mingzailao
/
mitsuba
mirror of https://github.com/Quartenia/mitsuba.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity
mitsuba/src/bsdfs/conductor.cpp

269 lines
11 KiB
C++
Raw Blame History

/*
This file is part of Mitsuba, a physically based rendering system.
Copyright (c) 2007-2011 by Wenzel Jakob and others.
Mitsuba is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License Version 3
as published by the Free Software Foundation.
Mitsuba is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <mitsuba/render/bsdf.h>
#include <mitsuba/render/texture.h>
#include <mitsuba/core/fresolver.h>
MTS_NAMESPACE_BEGIN
/*! \plugin{conductor}{Smooth conductor}
* \parameters{
* \parameter{preset}{\String}{Name of a material preset, see
* \tblref{conductor-iors}.\!\default{\texttt{Cu} / copper}}
* \parameter{eta}{\Spectrum}{Real part of the material's index of refraction
* \default{based on the value of \texttt{preset}}}
* \parameter{k}{\Spectrum}{Imaginary part of the material's index of
* refraction, also known as absorption coefficient.
* \default{based on the value of \texttt{preset}}}
* \lastparameter{specular\showbreak Reflectance}{\Spectrum\Or\Texture}{Optional
* factor used to modulate the reflectance component\default{1.0}}
* }
* \renderings{
* \rendering{Measured copper material (the default)}{bsdf_conductor_copper.jpg}
* \rendering{Measured gold material (\lstref{conductor-gold})}{bsdf_conductor_gold.jpg}
* }
* This plugin implements a perfectly smooth interface to a conducting material,
* such as a metal. For a similar model that instead describes a rough surface
* microstructure, take a look at the seperately available
* \pluginref{roughconductor} plugin.
* In contrast to dielectric materials, conductors do not transmit
* any light. Their index of refraction is complex-valued and tends to undergo
* considerable changes throughout the visible color spectrum.
*
* To faciliate the tedious task of specifying spectrally-varying index of
* refraction information, Mitsuba ships with a set of measured data for a
* several materials, where visible-spectrum information was publicly available\footnote{
* These index of refraction values are identical to the data distributed with PBRT.
* They are originally from the Luxpop database (\url{www.luxpop.com}) and
* are based on data by Palik et al. \cite{Palik1998Handbook} and measurements
* of atomic scattering factors made by the Center For X-Ray Optics (CXRO)
* at Berkeley and the Lawrence Livermore National Laboratory (LLNL).
* }.
*
* Note that \tblref{conductor-iors} also includes several popular optical coatings, which are
* not actually conductors. These materials can also be used with this plugin,
* though note that the plugin will ignore any refraction component that the actual
* material might have had.
* The table also contains a few birefingent materials, which are split into
* separate measurements correponding to their two indices of
* refraction (named ``ordinary'' and ``extraordinary ray'').
*
* When using this plugin, you should compile Mitsuba with support for spectral
* renderings to get the most accurate results. While it also works in RGB mode,
* the computations will be much more approximate in this case.
*
* \begin{xml}[caption=Material configuration for a smooth conductor with measured gold data, label=lst:conductor-gold]
* <shape type="...">
* <bsdf type="conductor">
* <string name="preset" value="Au"/>
* </bsdf>
* <shape>
* \end{xml}
* \vspace{5mm}
* It is also possible to load spectrally varying index of refraction data from
* two external files (see \secref{format-spectra} for details on the file format):
* \begin{xml}[caption=Rendering a smooth conductor with custom data]
* <shape type="...">
* <bsdf type="conductor">
* <spectrum name="eta" filename="conductorIOR.eta.spd"/>
* <spectrum name="k" filename="conductorIOR.k.spd"/>
* </bsdf>
* <shape>
* \end{xml}
* \vspace{1.5cm}
* \begin{table}[hb!]
* \centering
* \scriptsize
* \begin{tabular}{>{\ttfamily}llp{1mm}>{\ttfamily}ll}
* \toprule
* \rmfamily\textbf{Preset(s)} & \textbf{Description} &&
* \rmfamily\textbf{Preset(s)} & \textbf{Description}\\
* \cmidrule{1-2} \cmidrule{4-5}
* a-C & Amorphous carbon && Na\_palik & Sodium \\
* Ag & Silver && Nb, Nb\_palik & Niobium \\
* Al & Aluminium && Ni\_palik & Nickel \\
* AlAs, AlAs\_palik & Cubic aluminium arsenide && Rh, Rh\_palik & Rhodium \\
* AlSb, AlSb\_palik & Cubic aluminium antimonide && Se, Se\_palik & Selenium (ord. ray) \\
* Au & Gold && Se-e, Se-e\_palik & Selenium (extr. ray) \\
* Be, Be\_palik & Polycrystalline beryllium && SiC, SiC\_palik & Hexagonal silicon carbide \\
* Cr & Chromium && SnTe, SnTe\_palik & Tin telluride\\
* CsI, CsI\_palik & Cubic caesium iodide && Ta, Ta\_palik & Tantalum \\
* Cu, Cu\_palik & Copper && Te, Te\_palik & Trigonal tellurium (ord. ray) \\
* Cu2O, Cu2O\_palik & Copper (I) oxide && Te-e, Te-e\_palik & Trigonal tellurium (extr. ray) \\
* CuO, CuO\_palik & Copper (II) oxide && ThF4, ThF4\_palik & Polycryst. thorium (IV) fluoride \\
* d-C, d-C\_palik & Cubic diamond && TiC, TiC\_palik & Polycrystalline titanium carbide \\
* Hg, Hg\_palik & Mercury && TiN, TiN\_palik & Titanium nitride \\
* HgTe, HgTe\_palik & Mercury telluride && TiO2, TiO2\_palik & Tetragonal titan. dioxide (ord. ray) \\
* Ir, Ir\_palik & Iridium && TiO2-e, TiO2-e\_palik & Tetragonal titan. dioxide (extr. ray) \\
* K, K\_palik & Polycrystalline potassium && VC, VC\_palik & Vanadium carbide \\
* Li, Li\_palik & Lithium && V\_palik & Vanadium \\
* MgO, MgO\_palik & Magnesium oxide && VN, VN\_palik & Vanadium nitride \\
* Mo, Mo\_palik & Molybdenum && W & Tungsten\\
* \bottomrule
* \end{tabular}
* \caption{
* \label{tbl:conductor-iors}
* This table lists all supported material names that can be passed into the
* \pluginref{conductor} plugin. Note that some of them are not actually
* conductors---this is not a problem, they can be used regardless (though only
* the reflection component and no transmission will be simulated).
* In most cases, there are multiple entries for each material, which
* represent different measurements.
* }
* \end{table}
*/
class SmoothConductor : public BSDF {
public:
SmoothConductor(const Properties &props) : BSDF(props) {
ref<FileResolver> fResolver = Thread::getThread()->getFileResolver();
m_specularReflectance = new ConstantSpectrumTexture(
props.getSpectrum("specularReflectance", Spectrum(1.0f)));
std::string preset = props.getString("preset", "Cu");
Spectrum presetEta, presetK;
presetEta.fromContinuousSpectrum(InterpolatedSpectrum(
fResolver->resolve("data/ior/" + preset + ".eta.spd")));
presetK.fromContinuousSpectrum(InterpolatedSpectrum(
fResolver->resolve("data/ior/" + preset + ".k.spd")));
m_eta = props.getSpectrum("eta", presetEta);
m_k = props.getSpectrum("k", presetK);
m_components.push_back(EDeltaReflection | EFrontSide);
m_usesRayDifferentials = false;
}
SmoothConductor(Stream *stream, InstanceManager *manager)
: BSDF(stream, manager) {
m_specularReflectance = static_cast<Texture *>(manager->getInstance(stream));
m_eta = Spectrum(stream);
m_k = Spectrum(stream);
m_components.push_back(EDeltaReflection | EFrontSide);
m_usesRayDifferentials =
m_specularReflectance->usesRayDifferentials();
}
virtual ~SmoothConductor() { }
void serialize(Stream *stream, InstanceManager *manager) const {
BSDF::serialize(stream, manager);
manager->serialize(stream, m_specularReflectance.get());
m_eta.serialize(stream);
m_k.serialize(stream);
}
void addChild(const std::string &name, ConfigurableObject *child) {
if (child->getClass()->derivesFrom(MTS_CLASS(Texture)) && name == "specularReflectance") {
m_specularReflectance = static_cast<Texture *>(child);
m_usesRayDifferentials |= m_specularReflectance->usesRayDifferentials();
} else {
BSDF::addChild(name, child);
}
}
void configure() {
BSDF::configure();
/* Verify the input parameter and fix them if necessary */
m_specularReflectance = ensureEnergyConservation(
m_specularReflectance, "specularReflectance", 1.0f);
}
/// Reflection in local coordinates
inline Vector reflect(const Vector &wi) const {
return Vector(-wi.x, -wi.y, wi.z);
}
Spectrum eval(const BSDFQueryRecord &bRec, EMeasure measure) const {
bool sampleReflection = (bRec.typeMask & EDeltaReflection)
&& (bRec.component == -1 || bRec.component == 0);
if (!sampleReflection || measure != EDiscrete ||
Frame::cosTheta(bRec.wi) <= 0 ||
Frame::cosTheta(bRec.wo) <= 0)
return Spectrum(0.0f);
return m_specularReflectance->getValue(bRec.its) *
fresnelConductor(Frame::cosTheta(bRec.wi), m_eta, m_k);
}
Float pdf(const BSDFQueryRecord &bRec, EMeasure measure) const {
bool sampleReflection = (bRec.typeMask & EDeltaReflection)
&& (bRec.component == -1 || bRec.component == 0);
if (!sampleReflection || measure != EDiscrete ||
Frame::cosTheta(bRec.wi) <= 0 ||
Frame::cosTheta(bRec.wo) <= 0)
return 0.0f;
return 1.0f;
}
Spectrum sample(BSDFQueryRecord &bRec, const Point2 &sample) const {
bool sampleReflection = (bRec.typeMask & EDeltaReflection)
&& (bRec.component == -1 || bRec.component == 0);
if (!sampleReflection || Frame::cosTheta(bRec.wi) <= 0)
return Spectrum(0.0f);
bRec.sampledComponent = 0;
bRec.sampledType = EDeltaReflection;
bRec.wo = reflect(bRec.wi);
return m_specularReflectance->getValue(bRec.its) *
fresnelConductor(Frame::cosTheta(bRec.wi), m_eta, m_k);
}
Spectrum sample(BSDFQueryRecord &bRec, Float &pdf, const Point2 &sample) const {
bool sampleReflection = (bRec.typeMask & EDeltaReflection)
&& (bRec.component == -1 || bRec.component == 0);
if (!sampleReflection || Frame::cosTheta(bRec.wi) <= 0)
return Spectrum(0.0f);
bRec.sampledComponent = 0;
bRec.sampledType = EDeltaReflection;
bRec.wo = reflect(bRec.wi);
pdf = 1;
return m_specularReflectance->getValue(bRec.its) *
fresnelConductor(Frame::cosTheta(bRec.wi), m_eta, m_k);
}
std::string toString() const {
std::ostringstream oss;
oss << "SmoothConductor[" << endl
<< " eta = " << m_eta.toString() << "," << endl
<< " k = " << m_k.toString() << "," << endl
<< " specularReflectance = " << indent(m_specularReflectance->toString()) << endl
<< "]";
return oss.str();
}
MTS_DECLARE_CLASS()
private:
ref<Texture> m_specularReflectance;
Spectrum m_eta;
Spectrum m_k;
};
MTS_IMPLEMENT_CLASS_S(SmoothConductor, false, BSDF)
MTS_EXPORT_PLUGIN(SmoothConductor, "Smooth conductor");
MTS_NAMESPACE_END
Reference in New Issue View Git Blame Copy Permalink