Hi! I found this picture the other day and I thought it'd be nice to do some Processing applet similar to that. I defined a class for a grid of circles, and assigned a color, number, diameter and speed of rotation to each instance. The problem I find is that the colors do not blend as in the pic, as I thought they would by using the alpha function. Any ideas? Thanks! PD: I don't know if it's necessary, but I'll just leave the code here in case someone is interested.

1. // cmyk! (16/02/12)
   
   Malla[] capa;
   int lado = 400;
   int nc = 3;         // número de capas
   
   void setup() {
     size(600, 600);
     smooth();
     noStroke();
     capa = new Malla[nc];
     capa[0] = new Malla(6, 40, 5, 255, 255, 0);
     capa[1] = new Malla(6, 60, 3, 0, 255, 255);
     capa[2] = new Malla(6, 50, -2, 255, 0, 255);
   }
   
   void draw() {
     translate(300, 300);
     background(230);
     for (int i=0; i < capa.length; i++) {
       capa[i].paso();
     }
   }
   
   class Malla {
   
     int n, d, v, r, g, b;
     float angle = 0;
    
     Malla(int N, int D, int V, int R, int G, int B) {
       n = N; // número de círculos por lado
       d = D; // diámetro
       v = V; // velocidad
       r = R; // color en RGB
       g = G;
       b = B;
     }
      
     void paso() {
       angle += v*PI/1000;
       if (angle > TWO_PI) {angle -= TWO_PI; }
       fill(r, g, b, 140);
       float dl = lado/(n-1);
      
       pushMatrix();
       rotate(angle);
       for (int i=0; i<n; i++) {
         for (int j=0; j<n; j++) {
           ellipse(-lado/2 + i*dl, -lado/2 + j*dl, d, d);
         }
       }
       popMatrix();   
     } 
    
   }