​

let prevFrame;

​

function preload() {

  golShader = loadShader('gol.vert', 'gol.frag');

}

​

function setup() {

  createCanvas(600, 600, WEBGL);

  pixelDensity(1);

  noSmooth();

  prevFrame = createGraphics(width, height);

  prevFrame.pixelDensity(1);

  prevFrame.noSmooth();

  background(0);

  stroke(255);

  shader(golShader);

  golShader.setUniform("normalRes", [1.0/width, 1.0/height]);

}

​

function draw() {

  if(mouseIsPressed) {

    line(

      pmouseX-width/2,

      pmouseY-height/2,

      mouseX-width/2,

      mouseY-height/2

    );

  }  

  // Copy the rendered image into our prevFrame image

  prevFrame.image(get(), 0, 0);  

  // Set the image of the previous frame into our shader

  golShader.setUniform('tex', prevFrame);

  // Give the shader a surface to draw on

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

}