Swarm

Swarm

This is a re-implementation of xswarm, an old screensaver from the X11 distribution. It is running in Processing.js in your browser and is interactive -- the bright one is called the "wasp" and you can click to attract the bees.

/* Swarm demo in Processing.js * * Ported from the v.st demos. */ void setup() { size(900,900); frameRate(30); }

float limit(float x, float min, float max) { if (x < min) return min; if (x > max) return max; return x; }

class Particle { Particle() {}

    float x = random(width);
    float y = random(height);
    float vx = 0;
    float vy = 0;
    final static float dt = 1;
    final static float max_a = 4;
    final static float max_v = 29;
    final static float max_wasp_v = 15;

    void bee_move(float tx, float ty)
    {
        float dx = tx - x;
        float dy = ty - y;

        float dist = sqrt(dx*dx + dy*dy);
        if (dist == 0)
            dist = 1;

        // adjust the accelerations up to the maximum
        // add some random noise to ensure that they don't bunch
        float dvx = (dx * max_a) / dist;
        float dvy = (dy * max_a) / dist;
        vx = limit(vx + dvx, -max_v, max_v) + random(-1,1);
        vy = limit(vy + dvy, -max_v, max_v) + random(-1,1);

        x += vx;
        y += vy;
    }

    void wasp_move()
    {
        // wasp is not acceleration limited
        vx = limit(vx + random(-5,5), -max_wasp_v, max_wasp_v);
        vy = limit(vy + random(-5,5), -max_wasp_v, max_wasp_v);

        // nudge the wasp towards the center of the screen
        if (x < width/2)
            vx += random(2);
        else
            vx -= random(2);

        if (y < height/2)
            vy += random(2);
        else
            vy -= random(2);

        x += vx;
        y += vy;

        if (x < 0 || x > width)
        {
            vx = -vx;
            x += 2*vx;
        }

        if (y < 0 || y > height)
        {
            vy = -vy;
            y += 2*vy;
        }
    }

    void draw(boolean bright)
    {
        if (bright)
            stroke(255);
        else
            stroke(100);
        line(x, y, x - vx, y - vy);
    }

};

int num_bees = 50; Particle wasp; Particle[] bees; boolean wasp_follows_mouse = false;

void draw() { background(0);

  if (wasp == null)
  {
    wasp = new Particle();
    wasp.vx = 3;
    wasp.vy = 5;
    bees = new Particle[num_bees](num_bees);
    for(int i = 0 ; i < num_bees; i++)
        bees[i](i) = new Particle();
  }

  background(0);
  strokeWeight(10);


  if (mousePressed)
     wasp_follows_mouse = !wasp_follows_mouse;

  // update the wasp with the mouse
  if (wasp_follows_mouse)
  {
    wasp.vx = mouseX - wasp.x;
    wasp.vy = mouseY - wasp.y;
    wasp.x = mouseX;
    wasp.y = mouseY;
  } else {
    wasp.wasp_move();
  }

  wasp.draw(true);

  // update the bees
  strokeWeight(5);
  for(Particle bee : bees)
  {
    bee.bee_move(wasp.x, wasp.y);
    bee.draw(false);
  }

}

2015 Art Processing

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Last update: November 8, 2020