This example is for Processing 3+. If you have a previous version, use the examples included with your software. If you see any errors or have suggestions, please let us know.

Milliseconds.

A millisecond is 1/1000 of a second. Processing keeps track of the number of milliseconds a program has run. By modifying this number with the modulo(%) operator, different patterns in time are created.

 
float scale;

void setup() {
  size(640, 360);
  noStroke();
  scale = width/20;
}

void draw() { 
  for (int i = 0; i < scale; i++) {
    colorMode(RGB, (i+1) * scale * 10);
    fill(millis()%((i+1) * scale * 10));
    rect(i*scale, 0, scale, height);
  }
}