Hello, everyone!

I am trying to adapt Mr. Shiffman's Simple Spring Example*
to store all my Vec2D's inside an ArrayList.

* http://www.shiffman.net/itp/classes/nature/toxiclibs_2010/simplespring/

As easy as pie… I guess.

However, my particles don´t stop when they reach the ground
like they should.

When I print my particle position, everything works fine until
it reaches thes maximum height. Here is a print…

{x:250.0, y:413.63782}
{x:250.0, y:433.8689}
{x:250.0, y:455.92014}
{x:250.0, y:479.8978}
{x:250.0, y:500.0}
{x:250.0, y:303.57776}
{x:250.0, y:103.50757}
{x:250.0, y:0.0}
{x:250.0, y:500.0}
{x:250.0, y:0.0}
{x:250.0, y:500.0}
{x:250.0, y:NaN}
{x:250.0, y:NaN}
{x:250.0, y:NaN}
{x:250.0, y:NaN}

NaN… so, I've found a way to transform a number into something else…nice…Nobel worthy…

Here's my code…

import toxi.physics2d.*;
import toxi.physics2d.behaviors.*;
import toxi.geom.*;

ArrayList allNodes;

VerletPhysics2D physics;

void setup(){
  frameRate(30);
  size(500,500);
  smooth();
  background(255);

  allNodes = new ArrayList();
  allNodes.add(new Particle(width/2,height/2));

  physics=new VerletPhysics2D();
  physics.addBehavior(new GravityBehavior(new Vec2D(0,0.001)));

  Vec2D center = new Vec2D(width/2,height/2);
  Vec2D extent = new Vec2D(width/2,height/2);
  physics.setWorldBounds(Rect.fromCenterExtent(center,extent));

}

void draw(){

  physics.update();

  background(255);

  for(int i=0; i<=allNodes.size()-1;i++){
    Particle thisParticle = (Particle)allNodes.get(i);
    physics.addParticle(thisParticle);
    thisParticle.display();
    if(mousePressed){
      if(dist(mouseX,mouseY,thisParticle.x,thisParticle.y)<=30){
        thisParticle.lock();
        thisParticle.x= mouseX;
        thisParticle.y= mouseY;
        thisParticle.unlock();
      }
    }
  }

  if(keyPressed) {
    if (key == '+' || key == '+') {
      allNodes.add(new Particle(random(width),random(height)));
      println("# NODES | "+allNodes.size());
    }
  }
}

class Particle extends VerletParticle2D {

  Particle(float x, float y) {
    super(x,y);
  }

  void display() {
    fill(255,100,100,100);
    noStroke();
    ellipse(x,y,30,30);
  }
}

Any help with this witchcraft dilemma would be much appreciated…
Thnaks for your time!