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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 
     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