/**
* 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.lens;
import ca.eandb.jmist.framework.ScatteredRay;
import ca.eandb.jmist.framework.color.Color;
import ca.eandb.jmist.framework.path.EyeNode;
import ca.eandb.jmist.framework.path.EyeTerminalNode;
import ca.eandb.jmist.framework.path.PathInfo;
import ca.eandb.jmist.math.HPoint3;
import ca.eandb.jmist.math.Point2;
import ca.eandb.jmist.math.Point3;
import ca.eandb.jmist.math.Ray3;
import ca.eandb.jmist.math.Vector3;
/**
* A <code>Lens</code> that projects the scene onto a cylindrical virtual
* screen.
* @author Brad Kimmel
*/
public final class PanoramicLens extends AbstractLens {
/** Serialization version ID. */
private static final long serialVersionUID = 9079096932171202826L;
/** The default horizontal field of view (in radians). */
public static final double DEFAULT_HORIZONTAL_FIELD_OF_VIEW = Math.PI;
/** The default vertical field of view (in radians). */
public static final double DEFAULT_VERTICAL_FIELD_OF_VIEW = Math.PI / 2.0;
/** Horizontal field of view (in radians). */
private final double hfov;
/** Height of the virtual image plane. */
private final double height;
/**
* Creates a new <code>PanoramicLens</code>.
*/
public PanoramicLens() {
this(DEFAULT_HORIZONTAL_FIELD_OF_VIEW, DEFAULT_VERTICAL_FIELD_OF_VIEW);
}
/**
* Creates a new <code>PanoramicLens</code>.
* @param hfov The horizontal field of view (in radians).
*/
public PanoramicLens(double hfov) {
this(hfov, DEFAULT_VERTICAL_FIELD_OF_VIEW);
}
/**
* Creates a new <code>PanoramicLens</code>.
* @param hfov The horizontal field of view (in radians).
* @param vfov The vertical field of view (in radians).
*/
public PanoramicLens(double hfov, double vfov) {
this.hfov = hfov;
this.height = 2.0 * Math.tan(vfov / 2.0);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.Lens#sample(ca.eandb.jmist.math.Point2, ca.eandb.jmist.framework.path.PathInfo, double, double, double)
*/
@Override
public EyeNode sample(Point2 p, PathInfo pathInfo, double ru, double rv,
double rj) {
return new Node(p, pathInfo, ru, rv, rj);
}
/**
* An <code>EyeNode</code> generated by a <code>PanoramicLens</code>.
*/
private final class Node extends EyeTerminalNode {
/** Projected point on the image plane. */
private final Point2 pointOnImagePlane;
/**
* Creates a <code>Node</code>.
* @param pointOnImagePlane The <code>Point2</code> on the image plane.
* @param pathInfo The <code>PathInfo</code> describing the context for
* this node.
*/
public Node(Point2 pointOnImagePlane, PathInfo pathInfo, double ru, double rv, double rj) {
super(pathInfo, ru, rv, rj);
this.pointOnImagePlane = pointOnImagePlane;
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.EyeNode#sample(ca.eandb.jmist.math.Point2, ca.eandb.jmist.framework.Random)
*/
public ScatteredRay sample(double ru, double rv, double rj) {
Point2 p = pointOnImagePlane;
double theta = (p.x() - 0.5) * hfov;
Vector3 v = new Vector3(
Math.sin(theta),
(0.5 - p.y()) * height,
-Math.cos(theta));
double r = v.length();
Ray3 ray = new Ray3(Point3.ORIGIN, v.divide(r));
Color color = getWhite();
double pdf = (r * r * r * r) / (hfov * height);
return ScatteredRay.diffuse(ray, color, pdf);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#scatterTo(ca.eandb.jmist.framework.path.PathNode)
*/
public Color scatter(Vector3 v) {
return getGray(getPDF(v));
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.EyeNode#project(ca.eandb.jmist.math.HPoint3)
*/
public Point2 project(HPoint3 x) {
Ray3 ray = new Ray3(Point3.ORIGIN, x);
Vector3 v = ray.direction();
double theta = Math.atan2(v.x(), -v.z());
if (Math.abs(theta) > 0.5 * hfov) {
return null;
}
double h = v.y() / Math.hypot(v.x(), v.z());
if (Math.abs(h) > 0.5 * height) {
return null;
}
return new Point2(
0.5 + theta / hfov,
0.5 - h / height);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#getCosine(ca.eandb.jmist.math.Vector3)
*/
public double getCosine(Vector3 v) {
return Math.hypot(v.x(), v.z()) / v.length();
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#getPosition()
*/
public HPoint3 getPosition() {
return Point3.ORIGIN;
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#getPDF()
*/
public double getPDF() {
return 1.0;
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#isSpecular()
*/
public boolean isSpecular() {
return true;
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#getPDF(ca.eandb.jmist.math.Vector3)
*/
public double getPDF(Vector3 v) {
double theta = Math.atan2(v.x(), -v.z());
if (Math.abs(theta) > 0.5 * hfov) {
return 0.0;
}
double h = v.y() / Math.hypot(v.x(), v.z());
if (Math.abs(h) > 0.5 * height) {
return 0.0;
}
double u = getCosine(v);
return 1.0 / (u * u * u * u * hfov * height);
}
}
}