/**
* 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.framework.random.RandomUtil;
import ca.eandb.jmist.math.HPoint3;
import ca.eandb.jmist.math.MathUtil;
import ca.eandb.jmist.math.Point2;
import ca.eandb.jmist.math.Point3;
import ca.eandb.jmist.math.Ray3;
import ca.eandb.jmist.math.Vector2;
import ca.eandb.jmist.math.Vector3;
/**
* A thin <code>Lens</code>.
* @author Brad Kimmel
*/
public final class ThinLens extends AbstractLens {
/** Serialization version ID. */
private static final long serialVersionUID = -4932532440872351450L;
/** The default field of view (in radians). */
public static final double DEFAULT_FIELD_OF_VIEW = Math.PI / 2.0;
/** The default aspect ratio. */
public static final double DEFAULT_ASPECT_RATIO = 1.0;
/** The default focal length (in meters). */
public static final double DEFAULT_FOCAL_LENGTH = 0.050;
/** The default aperture (f-number). */
public static final double DEFAULT_APERTURE = 3.6;
/** The default distance to the plane in focus (in meters). */
public static final double DEFAULT_FOCUS_DISTANCE = 1.0;
/** The focal length (in meters). */
private final double focalLength;
/** The aperture (f-number). */
private final double aperture;
/** The distance to the plane in focus (in meters). */
private final double focusDistance;
/** The field of view (in radians). */
private final double fov;
/** The aspect ratio. */
private final double aspect;
/** The radius of the aperture (in meters). */
private final double apertureRadius;
/** The area of the aperture (in meters squared). */
private final double apertureArea;
/** The width of the virtual screen at the focus distance (in meters). */
private final double objPlaneWidth;
/** The height of the virtual screen at the focus distance (in meters). */
private final double objPlaneHeight;
/**
* Creates a new <code>ThinLens</code>.
*/
public ThinLens() {
this.focalLength = DEFAULT_FOCAL_LENGTH;
this.aperture = DEFAULT_APERTURE;
this.focusDistance = DEFAULT_FOCUS_DISTANCE;
this.fov = DEFAULT_FIELD_OF_VIEW;
this.aspect = DEFAULT_ASPECT_RATIO;
this.apertureRadius = 0.5 * focalLength / aperture;
this.apertureArea = Math.PI * apertureRadius * apertureRadius;
this.objPlaneWidth = 2.0 * focusDistance * Math.tan(fov / 2.0);
this.objPlaneHeight = objPlaneWidth / aspect;
}
/**
* Creates a new <code>ThinLens</code>.
* @param focalLength The focal length (in meters).
* @param aperture The aperture (f-number).
* @param focusDistance The distance to the plane in focus (in meters).
* @param fov The field of view (in radians).
* @param aspect The aspect ratio.
*/
public ThinLens(double focalLength, double aperture, double focusDistance, double fov, double aspect) {
this.focalLength = focalLength;
this.aperture = aperture;
this.focusDistance = focusDistance;
this.fov = fov;
this.aspect = aspect;
this.apertureRadius = 0.5 * focalLength / aperture;
this.apertureArea = Math.PI * apertureRadius * apertureRadius;
this.objPlaneWidth = 2.0 * focusDistance * Math.tan(fov / 2.0);
this.objPlaneHeight = objPlaneWidth / aspect;
}
/* (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>ThinLens</code>.
*/
private final class Node extends EyeTerminalNode {
/** Projected point on the image plane. */
private final Point2 pointOnImagePlane;
private final Ray3 ray;
public Node(Point2 p, PathInfo pathInfo, double ru, double rv, double rj) {
super(pathInfo, ru, rv, rj);
this.pointOnImagePlane = p;
Vector2 uv = RandomUtil.uniformOnDisc(apertureRadius, ru, rv).toCartesian();
Point3 origin = new Point3(uv.x(), uv.y(), 0.0);
Point3 focus = new Point3(
(pointOnImagePlane.x() - 0.5) * objPlaneWidth,
(0.5 - pointOnImagePlane.y()) * objPlaneHeight,
-focusDistance);
Vector3 direction = origin.unitVectorTo(focus);
this.ray = new Ray3(origin, direction);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.EyeNode#project(ca.eandb.jmist.math.HPoint3)
*/
@Override
public Point2 project(HPoint3 p) {
Ray3 pray = new Ray3(ray.origin(), p);
Vector3 dir = pray.direction();
if (-dir.z() < MathUtil.EPSILON) {
return null;
}
double ratio = -focusDistance / dir.z();
double x = ray.origin().x() + ratio * dir.x();
double y = ray.origin().y() + ratio * dir.y();
final double u = 0.5 + x / objPlaneWidth;
if (!MathUtil.inRangeCC(u, 0.0, 1.0)) {
return null;
}
final double v = 0.5 - y / objPlaneHeight;
if (!MathUtil.inRangeCC(v, 0.0, 1.0)) {
return null;
}
return new Point2(u, v);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#getPDF()
*/
@Override
public double getPDF() {
return 1.0 / apertureArea;
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#isSpecular()
*/
@Override
public boolean isSpecular() {
return false;
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#getPosition()
*/
@Override
public HPoint3 getPosition() {
return ray.origin();
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#sample(double, double, double)
*/
@Override
public ScatteredRay sample(double ru, double rv, double rj) {
Vector3 v = ray.direction();
Color color = getWhite();
double pdf = (focusDistance * focusDistance)
/ (v.z() * v.z() * v.z() * v.z() * objPlaneWidth * objPlaneHeight);
return ScatteredRay.diffuse(ray, color, pdf);
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#scatter(ca.eandb.jmist.math.Vector3)
*/
@Override
public Color scatter(Vector3 v) {
return getGray(getPDF(v));
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#getCosine(ca.eandb.jmist.math.Vector3)
*/
@Override
public double getCosine(Vector3 v) {
return -v.z() / v.length();
}
/* (non-Javadoc)
* @see ca.eandb.jmist.framework.path.PathNode#getPDF(ca.eandb.jmist.math.Vector3)
*/
@Override
public double getPDF(Vector3 v) {
v = v.unit();
return (focusDistance * focusDistance)
/ (v.z() * v.z() * v.z() * v.z() * objPlaneWidth * objPlaneHeight);
}
}
}