engine/src/core/com/jme3/renderer/queue/OpaqueComparator.java

/*
 * Copyright (c) 2009-2010 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 */

package com.jme3.renderer.queue;

import com.jme3.material.Material;
import com.jme3.math.Vector3f;
import com.jme3.renderer.Camera;
import com.jme3.scene.Geometry;

public class OpaqueComparator implements GeometryComparator {

    private Camera cam;
    private final Vector3f tempVec  = new Vector3f();
    private final Vector3f tempVec2 = new Vector3f();

    public void setCamera(Camera cam){
        this.cam = cam;
    }

    public float distanceToCam(Geometry spat){
        if (spat == null)
            return Float.NEGATIVE_INFINITY;
 
        if (spat.queueDistance != Float.NEGATIVE_INFINITY)
                return spat.queueDistance;
 
        Vector3f camPosition = cam.getLocation();
        Vector3f viewVector = cam.getDirection(tempVec2);
        Vector3f spatPosition = null;
 
        if (spat.getWorldBound() != null){
            spatPosition = spat.getWorldBound().getCenter();
        }else{
            spatPosition = spat.getWorldTranslation();
        }
 
        spatPosition.subtract(camPosition, tempVec);
        spat.queueDistance = tempVec.dot(viewVector);
 
        return spat.queueDistance;
    }

    public int compare(Geometry o1, Geometry o2) {
        Material m1 = o1.getMaterial();
        Material m2 = o2.getMaterial();

        int sortId = m1.compareTo(m2);

        if (sortId == 0){
            // use the same shader.
            // sort front-to-back then.
            float d1 = distanceToCam(o1);
            float d2 = distanceToCam(o2);

            if (d1 == d2)
                return 0;
            else if (d1 < d2)
                return -1;
            else
                return 1;
        }else{
            return sortId;
        }
    }

}