This is a processing sketch that draws sets of circles and moves other sets across the screen. It uses a couple funtions.

Function Example 20120221.pde

// this draws sets of circles in rows on the screen
// Steve Lambert February 14, 2012

// variables

  int stage = 1;
  float cDim = 15; // dimensions of the circle
  float y = 0 - cDim; // y is the starting position of the row
  float xSpacing = cDim; // spacing between the circles
  float ySpacing = 10; // spacing below each row
  float x = 0; // x is position of the circle
  color onColor = color(255,255,0);
  color offColor = color(0,0,0);
  float ch1Reset = cDim * 0; // where channel 1 starts again
  float ch2Reset = cDim * 1; // ''
  float ch3Reset = cDim * 2; // ''
  float ch4Reset = cDim * 3; // ''

void setup() {
  size(1280, 700);
  background(125);
  ellipseMode(CORNER);
  noStroke();
  smooth();
}

  int w=0;
void draw() {

//if (stage == 1) {   // if the stage is 1, do the beginning.
  background(175);
  drawBlack();
  flash(w); 
  delay(250);
  w += 1;
  if (w >3) {
    w=0;
  }


 
 
// end
}

void flash(float chReset) {
  while (y <= height){ 

  while (x <= width) {
    fill(onColor);
    ellipse(x,y,cDim,cDim);
    x = x + xSpacing*4;
    } // end x loop
  y = y + cDim + ySpacing; // this starts a new row
  x = cDim * chReset; // this resets the x postions - can use chXReset

 } // end y loop
// stage = 2;
 x=0;
 y = 0 - cDim;
//  draw();
}



// DRAWBLACK CIRCLES

void drawBlack() {
  // draws all 4 off
 while (y <= height){ 

  while (x <= width) {
    fill(offColor);
    ellipse(x,y,cDim,cDim);
    x = x + xSpacing;
    } // end x loop

  y = y + cDim + ySpacing; // this starts a new row
  x = 0; // this resets the x postions
  
 } // end y loop
 x=0;
 y=0-cDim;
} // end drawBlack