VisClient/org/hfbk/vis/VisNodeLayouter.java

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package org.hfbk.vis;


import java.util.List;

import org.hfbk.vis.visnode.VisNode;
import org.lwjgl.util.vector.Vector3f;

public class VisNodeLayouter {


        public static void layOut(VisNode node, float spreadX, float spreadY, float spreadZ){
                List<VisNode> childs=node.children;
                int n=childs.size();
                
                if (node.layoutLocked || childs.size()==0) //we have finished this in the past
                        return; 
                //we need to buffer the new positions 
                //else the partially updated nodes affects the ones still to update 
                Vector3f[] updatePos=new Vector3f[n];

                for (int i=0; i<n; i++) //fill with cloned positions
                        updatePos[i]=new Vector3f(childs.get(i).position);
                
                //repelling force between node pairs
                for (int i=0; i<n; i++){
                        VisNode ni=childs.get(i);
                        for (int j=i+1; j<n; j++){ //every pair is only considered once
                                VisNode nj=childs.get(j);
                                Vector3f diff=Vector3f.sub(ni.position,nj.position,null);
                                
                                float r=diff.lengthSquared();
                                diff.scale(2f/r);
                                diff.x*=spreadX; diff.y*=spreadY; diff.z*=spreadZ;
                                
                                Vector3f.add(updatePos[i], diff, updatePos[i]);
                                Vector3f.sub(updatePos[j], diff, updatePos[j]);
                        }
                }
                
                //attracting force to parent node
                for (int i=0; i<updatePos.length; i++){                                         
                        VisNode ni=childs.get(i);
                        
                        updatePos[i].scale(.95f); //attract
                        
                        //float d=updatePos[i].length()/10;
                        //updatePos[i].scale(1/d);  //repell if too near
                        
                        node.layoutLocked=true; //if we move nothing, we are finished forever.                  
                        //we do some stickyness so the nodes will not creep forever but settle down
                        float speed=Vector3f.sub(updatePos[i], childs.get(i).position,null).length();
                        if (speed >.1f) {//if fast enough update the node.
                                ni.position=updatePos[i];
                                node.layoutLocked=false; //we still need to layout
                        }
                        
                }
        }               
        
}

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