I've now figured that I have to load the file using XMLElement and can just modify the "d" attribute. My next task to to randomise the values in that attribute. I've reworked some example code to display the values of the d attribute:

1. void setup() {
     XMLElement xml = new XMLElement(this, "file.svg");
     printd(xml);
   }
   
   void printd(XMLElement xml) {
     int numSites = xml.getChildCount();
     for (int i = 0; i < numSites; i++) {
       XMLElement kid = xml.getChild(i);
       String id = kid.getStringAttribute("d");
       if(id != null){
         println(id);
       }   
       printd(kid);
     }
   }

So, how would I now change those values in "id"? I'm used to using sed on Linux for these sort of find/replace tasks, but can't find how to do it in Processing.

maybe you can use geomerative library to use a PShape and get the points to manipulate them.

http://www.ricardmarxer.com/geomerative/

Thanks, will give it a try.

A potential problem I can see is that Processing seems to be very picky about what svg files it can load. I use Inkscape to make my svg files and so far it, using PShape, I haven't been able to load any of my Inkscape artworks. Reading the file via XMLElement has worked well so far

Thanks for the tip on using geomerative, it's very handy. I've alreayd managed to create this, which uses the polygoniser feature: http://is.gd/dpfDk. I've modified some of the example code and foudn a way to load the points and then randomise their placement, but I'm still having a fwe problems. See the code below

1. import processing.opengl.*;
   import processing.xml.*;
   import geomerative.*;
   
   RShape shp;
   RShape polyshp;
   
   void setup(){
     size(600, 600, P3D);
     colorMode(RGB, 255);
     frameRate(24);
   
     // VERY IMPORTANT: Allways initialize the library before using it
     RG.init(this);
   
     shp = RG.loadShape("penguin.svg");
   }
   
   void draw(){
     background(146,255,75);
   
     polyshp = RG.polygonize(shp);
   
     // We draw the polygonized group with the SVG styles
     RG.shape(polyshp);
    
       RPoint[] pnts = shp.getPoints();
   
       for ( int i = 1; i < pnts.length; i++ )
       {
           line( pnts[i-1].x*random(2), pnts[i-1].y*random(2), pnts[i].x*random(2), pnts[i].y*random(2) );
       }
   }

The problem I'm having is that this method just redraws the shape. Is there anyway to actually modify the node handles in the shape itself?