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 package com.jme3.light;
33 
34 import com.jme3.bounding.BoundingVolume;
35 import com.jme3.export.InputCapsule;
36 import com.jme3.export.JmeExporter;
37 import com.jme3.export.JmeImporter;
38 import com.jme3.export.OutputCapsule;
39 import com.jme3.math.Vector3f;
40 import com.jme3.scene.Spatial;
41 import java.io.IOException;
42 
43 /**
44  * Represents a point light.
45  * A point light emits light from a given position into all directions in space.
46  * E.g a lamp or a bright effect. Point light positions are in world space.
47  * <p>
48  * In addition to a position, point lights also have a radius which
49  * can be used to attenuate the influence of the light depending on the
50  * distance between the light and the effected object.
51  *
52  */
53 public class PointLight extends Light {
54 
55     protected Vector3f position = new Vector3f();
56     protected float radius = 0;
57     protected float invRadius = 0;
58 
59     @Override
computeLastDistance(Spatial owner)60     public void computeLastDistance(Spatial owner) {
61         if (owner.getWorldBound() != null) {
62             BoundingVolume bv = owner.getWorldBound();
63             lastDistance = bv.distanceSquaredTo(position);
64         } else {
65             lastDistance = owner.getWorldTranslation().distanceSquared(position);
66         }
67     }
68 
69     /**
70      * Returns the world space position of the light.
71      *
72      * @return the world space position of the light.
73      *
74      * @see PointLight#setPosition(com.jme3.math.Vector3f)
75      */
getPosition()76     public Vector3f getPosition() {
77         return position;
78     }
79 
80     /**
81      * Set the world space position of the light.
82      *
83      * @param position the world space position of the light.
84      */
setPosition(Vector3f position)85     public void setPosition(Vector3f position) {
86         this.position.set(position);
87     }
88 
89     /**
90      * Returns the radius of the light influence. A radius of 0 means
91      * the light has no attenuation.
92      *
93      * @return the radius of the light
94      */
getRadius()95     public float getRadius() {
96         return radius;
97     }
98 
99     /**
100      * Set the radius of the light influence.
101      * <p>
102      * Setting a non-zero radius indicates the light should use attenuation.
103      * If a pixel's distance to this light's position
104      * is greater than the light's radius, then the pixel will not be
105      * effected by this light, if the distance is less than the radius, then
106      * the magnitude of the influence is equal to distance / radius.
107      *
108      * @param radius the radius of the light influence.
109      *
110      * @throws IllegalArgumentException If radius is negative
111      */
setRadius(float radius)112     public void setRadius(float radius) {
113         if (radius < 0) {
114             throw new IllegalArgumentException("Light radius cannot be negative");
115         }
116         this.radius = radius;
117         if(radius!=0){
118             this.invRadius = 1 / radius;
119         }else{
120             this.invRadius = 0;
121         }
122     }
123 
124     /**
125      * for internal use only
126      * @return the inverse of the radius
127      */
getInvRadius()128     public float getInvRadius() {
129         return invRadius;
130     }
131 
132     @Override
getType()133     public Light.Type getType() {
134         return Light.Type.Point;
135     }
136 
137     @Override
write(JmeExporter ex)138     public void write(JmeExporter ex) throws IOException {
139         super.write(ex);
140         OutputCapsule oc = ex.getCapsule(this);
141         oc.write(position, "position", null);
142         oc.write(radius, "radius", 0f);
143     }
144 
145     @Override
read(JmeImporter im)146     public void read(JmeImporter im) throws IOException {
147         super.read(im);
148         InputCapsule ic = im.getCapsule(this);
149         position = (Vector3f) ic.readSavable("position", null);
150         radius = ic.readFloat("radius", 0f);
151         if(radius!=0){
152             this.invRadius = 1 / radius;
153         }else{
154             this.invRadius = 0;
155         }
156     }
157 }
158