let frag, vert;

let sh, psh;

​

let fb;

​

let circleCount = 30;

​

let circleOffsets = [];

​

let curTime = 0;

let fps = 0;

​

let WEBGL_MODE;

​

function mod(a, b) {

  return (a % b + b) % b;

}

​

function preload() {

  frag = loadStrings('shader.frag');

  vert = loadStrings('shader.vert');

  pointFrag = loadStrings('point.frag');

  pointVert = loadStrings('point.vert');

  //result = loadStrings('/shader.frag');

}

​

function setup() {

  createCanvas(600, 600, WEBGL);

  background(0);

  noStroke();

  WEBGL_MODE = _renderer.drawingContext instanceof WebGLRenderingContext;

  fb = createGraphics(width, height, WEBGL);

  fb.noStroke();

  frag = frag.join('\n');

  vert = vert.join('\n');

  sh = fb.createShader(vert, frag);

  pointFrag = pointFrag.join('\n');

  pointVert = pointVert.join('\n');

  psh = createShader(pointVert, pointFrag);

  for (let i = 0; i < circleCount * circleCount; i++) {

    circleOffsets.push(createVector(random(0, 0), random(0, 0)));

  }

  fb.shader(sh);

}

​

function draw() {

  sh.setUniform('uResolution', width, height);

  sh.setUniform('uTime', millis() / 1000);

  sh.setUniform('uFrame', frameCount);

  fb.quad(-1, -1, 1, -1, 1, 1, -1, 1);

  //image(fb, -width/2, -height/2);

  fb.loadPixels();

  if (WEBGL_MODE)

    translate(-width/2, -height/2);

  image(fb, 0, 0);

  let pd = pixelDensity();

  shader(psh);

  //stroke(255, 120, 25);

  beginShape(POINTS);

  let r = width/circleCount*1.45;

  for (let x = 0; x < circleCount; x++) {

    for (let y = 0; y < circleCount; y++) { 

      let co = circleOffsets[x + y * circleCount];

      let xp = int((x + co.x) / (circleCount-1) * width);

      let yp = int((y + co.y) / (circleCount-1) * height);

      let f = fb.pixels[(xp + mod(height - yp*2, height) * width) * pd * 4];

      vertex(xp, yp);

      //strokeWeight(r * f / 255);

      //point(xp, yp);

    }

  }

  endShape();

  if (curTime > 1000) {

    print('FPS: ' + fps);

    curTime -= 1000;

    fps = 0;

  }

  curTime += deltaTime;

  fps++;

}