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 33 package com.jme3.scene.control; 34 35 import com.jme3.bounding.BoundingBox; 36 import com.jme3.bounding.BoundingSphere; 37 import com.jme3.bounding.BoundingVolume; 38 import com.jme3.math.FastMath; 39 40 /** 41 * <code>AreaUtils</code> is used to calculate the area of various objects, such as bounding volumes. These 42 * functions are very loose approximations. 43 * @author Joshua Slack 44 * @version $Id: AreaUtils.java 4131 2009-03-19 20:15:28Z blaine.dev $ 45 */ 46 47 public class AreaUtils { 48 49 /** 50 * calcScreenArea -- in Pixels 51 * Aproximates the screen area of a bounding volume. If the volume isn't a 52 * BoundingSphere, BoundingBox, or OrientedBoundingBox 0 is returned. 53 * 54 * @param bound The bounds to calculate the volume from. 55 * @param distance The distance from camera to object. 56 * @param screenWidth The width of the screen. 57 * @return The area in pixels on the screen of the bounding volume. 58 */ calcScreenArea(BoundingVolume bound, float distance, float screenWidth)59 public static float calcScreenArea(BoundingVolume bound, float distance, float screenWidth) { 60 if (bound.getType() == BoundingVolume.Type.Sphere){ 61 return calcScreenArea((BoundingSphere) bound, distance, screenWidth); 62 }else if (bound.getType() == BoundingVolume.Type.AABB){ 63 return calcScreenArea((BoundingBox) bound, distance, screenWidth); 64 } 65 return 0.0f; 66 } 67 calcScreenArea(BoundingSphere bound, float distance, float screenWidth)68 private static float calcScreenArea(BoundingSphere bound, float distance, float screenWidth) { 69 // Where is the center point and a radius point that lies in a plan parallel to the view plane? 70 // // Calc radius based on these two points and plug into circle area formula. 71 // Vector2f centerSP = null; 72 // Vector2f outerSP = null; 73 // float radiusSq = centerSP.subtract(outerSP).lengthSquared(); 74 float radius = (bound.getRadius() * screenWidth) / (distance * 2); 75 return radius * radius * FastMath.PI; 76 } 77 calcScreenArea(BoundingBox bound, float distance, float screenWidth)78 private static float calcScreenArea(BoundingBox bound, float distance, float screenWidth) { 79 // Calc as if we are a BoundingSphere for now... 80 float radiusSquare = bound.getXExtent() * bound.getXExtent() 81 + bound.getYExtent() * bound.getYExtent() 82 + bound.getZExtent() * bound.getZExtent(); 83 return ((radiusSquare * screenWidth * screenWidth) / (distance * distance * 4)) * FastMath.PI; 84 } 85 }