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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 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
     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      */
     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      */
     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      */
     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      */
    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      */
    128     public float getInvRadius() {
    129         return invRadius;
    130     }
    131 
    132     @Override
    133     public Light.Type getType() {
    134         return Light.Type.Point;
    135     }
    136 
    137     @Override
    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
    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