/*
* Copyright (c) 2009-2012 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
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*/
package com.jme3.shadow;
import com.jme3.bounding.BoundingBox;
import com.jme3.math.FastMath;
import com.jme3.math.Matrix4f;
import com.jme3.renderer.Camera;
import com.jme3.renderer.queue.GeometryList;
import static java.lang.Math.max;
import static java.lang.Math.min;
/**
* Includes various useful shadow mapping functions.
*
* @see
* <ul>
* <li><a href="http://appsrv.cse.cuhk.edu.hk/~fzhang/pssm_vrcia/">http://appsrv.cse.cuhk.edu.hk/~fzhang/pssm_vrcia/</a></li>
* <li><a href="http://http.developer.nvidia.com/GPUGems3/gpugems3_ch10.html">http://http.developer.nvidia.com/GPUGems3/gpugems3_ch10.html</a></li>
* </ul>
* for more info.
*/
public final class PssmShadowUtil {
/**
* Updates the frustum splits stores in <code>splits</code> using PSSM.
*/
public static void updateFrustumSplits(float[] splits, float near, float far, float lambda) {
for (int i = 0; i < splits.length; i++) {
float IDM = i / (float) splits.length;
float log = near * FastMath.pow((far / near), IDM);
float uniform = near + (far - near) * IDM;
splits[i] = log * lambda + uniform * (1.0f - lambda);
}
// This is used to improve the correctness of the calculations. Our main near- and farplane
// of the camera always stay the same, no matter what happens.
splits[0] = near;
splits[splits.length - 1] = far;
}
/**
* Compute the Zfar in the model vieuw to adjust the Zfar distance for the splits calculation
*/
public static float computeZFar(GeometryList occ, GeometryList recv, Camera cam) {
Matrix4f mat = cam.getViewMatrix();
BoundingBox bbOcc = ShadowUtil.computeUnionBound(occ, mat);
BoundingBox bbRecv = ShadowUtil.computeUnionBound(recv, mat);
return min(max(bbOcc.getZExtent() - bbOcc.getCenter().z, bbRecv.getZExtent() - bbRecv.getCenter().z), cam.getFrustumFar());
}
}