(t,i,x,y) => <dat.gui>

​

let tixy = function(t, i, x, y) { return 0; }

let obj = {

  "(t,i,x,y) =>": 'sin(t-sqrt((x-7.5)**2+(y-6)**2))'

}

​

function tryMakeTixy() {

  let newTixy = eval('let it = function (t,i,x,y){ return '+obj['(t,i,x,y) =>']+'; }; it');

  if (typeof(newTixy) === "function") {

    tixy = newTixy;

    startMillis = millis();

  }

}

​

function preload() {

  let gui = new dat.gui.GUI({width: 360});

  //gui.remember(obj);

  gui.add(obj, '(t,i,x,y) =>').onChange(tryMakeTixy);

}

let startMillis = 0;

function setup() {

  createCanvas(windowWidth, windowHeight);

  noStroke();

  tryMakeTixy();

}

​

function draw() {

  background(0);

  let maxDim = min(windowWidth, windowHeight) / 2.0;

  let windowCenterX = windowWidth / 2.0;

  let windowCenterY = windowHeight / 2.0;

  let t = (millis()-startMillis)/1000.0;

  for (var i = 0; i < 256; i++) {

    let x = int(i % 16);

    let y = int(i / 16);

    let value = tixy(t, i, x, y);

    if (value<0) fill(color(265, 62, 75));

    else fill(color(255));

    let size = map(abs(value), 0.0, 1.0, 0.0, maxDim/8.0, true); 

    ellipse(map(x, -0.5, 15.5, windowCenterX-maxDim, windowCenterX+maxDim),

            map(y, -0.5, 15.5, windowCenterY-maxDim, windowCenterY+maxDim), size, size);

  }

}