta = eta; m.k = k; return m;
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}
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#if defined(ISPC)
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inline varying FresnelConductor make_FresnelConductor(const varying Vec3f& eta, const varying Vec3f& k) {
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varying FresnelConductor m; m.eta = eta; m.k = k; return m;
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}
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#endif
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// =======================================================
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struct FresnelDielectric
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{
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/*! refraction index of the medium the incident ray travels in */
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float etai;
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/*! refraction index of the medium the outgoing transmission rays
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* travels in */
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float etat;
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};
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inline Vec3f eval(const uniform FresnelDielectric& THIS, const float cosTheta) {
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return make_Vec3f(fresnelDielectric(cosTheta,THIS.etai/THIS.etat));
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}
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inline uniform FresnelDielectric make_FresnelDielectric(const uniform float etai, const uniform float etat) {
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uniform FresnelDielectric m; m.etai = etai; m.etat = etat; return m;
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}
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#if defined(ISPC)
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inline varying FresnelDielectric make_FresnelDielectric(const varying float etai, const varying float etat) {
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varying FresnelDielectric m; m.etai = etai; m.etat = etat; return m;
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}
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#endif
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// =======================================================
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struct PowerCosineDistribution {
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float exp;
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};
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inline float eval(const uniform PowerCosineDistribution &THIS, const float cosThetaH) {
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return (THIS.exp+2) * (1.0f/(2.0f*(M_PI))) * pow(abs(cosThetaH), THIS.exp);
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}
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#if defined(ISPC)
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inline float eval(const varying PowerCosineDistribution &THIS, const float cosThetaH) {
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return (THIS.exp+2) * (1.0f/(2.0f*(M_PI))) * pow(abs(cosThetaH), THIS.exp);
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}
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#endif
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/*! Samples the power cosine distribution. */
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inline void sample(const uniform PowerCosineDistribution& THIS, const Vec3f& wo, const Vec3f& N, Sample3f &wi, const Vec2f s)
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{
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Sample3f wh = powerCosineSampleHemisphere(s.x,s.y,N,THIS.exp);
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Sample3f r = reflect_(wo,wh.v);
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wi = make_Sample3f(r.v,wh.pdf/(4.0f*abs(dot(wo,wh.v))));
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}
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/*! Samples the power cosine distribution. */
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#if defined(ISPC)
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inline void sample(const varying PowerCosineDistribution& THIS, const Vec3f& wo, const Vec3f& N, Sample3f &wi, const Vec2f s)
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{
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Sample3f wh = powerCosineSampleHemisphere(s.x,s.y,N,THIS.exp);
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Sample3f r = reflect_(wo,wh.v);
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wi = make_Sample3f(r.v,wh.pdf/(4.0f*abs(dot(wo,wh.v))));
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}
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#endif
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inline uniform PowerCosineDistribution make_PowerCosineDistribution(const uniform float _exp) {
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uniform PowerCosineDistribution m; m.exp = _exp; return m;
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}
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#if defined(ISPC)
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inline varying PowerCosineDistribution make_PowerCosineDistribution(const varying float _exp) {
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varying PowerCosineDistribution m; m.exp = _exp; return m;
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}
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#endif
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/*! @} */
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