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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.renderer.queue;
34 
35 import com.jme3.math.Vector3f;
36 import com.jme3.renderer.Camera;
37 import com.jme3.scene.Geometry;
38 
39 public class TransparentComparator implements GeometryComparator {
40 
41     private Camera cam;
42     private final Vector3f tempVec = new Vector3f();
43 
setCamera(Camera cam)44     public void setCamera(Camera cam){
45         this.cam = cam;
46     }
47 
48     /**
49      * Calculates the distance from a spatial to the camera. Distance is a
50      * squared distance.
51      *
52      * @param spat
53      *            Spatial to distancize.
54      * @return Distance from Spatial to camera.
55      */
distanceToCam2(Geometry spat)56     private float distanceToCam2(Geometry spat){
57         if (spat == null)
58             return Float.NEGATIVE_INFINITY;
59 
60         if (spat.queueDistance != Float.NEGATIVE_INFINITY)
61             return spat.queueDistance;
62 
63         Vector3f camPosition = cam.getLocation();
64         Vector3f viewVector = cam.getDirection();
65         Vector3f spatPosition = null;
66 
67         if (spat.getWorldBound() != null){
68             spatPosition = spat.getWorldBound().getCenter();
69         }else{
70             spatPosition = spat.getWorldTranslation();
71         }
72 
73         spatPosition.subtract(camPosition, tempVec);
74         spat.queueDistance = tempVec.dot(tempVec);
75 
76         float retval = Math.abs(tempVec.dot(viewVector)
77                 / viewVector.dot(viewVector));
78         viewVector.mult(retval, tempVec);
79 
80         spat.queueDistance = tempVec.length();
81 
82         return spat.queueDistance;
83     }
84 
distanceToCam(Geometry spat)85     private float distanceToCam(Geometry spat){
86         // NOTE: It is best to check the distance
87         // to the bound's closest edge vs. the bound's center here.
88         return spat.getWorldBound().distanceToEdge(cam.getLocation());
89     }
90 
compare(Geometry o1, Geometry o2)91     public int compare(Geometry o1, Geometry o2) {
92         float d1 = distanceToCam(o1);
93         float d2 = distanceToCam(o2);
94 
95         if (d1 == d2)
96             return 0;
97         else if (d1 < d2)
98             return 1;
99         else
100             return -1;
101     }
102 }
103