/**
* Java Modular Image Synthesis Toolkit (JMIST)
* Copyright (C) 2008-2013 Bradley W. Kimmel
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
package ca.eandb.jmist.framework.material;
import ca.eandb.jmist.framework.ScatteredRay;
import ca.eandb.jmist.framework.SurfacePoint;
import ca.eandb.jmist.framework.color.Color;
import ca.eandb.jmist.framework.color.WavelengthPacket;
import ca.eandb.jmist.framework.material.support.IsotropicMicrofacetModel;
import ca.eandb.jmist.framework.random.RandomUtil;
import ca.eandb.jmist.math.Optics;
import ca.eandb.jmist.math.Point3;
import ca.eandb.jmist.math.Ray3;
import ca.eandb.jmist.math.Vector3;
/**
* A <code>Material</code> representing a dielectric material having a rough
* surface, based on:
*
* B. Walter, S.R. Marschner, H. Li, K.E. Torrance, "Microfacet models for
* reflection through rough surfaces", In proceedings of Eurographics Symposium
* on Rendering, 2007.
*
* @author Brad Kimmel
*/
public final class RoughDielectricMaterial extends AbstractMaterial {
/** Serialization version ID */
private static final long serialVersionUID = -2137062689589252464L;
private final double n1;
private final double n2;
private final IsotropicMicrofacetModel microfacets;
public RoughDielectricMaterial(double n2, IsotropicMicrofacetModel microfacets) {
this(1.0, n2, microfacets);
}
public RoughDielectricMaterial(double n1, double n2, IsotropicMicrofacetModel microfacets) {
this.n1 = n1;
this.n2 = n2;
this.microfacets = microfacets;
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.Medium#extinctionIndex(ca.eandb.jmist.math.Point3, ca.eandb.jmist.framework.color.WavelengthPacket)
*/
@Override
public Color extinctionIndex(Point3 p, WavelengthPacket lambda) {
return lambda.getColorModel().getBlack(lambda);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.Medium#refractiveIndex(ca.eandb.jmist.math.Point3, ca.eandb.jmist.framework.color.WavelengthPacket)
*/
@Override
public Color refractiveIndex(Point3 p, WavelengthPacket lambda) {
return lambda.getColorModel().getGray(n2, lambda);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.Medium#transmittance(ca.eandb.jmist.math.Ray3, double, ca.eandb.jmist.framework.color.WavelengthPacket)
*/
@Override
public Color transmittance(Ray3 ray, double distance,
WavelengthPacket lambda) {
return lambda.getColorModel().getWhite(lambda);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.material.AbstractMaterial#bsdf(ca.eandb.jmist.framework.SurfacePoint, ca.eandb.jmist.math.Vector3, ca.eandb.jmist.math.Vector3, ca.eandb.jmist.framework.color.WavelengthPacket)
*/
@Override
public Color bsdf(SurfacePoint x, Vector3 in, Vector3 out,
WavelengthPacket lambda) {
return lambda.getColorModel().getGray(bsdf(x, in, out), lambda);
}
public double bsdf(SurfacePoint x, Vector3 in, Vector3 out) {
Vector3 n = x.getNormal();
double ndoti = -n.dot(in);
double ndoto = n.dot(out);
return (ndoti > 0.0) == (ndoto > 0.0)
? brdf(x, in, out, n)
: btdf(x, in, out, n);
}
private double brdf(SurfacePoint x, Vector3 in, Vector3 out, Vector3 n) {
double ndoti = -n.dot(in);
double ndoto = n.dot(out);
/* Eq. (13) */
Vector3 hr = out.minus(in).times(Math.signum(ndoti)).unit();
hr = hr.dot(n) > 0.0 ? hr : hr.opposite();
double g = microfacets.getShadowingAndMasking(in, out, hr, n);
double d = microfacets.getDistributionPDF(hr, n);
double f = Optics.reflectance(in, n1, n2, hr);
/* Eq. (20) */
return f * g * d / (4.0 * Math.abs(ndoti * ndoto));
}
private double btdf(SurfacePoint x, Vector3 in, Vector3 out, Vector3 n) {
double ndoti = -n.dot(in);
double ni, no;
if (ndoti > 0.0) {
ni = n1;
no = n2;
} else {
ni = n2;
no = n1;
}
/* Eq. (16) */
Vector3 ht = in.times(ni).minus(out.times(no)).unit();
ht = ht.dot(n) > 0.0 ? ht : ht.opposite();
double hdoti = -ht.dot(in);
double hdoto = ht.dot(out);
double ndoto = n.dot(out);
double k = Math.abs(hdoti * hdoto / (ndoti * ndoto));
double c = ni * hdoti + no * hdoto;
double f = Optics.reflectance(in, n1, n2, ht);
double g = microfacets.getShadowingAndMasking(in, out, ht, n);
double d = microfacets.getDistributionPDF(ht, n);
/* Eq. (21) */
return k * no * no * (1.0 - f) * g * d / (c * c);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.material.AbstractMaterial#getScatteringPDF(ca.eandb.jmist.framework.SurfacePoint, ca.eandb.jmist.math.Vector3, ca.eandb.jmist.math.Vector3, boolean, ca.eandb.jmist.framework.color.WavelengthPacket)
*/
@Override
public double getScatteringPDF(SurfacePoint x, Vector3 in, Vector3 out,
boolean adjoint, WavelengthPacket lambda) {
Vector3 n = x.getNormal();
double ndoti = -n.dot(in);
double ndoto = n.dot(out);
boolean reflected = (ndoti / ndoto) > 0.0;
if (reflected) {
Vector3 hr = out.minus(in).times(Math.signum(ndoti)).unit();
hr = hr.dot(n) > 0.0 ? hr : hr.opposite();
double partial = 1.0 / (4.0 * Math.abs(hr.dot(out)));
double d = microfacets.getDistributionPDF(hr, n);
double pm = d * Math.abs(hr.dot(n));
double po = pm * partial;
return po;// / Math.abs(n.dot(out));
} else {
double ni, no;
if (ndoti > 0.0) {
ni = n1;
no = n2;
} else {
ni = n2;
no = n1;
}
//Vector3 ht = out.times(no).minus(in.times(ni)).unit();
Vector3 ht = in.times(ni).minus(out.times(no)).unit();
ht = ht.dot(n) > 0.0 ? ht : ht.opposite();
double hdoti = -ht.dot(in);
double hdoto = ht.dot(out);
double k = Math.abs(hdoti * hdoto / (ndoti * ndoto));
double c = ni * hdoti + no * hdoto;
double partial = no * no * Math.abs(hdoto) / (c * c);
double d = microfacets.getDistributionPDF(ht, n);
double pm = d * Math.abs(ht.dot(n));
double po = pm * partial;
return po;// / Math.abs(n.dot(out));
}
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.material.AbstractMaterial#scatter(ca.eandb.jmist.framework.SurfacePoint, ca.eandb.jmist.math.Vector3, boolean, ca.eandb.jmist.framework.color.WavelengthPacket, double, double, double)
*/
@Override
public ScatteredRay scatter(SurfacePoint x, Vector3 v, boolean adjoint,
WavelengthPacket lambda, double ru, double rv, double rj) {
Vector3 n = x.getNormal();
Vector3 m = microfacets.sample(ru, rv).toCartesian(x.getBasis());
double mdoti = Math.abs(m.dot(v));
double ndoti = Math.abs(n.dot(v));
double mdotn = Math.abs(m.dot(n));
double ni = -v.dot(n) >= 0.0 ? n1 : n2;
double nt = -v.dot(n) >= 0.0 ? n2 : n1;
double r = Optics.reflectance(v, n1, n2, m.dot(n) > 0.0 ? m : m.opposite());
boolean reflected = RandomUtil.bernoulli(r, rj);
Vector3 out = reflected ? Optics.reflect(v, m) : Optics.refract(v, n1, n2, m);
double g = microfacets.getShadowingAndMasking(v, out, m, n);
double weight = (mdoti / (ndoti * mdotn)) * g;
double pdf = getScatteringPDF(x, v, out, adjoint, lambda);
return new ScatteredRay(new Ray3(x.getPosition(), out), lambda.getColorModel().getGray(weight, lambda), ScatteredRay.Type.GLOSSY, pdf, !reflected);
}
}