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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.BoundingBox;
import com.jme3.bounding.BoundingSphere;
import com.jme3.bounding.BoundingVolume;
import com.jme3.math.FastMath;
/**
* <code>AreaUtils</code> is used to calculate the area of various objects, such as bounding volumes. These
* functions are very loose approximations.
* @author Joshua Slack
* @version $Id: AreaUtils.java 4131 2009-03-19 20:15:28Z blaine.dev $
*/
public class AreaUtils {
/**
* calcScreenArea -- in Pixels
* Aproximates the screen area of a bounding volume. If the volume isn't a
* BoundingSphere, BoundingBox, or OrientedBoundingBox 0 is returned.
*
* @param bound The bounds to calculate the volume from.
* @param distance The distance from camera to object.
* @param screenWidth The width of the screen.
* @return The area in pixels on the screen of the bounding volume.
*/
public static float calcScreenArea(BoundingVolume bound, float distance, float screenWidth) {
if (bound.getType() == BoundingVolume.Type.Sphere){
return calcScreenArea((BoundingSphere) bound, distance, screenWidth);
}else if (bound.getType() == BoundingVolume.Type.AABB){
return calcScreenArea((BoundingBox) bound, distance, screenWidth);
}
return 0.0f;
}
private static float calcScreenArea(BoundingSphere bound, float distance, float screenWidth) {
// Where is the center point and a radius point that lies in a plan parallel to the view plane?
// // Calc radius based on these two points and plug into circle area formula.
// Vector2f centerSP = null;
// Vector2f outerSP = null;
// float radiusSq = centerSP.subtract(outerSP).lengthSquared();
float radius = (bound.getRadius() * screenWidth) / (distance * 2);
return radius * radius * FastMath.PI;
}
private static float calcScreenArea(BoundingBox bound, float distance, float screenWidth) {
// Calc as if we are a BoundingSphere for now...
float radiusSquare = bound.getXExtent() * bound.getXExtent()
+ bound.getYExtent() * bound.getYExtent()
+ bound.getZExtent() * bound.getZExtent();
return ((radiusSquare * screenWidth * screenWidth) / (distance * distance * 4)) * FastMath.PI;
}
}
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