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      1 /*
      2  * Copyright (c) 2009-2010 jMonkeyEngine
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are
      7  * met:
      8  *
      9  * * Redistributions of source code must retain the above copyright
     10  *   notice, this list of conditions and the following disclaimer.
     11  *
     12  * * Redistributions in binary form must reproduce the above copyright
     13  *   notice, this list of conditions and the following disclaimer in the
     14  *   documentation and/or other materials provided with the distribution.
     15  *
     16  * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
     17  *   may be used to endorse or promote products derived from this software
     18  *   without specific prior written permission.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     21  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     23  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
     24  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     25  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     26  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     27  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
     28  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
     29  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
     30  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 package com.jme3.math;
     34 
     35 import com.jme3.export.*;
     36 import java.io.IOException;
     37 
     38 
     39 /**
     40  * <code>Ring</code> defines a flat ring or disk within three dimensional
     41  * space that is specified via the ring's center point, an up vector, an inner
     42  * radius, and an outer radius.
     43  *
     44  * @author Andrzej Kapolka
     45  * @author Joshua Slack
     46  */
     47 
     48 public final class Ring implements Savable, Cloneable, java.io.Serializable {
     49 
     50     static final long serialVersionUID = 1;
     51 
     52     private Vector3f center, up;
     53     private float innerRadius, outerRadius;
     54     private transient static Vector3f b1 = new Vector3f(), b2 = new Vector3f();
     55 
     56     /**
     57      * Constructor creates a new <code>Ring</code> lying on the XZ plane,
     58      * centered at the origin, with an inner radius of zero and an outer radius
     59      * of one (a unit disk).
     60      */
     61     public Ring() {
     62         center = new Vector3f();
     63         up = Vector3f.UNIT_Y.clone();
     64         innerRadius = 0f;
     65         outerRadius = 1f;
     66     }
     67 
     68     /**
     69      * Constructor creates a new <code>Ring</code> with defined center point,
     70      * up vector, and inner and outer radii.
     71      *
     72      * @param center
     73      *            the center of the ring.
     74      * @param up
     75      *            the unit up vector defining the ring's orientation.
     76      * @param innerRadius
     77      *            the ring's inner radius.
     78      * @param outerRadius
     79      *            the ring's outer radius.
     80      */
     81     public Ring(Vector3f center, Vector3f up, float innerRadius,
     82             float outerRadius) {
     83         this.center = center;
     84         this.up = up;
     85         this.innerRadius = innerRadius;
     86         this.outerRadius = outerRadius;
     87     }
     88 
     89     /**
     90      * <code>getCenter</code> returns the center of the ring.
     91      *
     92      * @return the center of the ring.
     93      */
     94     public Vector3f getCenter() {
     95         return center;
     96     }
     97 
     98     /**
     99      * <code>setCenter</code> sets the center of the ring.
    100      *
    101      * @param center
    102      *            the center of the ring.
    103      */
    104     public void setCenter(Vector3f center) {
    105         this.center = center;
    106     }
    107 
    108     /**
    109      * <code>getUp</code> returns the ring's up vector.
    110      *
    111      * @return the ring's up vector.
    112      */
    113     public Vector3f getUp() {
    114         return up;
    115     }
    116 
    117     /**
    118      * <code>setUp</code> sets the ring's up vector.
    119      *
    120      * @param up
    121      *            the ring's up vector.
    122      */
    123     public void setUp(Vector3f up) {
    124         this.up = up;
    125     }
    126 
    127     /**
    128      * <code>getInnerRadius</code> returns the ring's inner radius.
    129      *
    130      * @return the ring's inner radius.
    131      */
    132     public float getInnerRadius() {
    133         return innerRadius;
    134     }
    135 
    136     /**
    137      * <code>setInnerRadius</code> sets the ring's inner radius.
    138      *
    139      * @param innerRadius
    140      *            the ring's inner radius.
    141      */
    142     public void setInnerRadius(float innerRadius) {
    143         this.innerRadius = innerRadius;
    144     }
    145 
    146     /**
    147      * <code>getOuterRadius</code> returns the ring's outer radius.
    148      *
    149      * @return the ring's outer radius.
    150      */
    151     public float getOuterRadius() {
    152         return outerRadius;
    153     }
    154 
    155     /**
    156      * <code>setOuterRadius</code> sets the ring's outer radius.
    157      *
    158      * @param outerRadius
    159      *            the ring's outer radius.
    160      */
    161     public void setOuterRadius(float outerRadius) {
    162         this.outerRadius = outerRadius;
    163     }
    164 
    165     /**
    166      *
    167      * <code>random</code> returns a random point within the ring.
    168      *
    169      * @return a random point within the ring.
    170      */
    171     public Vector3f random() {
    172         return random(null);
    173     }
    174 
    175     /**
    176      *
    177      * <code>random</code> returns a random point within the ring.
    178      *
    179      * @param result Vector to store result in
    180      * @return a random point within the ring.
    181      */
    182     public Vector3f random(Vector3f result) {
    183         if (result == null) {
    184             result = new Vector3f();
    185         }
    186 
    187         // compute a random radius according to the ring area distribution
    188         float inner2 = innerRadius * innerRadius, outer2 = outerRadius
    189                 * outerRadius, r = FastMath.sqrt(inner2
    190                 + FastMath.nextRandomFloat() * (outer2 - inner2)), theta = FastMath
    191                 .nextRandomFloat()
    192                 * FastMath.TWO_PI;
    193         up.cross(Vector3f.UNIT_X, b1);
    194         if (b1.lengthSquared() < FastMath.FLT_EPSILON) {
    195             up.cross(Vector3f.UNIT_Y, b1);
    196         }
    197         b1.normalizeLocal();
    198         up.cross(b1, b2);
    199         result.set(b1).multLocal(r * FastMath.cos(theta)).addLocal(center);
    200         result.scaleAdd(r * FastMath.sin(theta), b2, result);
    201         return result;
    202     }
    203 
    204     public void write(JmeExporter e) throws IOException {
    205         OutputCapsule capsule = e.getCapsule(this);
    206         capsule.write(center, "center", Vector3f.ZERO);
    207         capsule.write(up, "up", Vector3f.UNIT_Z);
    208         capsule.write(innerRadius, "innerRadius", 0f);
    209         capsule.write(outerRadius, "outerRadius", 1f);
    210     }
    211 
    212     public void read(JmeImporter e) throws IOException {
    213         InputCapsule capsule = e.getCapsule(this);
    214         center = (Vector3f) capsule.readSavable("center",
    215                 Vector3f.ZERO.clone());
    216         up = (Vector3f) capsule
    217                 .readSavable("up", Vector3f.UNIT_Z.clone());
    218         innerRadius = capsule.readFloat("innerRadius", 0f);
    219         outerRadius = capsule.readFloat("outerRadius", 1f);
    220     }
    221 
    222     @Override
    223     public Ring clone() {
    224         try {
    225             Ring r = (Ring) super.clone();
    226             r.center = center.clone();
    227             r.up = up.clone();
    228             return r;
    229         } catch (CloneNotSupportedException e) {
    230             throw new AssertionError();
    231         }
    232     }
    233 }