Source Code:            Syntax: C#

// Distance 2D
// by REAS <http://reas.com>

// Move the mouse across the image to obscure and reveal the matrix. 
// Measures the distance from the mouse to each square and sets the
// iSize proportionally.

// Updated 21 August 2002

double max_distance;

public override void setup() {
  size(200, 200); 
  rectMode(CENTER);  
  noStroke();
  max_distance = dist(0, 0, width, height);
}

public override void draw() 
{
  background(51);

  for(int i=20; i<width; i+=20) {
    for(int j=20; j<width; j+=20) {
      double iSize = dist(mouseX, mouseY, i, j);
      iSize = iSize/max_distance * 66;
      rect(i, j, iSize, iSize);
    }
  }
}