let gfx, gfx2;

let frag1, frag2;

const DIM = 800.0;

const RDIM = 2;

const NUM = 25500;

​

let stepper_src = `

precision mediump float;

uniform sampler2D tex0;//previousState;

uniform float DIM;

uniform vec2 mouse;

​

int wasAlive(vec2 coord) {

  if (coord.x < 0.0 || DIM < coord.x || coord.y < 0.0 || DIM < coord.y) return 0;

  vec4 px = texture2D(tex0, coord/DIM);

  return px.r < 0.1 ? 1 : 0;

}

void main(void) {

  vec2 coord = vec2(gl_FragCoord);

  int aliveNeighbors =

    wasAlive(coord+vec2(-1.,-1.)) +

    wasAlive(coord+vec2(-1.,0.)) +

    wasAlive(coord+vec2(-1.,1.)) +

    wasAlive(coord+vec2(0.,-1.)) +

    wasAlive(coord+vec2(0.,1.)) +

    wasAlive(coord+vec2(1.,-1.)) +

    wasAlive(coord+vec2(1.,0.)) +

    wasAlive(coord+vec2(1.,1.));

  bool nowAlive = wasAlive(coord) == 1 ? 2 <= aliveNeighbors && aliveNeighbors <= 3 : 3 == aliveNeighbors;

  gl_FragColor = nowAlive ? vec4(0.,0.,0.,1.) : vec4(1.,1.,1.,1.);

}`;

​

let sand_src = `

precision mediump float;

uniform sampler2D tex0;//previousState;

uniform float DIM;

uniform vec2 mouse;

​

int wasAlive(vec2 coord) {

  if (coord.x < 0.0 || DIM < coord.x || coord.y < 0.0 || DIM < coord.y) return 0;

  vec4 px = texture2D(tex0, coord/DIM);

  return px.r < 0.1 ? 1 : 0;

}

​

void main(void) {

  vec2 coord = vec2(gl_FragCoord);

​

  bool nowAlive = false;

  if (wasAlive(coord+vec2(0.,-1.))==1) {

    nowAlive = true;

  }

​

  // if (wasAlive(coord+vec2(0.,-1.)) {

  //   nowAlive = true;

  //   // coord+vec2(0.,-1.) = 0.;

  // }

  //bool nowAlive = wasAlive(coord) == 1 ? 2 <= aliveNeighbors && aliveNeighbors <= 3 : 3 == aliveNeighbors;

  gl_FragColor = nowAlive ? vec4(0.,0.,0.,1.) : vec4(1.,1.,1.,1.);

}`;

​

// not needed with p5

let render_src = `precision mediump float;

uniform sampler2D state;

void main(void) {

  vec2 coord = vec2(gl_FragCoord)/400.0;

  gl_FragColor = texture2D(state, coord);

}`;

​

let nextStateIndex = 0;

​

let gfxs, frags;

function setup() {

  createCanvas(DIM, DIM);

  // createARCanvas(DIM,DIM);

  pixelDensity(1);

  gfx = createGraphics(width, height);

  gfx2 = createGraphics(width, height);

​

  gfx.background(220);

  gfx2.background(220);

​

  gfx.rectMode(CENTER);

  gfx2.rectMode(CENTER);

  gfx.stroke(0);

  gfx2.stroke(0);

  gfx.fill(0);

  gfx2.fill(0);

  for (let _ = 0; _ < NUM; _++) {

    let x = random(width - 1);

    let y = random(height - 1);

    gfx.rect(x, y, RDIM,RDIM);

    gfx2.rect(x, y, RDIM,RDIM);

  }

​

  frag1 = gfx.createFilterShader(stepper_src);

  frag2 = gfx2.createFilterShader(stepper_src);

  // frag1 = gfx.createFilterShader(sand_src);

  // frag2 = gfx2.createFilterShader(sand_src);

​

  gfxs = [gfx, gfx2];

  frags = [frag1, frag2];

  // saveGif("ca.gif", 5);

}

​

function draw() {

  let prevStateIndex = 1 - nextStateIndex;

​

  frags[nextStateIndex].setUniform('DIM', DIM);

  frags[nextStateIndex].setUniform('mouse', [mouseX, mouseY]);

  gfxs[nextStateIndex].filter(frags[nextStateIndex]);

  image(gfxs[nextStateIndex], 0, 0);

​

  nextStateIndex = prevStateIndex;

}

​

function mousePressed() {

}