De Computer Graphics and Art vol3 n°2 page 20, par Reiner Schneeberger and students

// This sketch is part of the ReCode Project - http://recodeproject.com
// From Computer Graphics and Art vol3 no2 pg 22
// by Reiner Schneeberger
// 
// Untitled #5 is part of a 10 piece series, intended to test viewers
// perception of art and composition. The section is titled "Experimental
// Esthetics with Computer Graphics -- Analyses of Viewers Impressions 
// of Computer Graphics."
// 
// Jonathan Bobrow
// 2012
// Creative Commons license CC BY-SA 3.0
//
// note: .f enforces float division, dividing by an int would automatically round down
// i.e. 1/2 = 0 , 1/2.f = .5

var gridSize = 40;
var density = 10;

function setup(){
 createCanvas(780, 780);
 background(255);
 
 stroke(0);
 strokeWeight(1);
 var padding = gridSize/density; // even spacing for lines
 
 var rows = height/gridSize;
 var cols = width/gridSize;
 
 for(var i = 0; i < rows; i++){ // iterate over the # of rows (top to bottom)
 for(var j = 0; j < cols; j++){ // iterate over the # of columns (left to right)
 
 push();
 translate(j*gridSize, i*gridSize); // move to grid location
 translate(gridSize/2, gridSize/2); // move to rotate around center
 if(random(1) < .5) 
 rotate(PI/2); // rotate vertical or horizontal
 else 
 rotate(PI);
 
 for(var k = 0; k < density; k++){ // draw # of lines based on density with even spacing
 var _x = (k - density/2) * padding; 
 line(_x, -gridSize/2, _x, gridSize/2);
 }
 pop();
 }
 }
}