/**
* 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.scatter;
import ca.eandb.jmist.framework.Function1;
import ca.eandb.jmist.framework.Random;
import ca.eandb.jmist.framework.SurfacePointGeometry;
import ca.eandb.jmist.framework.function.ConstantFunction1;
import ca.eandb.jmist.framework.random.RandomUtil;
import ca.eandb.jmist.math.Vector3;
/**
* A <code>SurfaceScatterer</code> representing a Lambertian surface.
* @see <a href="http://en.wikipedia.org/wiki/Lambertian_reflectance">Lambertian reflectance (wikipedia)</a>
* @author Brad Kimmel
*/
public final class LambertianSurfaceScatterer implements SurfaceScatterer {
/** Serialization version ID. */
private static final long serialVersionUID = 6806933821578898186L;
/** The reflectance of the surface. */
private final Function1 reflectance;
/** The transmittance of the surface. */
private final Function1 transmittance;
/**
* Creates a new <code>LambertianSurfaceScatterer</code>.
* @param reflectance The reflectance of the surface.
* @param transmittance The transmittance of the surface.
*/
public LambertianSurfaceScatterer(Function1 reflectance, Function1 transmittance) {
this.reflectance = reflectance;
this.transmittance = transmittance;
}
/**
* Creates a new <code>LambertianSurfaceScatterer</code>.
* @param reflectance The reflectance of the surface.
*/
public LambertianSurfaceScatterer(Function1 reflectance) {
this(reflectance, Function1.ZERO);
}
/**
* Creates a new <code>LambertianSurfaceScatterer</code>.
* @param reflectance The reflectance of the surface.
* @param transmittance The transmittance of the surface.
*/
public LambertianSurfaceScatterer(double reflectance, double transmittance) {
this(new ConstantFunction1(reflectance), new ConstantFunction1(transmittance));
}
/**
* Creates a new <code>LambertianSurfaceScatterer</code>.
* @param reflectance The reflectance of the surface.
*/
public LambertianSurfaceScatterer(double reflectance) {
this(new ConstantFunction1(reflectance));
}
/**
* Creates a new <code>LambertianSurfaceScatterer</code> with unit
* reflectance.
*/
public LambertianSurfaceScatterer() {
this(Function1.ONE, Function1.ZERO);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.scatter.SurfaceScatterer#scatter(ca.eandb.jmist.framework.SurfacePointGeometry, ca.eandb.jmist.math.Vector3, boolean, ca.eandb.jmist.framework.color.WavelengthPacket, ca.eandb.jmist.framework.Random)
*/
public Vector3 scatter(SurfacePointGeometry x, Vector3 v,
boolean adjoint, double lambda, Random rnd) {
double r = reflectance.evaluate(lambda);
double u = rnd.next() - r;
if (u < 0.0) {
Vector3 out = RandomUtil.diffuse(rnd).toCartesian(x.getBasis());
return (v.dot(x.getNormal()) < 0.0) ? out : out.opposite();
}
double t = transmittance.evaluate(lambda);
u -= t;
if (u < 0.0) {
Vector3 out = RandomUtil.diffuse(rnd).toCartesian(x.getBasis());
return (v.dot(x.getNormal()) < 0.0) ? out.opposite() : out;
}
return null;
}
}