This sample shows a cross with a square in the middle.
The cross is built with two big lines that are placed in the middle of the pictures above them is a medium-sized square. If you look into the middle of the picture the black corners begin to move they get bigger. Through the contrast of black and white it is static and dynamic at the same time.
function setup() {
var a = 150;
var canvas = createCanvas(500, 500);
canvas.parent('sketch');
background(255);
fill(0);
rect(350, 0, a, a);
rect(350, 350, a, a);
rect(0, 0, a, a);
rect(0, 350, a, a);
}
function draw() {
fill(255, 255, 255);
rectMode(CENTER);
noStroke();
rect(width / 2, height / 2, 300, 300);
}