Untitled

<!DOCTYPE html>
<html>
  <head>
    <!--

      HeartRate, frame rate monitor and sketch.
      Author: Corban Brook @corban

      Daniel Shiffman's flocking example ported from processing to javascript using HTML5 canvas.

      Using Vlad's mjs.js matrix and vector lib for speed

    -->

    <title>HTML5 Canvas - Flocking</title>
    <script type="text/javascript" src="mjs.js"></script>
    <script type="text/javascript" src="../heartrate.js"></script>

    <script type="text/javascript">

      var cvs,
          ctx,
          width,
          height,
          mouseX = 0,
          mouseY = 0,
          FPS = 50;

      document.addEventListener("DOMContentLoaded", init, false);

      var requestFrame = function() {};

      /* The init function creates a 2d context, runs setup and starts draw loop */
      function init() {
        cvs = document.getElementById("flocking");
        ctx = cvs.getContext("2d");

        width = cvs.width, height = cvs.height;

        // Event Listeners for mouse
        cvs.addEventListener('mouseup', mouseClicked, false);
        cvs.addEventListener('mousemove', function(event) {
          mouseX = event.clientX, mouseY = event.clientY;
        }, false);

        window.heartRate = new HeartRate({ context: ctx, maxFPS: FPS, path: "../" });

        setup();

        function redraw() {
          draw();
          requestFrame();
        }

        if (typeof window.mozRequestAnimationFrame === "function") {
          (requestFrame = function() { window.mozRequestAnimationFrame(redraw); })();
        } else if (typeof window.webkitRequestAnimationFrame === "function") {
          (requestFrame = function() { window.webkitRequestAnimationFrame(redraw); })();
        } else {
          window.setInterval(redraw, 1000 / FPS);
        }
      }


      function line(x1, y1, x2, y2) {
        ctx.beginPath();
        ctx.moveTo(x1, y1);
        ctx.lineTo(x2, y2);
        ctx.stroke();
        ctx.closePath();
      }

      function stroke(r, g, b, a) {
        var prefix = a === undefined ? 'rgb(' : 'rgba(';
        ctx.strokeStyle = prefix + Array.prototype.slice.call(arguments).join(",") + ')';
      }

      function fill(r, g, b, a) {
        var prefix = a === undefined ? 'rgb(' : 'rgba(';
        ctx.fillStyle = prefix + Array.prototype.slice.call(arguments).join(",") + ')';
      }

      //---------------------------------------------------------------------------

      var BIRD_TOTAL = 100;

      var flock;
      var skip = 1;

      function setup() {
        flock = new Flock();

        // Add initial flock of birds into the system
        for (var i = 0; i < BIRD_TOTAL; i++) {
          flock.addBird(new Bird(V3.$(width/2, height/2, 0), 2, 0.05));
        }
      }

      function draw() {
        // Clear background
        fill(240, 240, 240, 0.5);
        ctx.fillRect(0, 0, cvs.width, cvs.height);

        flock.run();

        heartRate.monitor(2, 2);

        fill(40, 40, 40);
        ctx.fillText(flock.birds.length + " particles", 730, 14);
      }

      function mouseClicked() {
        // Add 50 more birds under your mouse
        for (var i = 0; i < BIRD_TOTAL; i++) {
          flock.addBird(new Bird(V3.$(mouseX, mouseY, 0), 2, 0.05));
        }
      }

      function Flock() {
        this.birds = [];
      }

      Flock.prototype.run = function() {
        for (var i = 0; i < this.birds.length; i++) {
          this.birds[i].run(this.birds); // Passing entire list of birds to each bird
        }
      };

      Flock.prototype.addBird = function(bird) {
        this.birds.push(bird);
      };

      function Bird(loc, maxSpeed, maxForce) {
        this.loc      = V3.clone(loc);
        this.vel      = V3.$(Math.random() * 2 - 1, Math.random() * 2 - 1, 0);
        this.acc      = V3.$(0, 0, 0);

        this.r        = 5;
        this.maxSpeed = maxSpeed;
        this.maxForce = maxForce;
      }

      Bird.prototype.run = function(birds) {
        this.flock(birds);
        this.update();
        this.borders();
        this.render();
      };

      // if these 3 vars are defined here a strange flocking behavior occures
      // whereas all birds fly to 0, 0 (top left corner)
      var separation = V3.$(0, 0, 0);
      var alignment = V3.$(0, 0, 0);
      var cohesion = V3.$(0, 0, 0);

      var diff = V3.$();

      var neighborDistance = 2500; // 50 squared
      var desiredSeparation = 625; // 25 squared

      Bird.prototype.flock = function(birds) {
        // if these 3 vectors are defined here each time flock is called, it works fine.
        //var separation = V3.$(0, 0, 0);
        //var alignment = V3.$(0, 0, 0);
        //var cohesion = V3.$(0, 0, 0);

        V3.set(separation, 0, 0, 0);
        V3.set(alignment, 0, 0, 0);
        V3.set(cohesion, 0, 0, 0);

        // and yes the set function does work. these vectors are all 0, 0, 0

        var sCount = 0, count = 0;

        for(var i = 0, len = birds.length; i < len; i ++) {
          var d = V3.distanceSquared(this.loc, birds[i].loc);
          if (d > 0) {
            if (d < desiredSeparation) {
              V3.sub(this.loc, birds[i].loc, diff);
              V3.normalize(diff, diff);
              V3.scale(diff, 1/(d/10), diff);
              V3.add(separation, diff, separation);
              sCount++;
            }

            if (d < neighborDistance) {
              V3.add(alignment, birds[i].vel, alignment);

              V3.add(cohesion, birds[i].loc, cohesion);
              count++;
            }
          }
        }

        if (sCount > 0) {
          V3.scale(separation, 1/sCount, separation);
          V3.scale(separation, 2.0, separation); // weight separation

          V3.add(this.acc, separation, this.acc);
        }

        if (count > 0) {
          V3.scale(alignment, 1/count, alignment);
          V3.limit(alignment, this.maxForce, alignment);

          V3.scale(cohesion, 1/count, cohesion);
          cohesion = this.steer(cohesion, false);

          V3.add(this.acc, alignment, this.acc);
          V3.add(this.acc, cohesion, this.acc);
        }
      };

      Bird.prototype.update = function() {
        // Update velocity
        V3.add(this.vel, this.acc, this.vel);

        // Limit speed
        V3.limit(this.vel, this.maxSpeed, this.vel);
        V3.add(this.loc, this.vel, this.loc);

        // Reset acceleration to zero
        V3.set(this.acc, 0, 0, 0);
      };

      Bird.prototype.seek = function(target) {
        V3.add(this.acc, this.steer(target, false), this.acc);

      };

      Bird.prototype.arrive = function(target) {
        V3.add(this.acc, this.steer(target, true), this.acc);
      };

      var desired = V3.$();
      var steer = V3.$();

      Bird.prototype.steer = function(target, slowDown) {
        //var steer = V3.$(0, 0, 0);
        //var desired = V3.sub(target, this.loc);
        V3.set(steer, 0, 0, 0);
        V3.sub(target, this.loc, desired);
        var d = V3.length(desired);

        if (d > 0) {
          V3.normalize(desired, desired);

          if (slowDown && d < 100) {
            V3.scale(desired, this.maxSpeed*(d/100), desired);
          } else {
            V3.scale(desired, this.maxSpeed, desired);
          }

          V3.sub(desired, this.vel, steer);
          V3.limit(steer, this.maxForce, steer);
        }

        return steer;
      };

      Bird.prototype.borders = function() {
        var r = this.r, loc = this.loc;

        if (loc[0] < -r)         { loc[0] = width + r; }
        if (loc[1] < -r)         { loc[1] = height + r; }
        if (loc[0] > width + r)  { loc[0] = -r; }
        if (loc[1] > height + r) { loc[1] = -r; }
      };

      Bird.prototype.render = function() {
        var theta = V3.heading2D(this.vel) + Math.PI/2;
        ctx.save(); // push matrix
          ctx.translate(this.loc[0], this.loc[1]);
          ctx.rotate(theta);
          line(0, this.r, 0, 0);
        ctx.restore(); // pop matrix
      };
    </script>
  </head>
  <body>
    <canvas id="flocking" width="800" height="600"></canvas>
    <p>Click to add more particles. Push your browser to the limit. -- @corban</p>
  </body>
</html>