VisClient/org/hfbk/vis/visnode/VisKeycloud.java

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/*
 * Created on 27.04.2008
 */
package org.hfbk.vis.visnode;

import org.dronus.graph.Node;
import org.lwjgl.util.vector.Vector3f;

public class VisKeycloud extends VisNode {

        final float RADIUSFACTOR=15;
        
        public VisKeycloud(Node node, Vector3f position) {
                super(node, position);
        }
        
        
        void renderSelf() {
                if (layoutLocked) return;
                
                /*
                 * we now try to space the keywords regulary on a sphere.
                 * therefore we assume the sphere surface as a 2d plane
                 * and place the keywords approx equidistant in it. as
                 * the plane is spherical bend, this don't result in a regular 
                 * grid. we prior the lattitudes so they get a truly equidistant
                 * spacing and fill them with a longitudal grid til circle 
                 * completes. By carefully adjusting the sphere radius we
                 * make sure all keywords find theire place.  
                 */
                
                int n=children.size();
                
                //compute the distance of keywords on the 2d surface of the 3d sphere
                double dist=Math.PI*2/(Math.floor(Math.sqrt(n*4))+1);
                
                //compute needed radius for sphere
                radius=RADIUSFACTOR*(float)Math.sqrt(n/4/Math.PI);

                int i=0;
                for (double lat=dist/2-Math.PI/2; lat<Math.PI/2 && i<n; lat+=dist) //lattitudal grid
                        for (double lon=dist/2; lon<Math.PI*2 && i<n; lon+=dist/(1-Math.abs(lat/Math.PI*2))){ //longitudal grid 
                                
                                children.get(i).position=new Vector3f(
                                                (float)(radius*Math.cos(lat)*Math.cos(lon)),
                                                (float)(radius*-Math.sin(lat)),
                                                (float)(radius*Math.cos(lat)*-Math.sin(lon))
                                );
                                i++;
                        }
                
                layoutLocked=true;
        }

}

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