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/*
* 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
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.jme3.scene.control;
import com.jme3.bounding.BoundingVolume;
import com.jme3.export.InputCapsule;
import com.jme3.export.JmeExporter;
import com.jme3.export.JmeImporter;
import com.jme3.export.OutputCapsule;
import com.jme3.math.FastMath;
import com.jme3.renderer.Camera;
import com.jme3.renderer.RenderManager;
import com.jme3.renderer.ViewPort;
import com.jme3.scene.Geometry;
import com.jme3.scene.Mesh;
import com.jme3.scene.Spatial;
import java.io.IOException;
/**
* Determines what Level of Detail a spatial should be, based on how many pixels
* on the screen the spatial is taking up. The more pixels covered, the more detailed
* the spatial should be.
* It calculates the area of the screen that the spatial covers by using its bounding box.
* When initializing, it will ask the spatial for how many triangles it has for each LOD.
* It then uses that, along with the trisPerPixel value to determine what LOD it should be at.
* It requires the camera to do this.
* The controlRender method is called each frame and will update the spatial's LOD
* if the camera has moved by a specified amount.
*/
public class LodControl extends AbstractControl implements Cloneable {
private float trisPerPixel = 1f;
private float distTolerance = 1f;
private float lastDistance = 0f;
private int lastLevel = 0;
private int numLevels;
private int[] numTris;
/**
* Creates a new <code>LodControl</code>.
*/
public LodControl(){
}
/**
* Returns the distance tolerance for changing LOD.
*
* @return the distance tolerance for changing LOD.
*
* @see #setDistTolerance(float)
*/
public float getDistTolerance() {
return distTolerance;
}
/**
* Specifies the distance tolerance for changing the LOD level on the geometry.
* The LOD level will only get changed if the geometry has moved this
* distance beyond the current LOD level.
*
* @param distTolerance distance tolerance for changing LOD
*/
public void setDistTolerance(float distTolerance) {
this.distTolerance = distTolerance;
}
/**
* Returns the triangles per pixel value.
*
* @return the triangles per pixel value.
*
* @see #setTrisPerPixel(float)
*/
public float getTrisPerPixel() {
return trisPerPixel;
}
/**
* Sets the triangles per pixel value.
* The <code>LodControl</code> will use this value as an error metric
* to determine which LOD level to use based on the geometry's
* area on the screen.
*
* @param trisPerPixel triangles per pixel
*/
public void setTrisPerPixel(float trisPerPixel) {
this.trisPerPixel = trisPerPixel;
}
@Override
public void setSpatial(Spatial spatial){
if (!(spatial instanceof Geometry))
throw new IllegalArgumentException("LodControl can only be attached to Geometry!");
super.setSpatial(spatial);
Geometry geom = (Geometry) spatial;
Mesh mesh = geom.getMesh();
numLevels = mesh.getNumLodLevels();
numTris = new int[numLevels];
for (int i = numLevels - 1; i >= 0; i--)
numTris[i] = mesh.getTriangleCount(i);
}
public Control cloneForSpatial(Spatial spatial) {
try {
LodControl clone = (LodControl) super.clone();
clone.lastDistance = 0;
clone.lastLevel = 0;
clone.numTris = numTris != null ? numTris.clone() : null;
return clone;
} catch (CloneNotSupportedException ex) {
throw new AssertionError();
}
}
@Override
protected void controlUpdate(float tpf) {
}
protected void controlRender(RenderManager rm, ViewPort vp){
BoundingVolume bv = spatial.getWorldBound();
Camera cam = vp.getCamera();
float atanNH = FastMath.atan(cam.getFrustumNear() * cam.getFrustumTop());
float ratio = (FastMath.PI / (8f * atanNH));
float newDistance = bv.distanceTo(vp.getCamera().getLocation()) / ratio;
int level;
if (Math.abs(newDistance - lastDistance) <= distTolerance)
level = lastLevel; // we haven't moved relative to the model, send the old measurement back.
else if (lastDistance > newDistance && lastLevel == 0)
level = lastLevel; // we're already at the lowest setting and we just got closer to the model, no need to keep trying.
else if (lastDistance < newDistance && lastLevel == numLevels - 1)
level = lastLevel; // we're already at the highest setting and we just got further from the model, no need to keep trying.
else{
lastDistance = newDistance;
// estimate area of polygon via bounding volume
float area = AreaUtils.calcScreenArea(bv, lastDistance, cam.getWidth());
float trisToDraw = area * trisPerPixel;
level = numLevels - 1;
for (int i = numLevels; --i >= 0;){
if (trisToDraw - numTris[i] < 0){
break;
}
level = i;
}
lastLevel = level;
}
spatial.setLodLevel(level);
}
@Override
public void write(JmeExporter ex) throws IOException{
super.write(ex);
OutputCapsule oc = ex.getCapsule(this);
oc.write(trisPerPixel, "trisPerPixel", 1f);
oc.write(distTolerance, "distTolerance", 1f);
oc.write(numLevels, "numLevels", 0);
oc.write(numTris, "numTris", null);
}
@Override
public void read(JmeImporter im) throws IOException{
super.read(im);
InputCapsule ic = im.getCapsule(this);
trisPerPixel = ic.readFloat("trisPerPixel", 1f);
distTolerance = ic.readFloat("distTolerance", 1f);
numLevels = ic.readInt("numLevels", 0);
numTris = ic.readIntArray("numTris", null);
}
}
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