let flowfield;

​

let cellSize = 20;

let minDist = cellSize / 2;

​

let noiseScale = .1;

let radius = 3;

let speed = minDist;

​

let s;

​

let distCells;

let dw, dh;

​

function smoothstep(edge0, edge1, x) {

  if (x < 0)

    return edge0;

  if (x > 1)

    return edge1;

  return lerp(edge0, edge1, x * x * (3 - 2 * x));

}

​

function mod(a, b) {

  return a - b*floor(a/b);

}

​

function setup() {

  createCanvas(600, 600);

  background(125);

  //noStroke();

  flowfield = new Flowfield(width / cellSize, height / cellSize);

  dw = ceil(width / minDist);

  dh = ceil(height / minDist);

  distCells = new Array(dw * dh);

  for (let i = 0; i < distCells.length; i++) {

    distCells[i] = [];

  }

  s = new Streamline(width/2, height/2);

  let d = cellSize / speed * 0.6;

  stroke(0);

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

    for (let y = 0; y < flowfield.height; y++) {

      let px = (x + 0.5) * cellSize;

      let py = (y + 0.5) * cellSize;

      let f = flowfield.getField(x, y);

      line(px, py, px + f.x * d, py + f.y * d);

    }

  }

}

​

function addPoint(p) {

  let x = mod(ceil(p.x / minDist), dw);

  let y = mod(ceil(p.y / minDist), dh);

  distCells[x + y * dw].push(p);

}

​

function isValid(p) {

  let xp = ceil(p.x / minDist);

  let yp = ceil(p.y / minDist);

  let d = Infinity;

  for (let x = xp - 1; x <= xp + 1; x++) {

    for (let y = yp - 1; y <= yp + 1; y++) {

      let cx = mod(x, dw);

      let cy = mod(y, dh);

      let cell = distCells[cx + cy * dw];

      for (let i = 0; i < cell.length; i++) {

        let dc = dist(cell[i].x, cell[i].y, p.x, p.y);

        d = min(d, dc);

        if (d < minDist)

          return false;

      }

    }

  }

  return true;

}

​

function draw() {

  //if (frameCount % 2 == 0)

    //background(220, 120, 20, 1);

  noStroke();

  fill(255);

  s.update();

  s.draw();

}