function preload() {

  // load the shader definitions from files

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

}

function setup() {

  createCanvas(300, 300, WEBGL);

  // use the shader

  shader(lineShader);

  stroke(0);

  strokeWeight(3);

  // lineShader.setUniform('p', [-0.74364388703, 0.13182590421]);

  describe('');

}

​

function draw() {

  for(let y = 0; y < height; y+=10) {

    for(let x = 0; x < width; x+=10) {

      line(x, 0, x, height);

      line(0, y, width, y);

    }

  }

}