/**
* 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.shader;
import java.io.IOException;
import java.io.ObjectInputStream;
import ca.eandb.jmist.framework.Random;
import ca.eandb.jmist.framework.ScatteredRay;
import ca.eandb.jmist.framework.Shader;
import ca.eandb.jmist.framework.ShadingContext;
import ca.eandb.jmist.framework.color.Color;
import ca.eandb.jmist.framework.color.ColorUtil;
import ca.eandb.jmist.framework.color.WavelengthPacket;
import ca.eandb.jmist.framework.random.NRooksRandom;
import ca.eandb.jmist.framework.random.RandomUtil;
import ca.eandb.jmist.framework.random.SimpleRandom;
/**
* A <code>Shader</code> that traces up to one randomly selected scattered ray.
* @author Brad Kimmel
*/
public final class PathTracingShader implements Shader {
/** Serialization version ID. */
private static final long serialVersionUID = -3619786295095920623L;
/** The default maximum path depth. */
private static final int DEFAULT_MAX_DEPTH = 10;
private static final int DEFAULT_FIRST_BOUNCE_RAYS = 1;
/** The maximum path depth. */
private final int maxDepth;
private final int firstBounceRays;
private transient ThreadLocal<Random> rnd;
private transient ThreadLocal<Random> firstBounceSampler;
/**
* Creates a new <code>PathTracingShader</code>.
*/
public PathTracingShader() {
this(DEFAULT_MAX_DEPTH, DEFAULT_FIRST_BOUNCE_RAYS);
}
/**
* Creates a new <code>PathTracingShader</code>.
* @param maxDepth The maximum path depth.
*/
public PathTracingShader(int maxDepth) {
this(maxDepth, DEFAULT_FIRST_BOUNCE_RAYS);
}
/**
* Creates a new <code>PathTracingShader</code>.
* @param maxDepth The maximum path depth.
* @param firstBounceRays The number of secondary rays to cast on the first
* bounce.
*/
public PathTracingShader(int maxDepth, int firstBounceRays) {
this.maxDepth = maxDepth;
this.firstBounceRays = firstBounceRays;
initialize();
}
/** Sets up the random number generated used by this shader. */
private void initialize() {
rnd = new ThreadLocal<Random>() {
protected Random initialValue() {
return new SimpleRandom();
}
};
if (firstBounceRays > 0) {
firstBounceSampler = new ThreadLocal<Random>() {
protected Random initialValue() {
return new NRooksRandom(firstBounceRays, 3, rnd.get());
}
};
}
}
private void readObject(ObjectInputStream ois)
throws ClassNotFoundException, IOException {
ois.defaultReadObject();
initialize();
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.Shader#shade(ca.eandb.jmist.framework.ShadingContext)
*/
public Color shade(ShadingContext sc) {
if (firstBounceRays > 0 && sc.getPathDepth() < 1) {
Random sampler = firstBounceSampler.get();
WavelengthPacket lambda = sc.getWavelengthPacket();
Color shade = sc.getColorModel().getBlack(lambda);
for (int i = 0; i < firstBounceRays; i++) {
ScatteredRay ray = sc.getMaterial().scatter(sc, sc.getIncident(), true, sc.getWavelengthPacket(), sampler.next(), sampler.next(), sampler.next());
if (ray != null) {
shade = shade.plus(sc.castRay(ray).times(ray.getColor()));
}
}
return shade.divide(firstBounceRays);
} else if (sc.getPathDepth() < maxDepth) {
ScatteredRay ray = sc.getScatteredRay();
if (ray != null) {
double prob = ColorUtil.getMeanChannelValue(ray.getColor());
if (prob < 1.0) {
if (RandomUtil.bernoulli(prob, rnd.get())) {
ray = ScatteredRay.select(ray, prob);
} else {
ray = null;
}
}
if (ray != null) {
return sc.castRay(ray).times(ray.getColor());
}
}
}
WavelengthPacket lambda = sc.getWavelengthPacket();
return sc.getColorModel().getBlack(lambda);
}
}