let glitchShader;

​

function preload() {

  glitchShader = loadShader('shader.vert', 'shader.frag');

}

​

function setup() {

  createCanvas(600, 600, WEBGL);

  screen = createGraphics(width, height);

  screen.background(50);

  screen.stroke(255);

  screen.strokeWeight(5);

​

  shader(glitchShader);

}

​

​

​

function draw() {

  if(mouseIsPressed) {

    screen.line(mouseX, mouseY, pmouseX, pmouseY);

  }

  drawScreen();

}

​

​

function drawScreen() {

  glitchShader.setUniform('texture', screen);

  glitchShader.setUniform('noise', getNoiseValue());

  rect(-width/2, -height/2, width, height);

}

​

function getNoiseValue() { 

  let v = noise(millis()/100);

  const cutOff = 0.5;

  if(v < cutOff) {

    return 0;

  }

  v = pow((v-cutOff) * 1/(1-cutOff), 2);

  return v;

}

​