/**
* 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.biospec;
import ca.eandb.jmist.framework.ScatteredRay;
import ca.eandb.jmist.framework.SurfacePoint;
import ca.eandb.jmist.framework.color.WavelengthPacket;
import ca.eandb.jmist.framework.material.OpaqueMaterial;
import ca.eandb.jmist.framework.random.RandomUtil;
import ca.eandb.jmist.math.Basis3;
import ca.eandb.jmist.math.Optics;
import ca.eandb.jmist.math.Ray3;
import ca.eandb.jmist.math.SphericalCoordinates;
import ca.eandb.jmist.math.Vector3;
/**
* @author bwkimmel
*
*/
public final class TrowbridgeReitzMaterial extends OpaqueMaterial {
/** Serialization version ID. */
private static final long serialVersionUID = 1839137815524190898L;
private final double oblateness;
private final double riBelow;
private final double riAbove;
/**
* @param riBelow
* @param riAbove
*/
public TrowbridgeReitzMaterial(double oblateness, double riBelow, double riAbove) {
this.oblateness = oblateness;
this.riBelow = riBelow;
this.riAbove = riAbove;
}
/* (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) {
double n1 = riAbove;
double n2 = riBelow;
Vector3 N = x.getNormal();
double R = Optics.reflectance(v, n1, n2, N);
if (RandomUtil.bernoulli(R, rj)) {
Basis3 basis = x.getBasis();
double sigma2 = oblateness * oblateness;
double sigma4 = sigma2 * sigma2;
Vector3 out;
double theta = Math.acos(Math.sqrt(((sigma2 / Math.sqrt(sigma4 + (1.0 - sigma4) * ru)) - 1.0) / (sigma2 - 1.0)));
double phi = 2.0 * Math.PI * rv;
SphericalCoordinates sc = new SphericalCoordinates(theta, phi);
Vector3 microN = sc.toCartesian(basis);
out = Optics.reflect(v, microN);
if (out.dot(N) <= 0.0) {
return null;
}
return ScatteredRay.diffuse(new Ray3(x.getPosition(), out), lambda.getColorModel().getWhite(lambda), 1.0);
} else {
v = Optics.refract(v, n1, n2, N);
return ScatteredRay.transmitDiffuse(new Ray3(x.getPosition(), v), lambda.getColorModel().getWhite(lambda), 1.0);
}
}
}