/*
* Copyright (c) 2009-2012 jMonkeyEngine
* All rights reserved.
*
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* 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.
*
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* 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
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package com.jme3.terrain.geomipmap.lodcalc;
import com.jme3.export.JmeExporter;
import com.jme3.export.JmeImporter;
import com.jme3.math.FastMath;
import com.jme3.math.Vector3f;
import com.jme3.renderer.Camera;
import com.jme3.terrain.geomipmap.TerrainPatch;
import com.jme3.terrain.geomipmap.UpdatedTerrainPatch;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
public class PerspectiveLodCalculator implements LodCalculator {
private Camera cam;
private float pixelError;
private boolean turnOffLod = false;
public PerspectiveLodCalculator() {}
public PerspectiveLodCalculator(Camera cam, float pixelError) {
this.cam = cam;
this.pixelError = pixelError;
}
/**
* This computes the "C" value in the geomipmapping paper.
* See section "2.3.1.2 Pre-calculating d"
*
* @param cam
* @param pixelLimit
* @return
*/
private float getCameraConstant(Camera cam, float pixelLimit){
float n = cam.getFrustumNear();
float t = FastMath.abs(cam.getFrustumTop());
float A = n / t;
float v_res = cam.getHeight();
float T = (2f * pixelLimit) / v_res;
return A / T;
}
public boolean calculateLod(TerrainPatch patch, List<Vector3f> locations, HashMap<String, UpdatedTerrainPatch> updates) {
if (turnOffLod) {
// set to full detail
int prevLOD = patch.getLod();
UpdatedTerrainPatch utp = updates.get(patch.getName());
if (utp == null) {
utp = new UpdatedTerrainPatch(patch);
updates.put(utp.getName(), utp);
}
utp.setNewLod(0);
utp.setPreviousLod(prevLOD);
//utp.setReIndexNeeded(true);
return true;
}
float[] lodEntropies = patch.getLodEntropies();
float cameraConstant = getCameraConstant(cam, pixelError);
Vector3f patchPos = getCenterLocation(patch);
// vector from camera to patch
//Vector3f toPatchDir = locations.get(0).subtract(patchPos).normalizeLocal();
//float facing = cam.getDirection().dot(toPatchDir);
float distance = patchPos.distance(locations.get(0));
// go through each lod level to find the one we are in
for (int i = 0; i <= patch.getMaxLod(); i++) {
if (distance < lodEntropies[i] * cameraConstant || i == patch.getMaxLod()){
boolean reIndexNeeded = false;
if (i != patch.getLod()) {
reIndexNeeded = true;
// System.out.println("lod change: "+lod+" > "+i+" dist: "+distance);
}
int prevLOD = patch.getLod();
UpdatedTerrainPatch utp = updates.get(patch.getName());
if (utp == null) {
utp = new UpdatedTerrainPatch(patch);//save in here, do not update actual variables
updates.put(utp.getName(), utp);
}
utp.setNewLod(i);
utp.setPreviousLod(prevLOD);
//utp.setReIndexNeeded(reIndexNeeded);
return reIndexNeeded;
}
}
return false;
}
public Vector3f getCenterLocation(TerrainPatch patch) {
Vector3f loc = patch.getWorldTranslation().clone();
loc.x += patch.getSize() / 2;
loc.z += patch.getSize() / 2;
return loc;
}
@Override
public LodCalculator clone() {
try {
return (LodCalculator) super.clone();
} catch (CloneNotSupportedException ex) {
throw new AssertionError();
}
}
public void write(JmeExporter ex) throws IOException {
}
public void read(JmeImporter im) throws IOException {
}
public boolean usesVariableLod() {
return true;
}
public float getPixelError() {
return pixelError;
}
public void setPixelError(float pixelError) {
this.pixelError = pixelError;
}
public void setCam(Camera cam) {
this.cam = cam;
}
public void turnOffLod() {
turnOffLod = true;
}
public boolean isLodOff() {
return turnOffLod;
}
public void turnOnLod() {
turnOffLod = false;
}
}