Processing 1.0 - Processing Discourse - voronoi from mesh library

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Index › Programming Questions & Help › Other Libraries › voronoi from mesh library

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voronoi from mesh library (Read 1683 times)

Robert

voronoi from mesh library
May 24^th, 2010, 7:39pm

I'm a bit confused, here. I'm working on a voronoi sketch. I've succeeded in adding new points and regenerating the voronoi, however, after adding several points I get an ArrayIndexOutOfBoundsException. I can continue to add points (it doesn't halt the sketch) but I can't figure what causes the exception, or how to fix it.

Exception in thread "AWT-EventQueue-0" java.lang.ArrayIndexOutOfBoundsException: 0
at megamu.mesh.IntArray.add(IntArray.java:22)
at megamu.mesh.Voronoi.<init>(Voronoi.java:127)
at MeshLibDemo_3.initMesh(MeshLibDemo_3.java:68)
at MeshLibDemo_3.mouseMoved(MeshLibDemo_3.java:95)
at processing.core.PApplet.handleMouseEvent(Unknown Source)
at processing.core.PApplet.checkMouseEvent(Unknown Source)
at processing.core.PApplet.mouseMoved(Unknown Source)
at java.awt.Component.processMouseMotionEvent(Component.java:6308)
at java.awt.Component.processEvent(Component.java:6032)
at java.awt.Container.processEvent(Container.java:2041)
at java.awt.Component.dispatchEventImpl(Component.java:4630)
at java.awt.Container.dispatchEventImpl(Container.java:2099)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269
)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174
)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

Quote:

import megamu.mesh.*;
Voronoi myVoronoi;
float[][] points;
float[][] myEdges;
MPolygon myRegions[],myHullRegion;
int col[];

float startX,startY,endX,endY;
float[][] regionCoordinates;

boolean showVoronoi=true;
boolean showDelaunay=false;
boolean showHull=false;

void setup() {
  size(500,250);
  // initialize points and calculate diagrams
  initMesh();
  smooth();
}
void draw() {
  background(200);
  if(myRegions==null) return;
if(showVoronoi) {
    strokeWeight(1);
    stroke(0);
     for(int i=0; i<myRegions.length; i++) {
      fill(col[i]); // use random color for each region

      regionCoordinates = myRegions[i].getCoords();
      myRegions[i].draw(this); // draw this shape

  }
noLoop();
}
}
void initMesh() {
  // is points array is null then initialize it
  if(points==null) initPoints();

  // save the current number of regions, so that
  // we can check if it's the same after the Voronoi
  // has been recalculated.
  int oldlength=0;
  if(myRegions!=null) oldlength=myRegions.length;

  myVoronoi = new Voronoi( points );
  myRegions = myVoronoi.getRegions();
  // if the number of regions is different than
  // before then recalculate the random colors
  if(oldlength!=myRegions.length) {
    col=new int[myRegions.length];
    for(int i=0; i<myRegions.length; i++) {
      float prob=random(100);
      if(prob>60) col[i]=color(random(30,100));
      else col[i]=color(random(200,255));
    }
    col[0]=color(255,0,0);
  }
}

void initPoints() {
    points = new float[(int)random(5,30)][2];
  for(int i=0; i<points.length; i++) {
    points[i][0] = random(width); // first point, x
    points[i][1] = random(height); // first point, y
  }
}
void mouseMoved() {
  // if myRegions is null then mesh is not ready
  if(myRegions==null) return;
  points[0][0]=mouseX;
  points[0][1]=mouseY;
  initMesh();
}
void mousePressed() {
     float[][] tmp = new float[1][2];
tmp[0][0]=mouseX;
  tmp[0][1]=mouseY;
  points = (float[][])concat( points, tmp );
  redraw();
}

martin_p

Re: voronoi from mesh library
Reply #1 - May 28^th, 2010, 7:09am

I personally don't like the processing array features (although they do implement stuff like array resizing that is readily available in ruby). So I have no experience of using them....
For a pragmatic solution try the following:-
Quote:

void mousePressed() {
  float[][] tmp = new float[1][2];
  tmp[0][0]=mouseX;
  tmp[0][1]=mouseY;
  points[0] = tmp[0];
  redraw();
}

I suspect that it is probably dodgy to resize arrays interfaced with external libraries (written in java). My solution seems to be more in line with Tom Cardens voronoicones example from processing hacks that your example reminds me of (worth a look if you haven't seen it).

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