104 lines
3.4 KiB
C++
104 lines
3.4 KiB
C++
/*
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This file is part of Nori, a simple educational ray tracer
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Copyright (c) 2015 by Wenzel Jakob
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Nori is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License Version 3
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as published by the Free Software Foundation.
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Nori is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <nori/bsdf.h>
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#include <nori/frame.h>
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#include <nori/warp.h>
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NORI_NAMESPACE_BEGIN
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class Microfacet : public BSDF {
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public:
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Microfacet(const PropertyList &propList) {
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/* RMS surface roughness */
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m_alpha = propList.getFloat("alpha", 0.1f);
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/* Interior IOR (default: BK7 borosilicate optical glass) */
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m_intIOR = propList.getFloat("intIOR", 1.5046f);
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/* Exterior IOR (default: air) */
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m_extIOR = propList.getFloat("extIOR", 1.000277f);
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/* Albedo of the diffuse base material (a.k.a "kd") */
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m_kd = propList.getColor("kd", Color3f(0.5f));
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/* To ensure energy conservation, we must scale the
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specular component by 1-kd.
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While that is not a particularly realistic model of what
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happens in reality, this will greatly simplify the
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implementation. Please see the course staff if you're
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interested in implementing a more realistic version
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of this BRDF. */
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m_ks = 1 - m_kd.maxCoeff();
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}
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/// Evaluate the BRDF for the given pair of directions
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Color3f eval(const BSDFQueryRecord &bRec) const {
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throw NoriException("MicrofacetBRDF::eval(): not implemented!");
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}
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/// Evaluate the sampling density of \ref sample() wrt. solid angles
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float pdf(const BSDFQueryRecord &bRec) const {
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throw NoriException("MicrofacetBRDF::pdf(): not implemented!");
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}
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/// Sample the BRDF
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Color3f sample(BSDFQueryRecord &bRec, const Point2f &_sample) const {
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throw NoriException("MicrofacetBRDF::sample(): not implemented!");
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// Note: Once you have implemented the part that computes the scattered
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// direction, the last part of this function should simply return the
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// BRDF value divided by the solid angle density and multiplied by the
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// cosine factor from the reflection equation, i.e.
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// return eval(bRec) * Frame::cosTheta(bRec.wo) / pdf(bRec);
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}
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bool isDiffuse() const {
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/* While microfacet BRDFs are not perfectly diffuse, they can be
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handled by sampling techniques for diffuse/non-specular materials,
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hence we return true here */
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return true;
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}
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std::string toString() const {
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return tfm::format(
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"Microfacet[\n"
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" alpha = %f,\n"
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" intIOR = %f,\n"
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" extIOR = %f,\n"
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" kd = %s,\n"
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" ks = %f\n"
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"]",
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m_alpha,
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m_intIOR,
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m_extIOR,
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m_kd.toString(),
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m_ks
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);
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}
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private:
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float m_alpha;
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float m_intIOR, m_extIOR;
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float m_ks;
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Color3f m_kd;
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};
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NORI_REGISTER_CLASS(Microfacet, "microfacet");
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NORI_NAMESPACE_END
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