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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.shadow;
     33 
     34 import com.jme3.bounding.BoundingBox;
     35 import com.jme3.math.FastMath;
     36 import com.jme3.math.Matrix4f;
     37 import com.jme3.renderer.Camera;
     38 import com.jme3.renderer.queue.GeometryList;
     39 import static java.lang.Math.max;
     40 import static java.lang.Math.min;
     41 
     42 /**
     43  * Includes various useful shadow mapping functions.
     44  *
     45  * @see
     46  * <ul>
     47  * <li><a href="http://appsrv.cse.cuhk.edu.hk/~fzhang/pssm_vrcia/">http://appsrv.cse.cuhk.edu.hk/~fzhang/pssm_vrcia/</a></li>
     48  * <li><a href="http://http.developer.nvidia.com/GPUGems3/gpugems3_ch10.html">http://http.developer.nvidia.com/GPUGems3/gpugems3_ch10.html</a></li>
     49  * </ul>
     50  * for more info.
     51  */
     52 public final class PssmShadowUtil {
     53 
     54     /**
     55      * Updates the frustum splits stores in <code>splits</code> using PSSM.
     56      */
     57     public static void updateFrustumSplits(float[] splits, float near, float far, float lambda) {
     58         for (int i = 0; i < splits.length; i++) {
     59             float IDM = i / (float) splits.length;
     60             float log = near * FastMath.pow((far / near), IDM);
     61             float uniform = near + (far - near) * IDM;
     62             splits[i] = log * lambda + uniform * (1.0f - lambda);
     63         }
     64 
     65         // This is used to improve the correctness of the calculations. Our main near- and farplane
     66         // of the camera always stay the same, no matter what happens.
     67         splits[0] = near;
     68         splits[splits.length - 1] = far;
     69     }
     70 
     71     /**
     72      * Compute the Zfar in the model vieuw to adjust the Zfar distance for the splits calculation
     73      */
     74     public static float computeZFar(GeometryList occ, GeometryList recv, Camera cam) {
     75         Matrix4f mat = cam.getViewMatrix();
     76         BoundingBox bbOcc = ShadowUtil.computeUnionBound(occ, mat);
     77         BoundingBox bbRecv = ShadowUtil.computeUnionBound(recv, mat);
     78 
     79         return min(max(bbOcc.getZExtent() - bbOcc.getCenter().z, bbRecv.getZExtent() - bbRecv.getCenter().z), cam.getFrustumFar());
     80     }
     81 }
     82