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
33package com.jme3.renderer.queue;
34
35import com.jme3.math.Vector3f;
36import com.jme3.renderer.Camera;
37import com.jme3.scene.Geometry;
38
39public class TransparentComparator implements GeometryComparator {
40
41    private Camera cam;
42    private final Vector3f tempVec = new Vector3f();
43
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     */
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
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
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