// from http://processing.org/discourse/yabb_beta/YaBB.cgi?board=Exhibition;action=display;num=1203259632
// cDotLinesBounce2_lincol (2008-mar-31)
// pierrecharland@hotmail.com

int modul = 5;
int count = (20/modul)*modul;
int pulsefac = 1000;//from 64 to 30000
Ball balls[] = new Ball[count];
color dotFillC = color(0,40);
color dotStrokeC = color(25,50,155,80);
color lineStrokeC = color(0, 20);
float RR,GG,BB,dR,dG,dB;
float radius;

void setup() {
  size(800, 800);
  radius = width/2.2;
  background(255);
  smooth();
  float vr = TWO_PI/count;
  float a, rx0, ry0, rx1, ry1;
  for (int i=0; i<count; i++) {
    a = i*vr;
    //rx0 = cos(a) * radius;
    //ry0 = sin(a) * radius;
    //rx0 = cos(a) * radius * (1 + (modul-(i%modul))/(float)modul);
    //ry0 = sin(a) * radius * (1 + (modul-(i%modul))/(float)modul);
    rx0 = cos(a) * radius * (1 + (i%modul)/(float)modul);
    ry0 = sin(a) * radius * (1 + (i%modul)/(float)modul);
    rx1 = cos(a) * radius * (i%modul)/(float)modul;
    ry1 = sin(a) * radius * (i%modul)/(float)modul;
    balls[i] = new Ball(rx0, ry0, rx1 ,ry1, 1, i);
  }
  dR=1.0;
  dG=1.9;
  dB=2.8;
}//setup()

void draw() {
  //background(255);
  for (int i=0; i<balls.length; i++) {
    balls[i].pulse();
    balls[i].move();
  }
  for (int i=0; i<balls.length; i++) {
    // balls[i].drawdots();
  }
  for (int i=0; i<balls.length; i+=3) {
    balls[i].drawlines();
  }
  RR+=dR;
  GG+=dG;
  BB+=dB;
  if (RR<0 || RR>255) {
    dR*=-1;
    RR=(RR+dR);
  }
  if (GG<0 || GG>255) {
    dG*=-1;
    GG=(GG+dG);
  }
  if (BB<0 || BB>255) {
    dB*=-1;
    BB=(BB+dB);
  }
}//draw()

class Ball {
  float rx0, ry0, rx1, ry1, rx, ry, s, vx, vy, x, y, t;
  int id;
  Ball(float rx0_, float ry0_, float rx1_, float ry1_, float s_, int id_) {
    rx0 = rx0_;
    ry0 = ry0_;
    rx1 = rx1_;
    ry1 = ry1_;
    rx = rx0;
    ry = ry0;
    x = (width-radius)/2 + rx;
    y = (height-radius)/2 + ry;
    s = s_;
    id = id_;
    vx = 4;
    vy = 4;
    t = 0;
  }
  void pulse() {
    x-=rx;
    y-=ry;
    t += TWO_PI/pulsefac;
    rx = rx0 + (sin(t)) * (rx1-rx0);
    ry = ry0 + (sin(t)) * (ry1-ry0);
    x+=rx;
    y+=ry;
  }
  void move() {
    if (x < s/2) {
	x = s/2 + 1;
	vx *= -1;
    } 
    else if (x > width-s/2) {
	x = width-s/2-1;
	vx *= -1;
    }
    if (y < s/2) {
	y = s/2 + 1;
	vy *= -1;
    } 
    else if (y > height-s/2) {
	y = height-s/2-1;
	vy *= -1;
    }
    x += vx;
    y += vy;
  }
  void drawdots() {
    fill(dotFillC);
    stroke(dotStrokeC);
    ellipse(x, y, s, s);
  }
  void drawlines() {
    float lenRatio;
    for (int i=id+1; i<balls.length; i+=3) {
	//choose 1 of 2 lenRatio:
	//lenRatio=(sqrt(sq(balls[i].x-x)+sq(balls[i].y-y))/(1.3*width));
	lenRatio=(abs(balls[i].x-x)+abs(balls[i].y-y))/(1.7*width);
	//choose 1 of 2 stroke:
	stroke(RR,GG,BB,lenRatio*255);
	//stroke(RR,GG,BB,(1.0-lenRatio)*255);
	line(x, y, balls[i].x, balls[i].y);
    }
  }
}//Ball class