As computing becomes more ubiquitous in our objects, designers need to be more aware of how to design meaningful interactions into electronically enhanced objects. At the University of Washington, a class of junior Interaction Design majors is exploring this question. These pages chronicle their efforts.

Thursday, April 5, 2012

Assignment 1: Ryan's Processing Assignment

In this application I chose to modify a program to simulate the flocking behavior. This program traces the path of all the rockets. Clicking on the screen will create a rocket - watch the rockets interact as they get near to each other.


/**
 * Flocking 2
 * by Ryan Sun.
 *
 * An implementation of Craig Reynold's Boids program to simulate
 * the flocking behavior of birds. Each boid steers itself based on
 * rules of avoidance, alignment, and coherence.
 *
 * Click the mouse to add a new boid.
 */

int dots = 1000;
float[] dX = new float[dots];
float[] dY = new float[dots];

float l_0 = 0.0;
float h_0 = 0.0;

float legX = 0.0;
float legY = 0.0;
float thighX = 0.0;
float thighY = 0.0;

float l = 60.0; // Length of the 'leg'
float h = 90.0; // Height of the 'leg'

float nmx, nmy = 0.0;
float mx, my = 0.0;

int currentValue = 0;
int valdir = 1;

Flock flock;

void setup()

{
  size(640, 360);
  noStroke();
  flock = new Flock();
  // Add an initial set of boids into the system
  for (int i = 0; i < 0; i++) {
    flock.addBoid(new Boid(new PVector(width/2,height/2), 3.0, 0.05));
  }
  smooth();
  background(20,40,80);
}

void draw()

{
  flock.run();
}

// Add a new boid into the System
void mousePressed() {
  flock.addBoid(new Boid(new PVector(mouseX,mouseY),2.0f,0.05f));
}

// The Boid class

class Boid {

  PVector loc;
  PVector vel;
  PVector acc;
  float r;
  float maxforce;    // Maximum steering force
  float maxspeed;    // Maximum speed

    Boid(PVector l, float ms, float mf) {
    acc = new PVector(0,0);
    vel = new PVector(random(-1,1),random(-1,1));
    loc = l.get();
    r = 2.0;
    maxspeed = ms;
    maxforce = mf;
  }

  void run(ArrayList boids) {
    flock(boids);
    update();
    borders();
    render();
  }

  // We accumulate a new acceleration each time based on three rules
  void flock(ArrayList boids) {
    PVector sep = separate(boids);   // Separation
    PVector ali = align(boids);      // Alignment
    PVector coh = cohesion(boids);   // Cohesion
    // Arbitrarily weight these forces
    sep.mult(1.5);
    ali.mult(1.0);
    coh.mult(1.0);
    // Add the force vectors to acceleration
    acc.add(sep);
    acc.add(ali);
    acc.add(coh);
  }

  // Method to update location
  void update() {
    // Update velocity
    vel.add(acc);
    // Limit speed
    vel.limit(maxspeed);
    loc.add(vel);
    // Reset accelertion to 0 each cycle
    acc.mult(0);
  }

  void seek(PVector target) {
    acc.add(steer(target,false));
  }

  void arrive(PVector target) {
    acc.add(steer(target,true));
  }

  // A method that calculates a steering vector towards a target
  // Takes a second argument, if true, it slows down as it approaches the target
  PVector steer(PVector target, boolean slowdown) {
    PVector steer;  // The steering vector
    PVector desired = target.sub(target,loc);  // A vector pointing from the location to the target
    float d = desired.mag(); // Distance from the target is the magnitude of the vector
    // If the distance is greater than 0, calc steering (otherwise return zero vector)
    if (d > 0) {
      // Normalize desired
      desired.normalize();
      // Two options for desired vector magnitude (1 -- based on distance, 2 -- maxspeed)
      if ((slowdown) && (d < 100.0)) desired.mult(maxspeed*(d/100.0)); // This damping is somewhat arbitrary
      else desired.mult(maxspeed);
      // Steering = Desired minus Velocity
      steer = target.sub(desired,vel);
      steer.limit(maxforce);  // Limit to maximum steering force
    }
    else {
      steer = new PVector(0,0);
    }
    return steer;
  }

  void render() {
    // Draw a triangle rotated in the direction of velocity
    float theta = vel.heading2D() + PI/2;
    fill(200,1,1);
    stroke(255);
    pushMatrix();
    translate(loc.x,loc.y);
    rotate(theta);
    beginShape(TRIANGLES);
    vertex(0, -r*5);
    vertex(-r, r*2);
    vertex(r, r*2);
    endShape();
    popMatrix();
  }
 
  // Wraparound
  void borders() {
    if (loc.x < -r) loc.x = width+r;
    if (loc.y < -r) loc.y = height+r;
    if (loc.x > width+r) loc.x = -r;
    if (loc.y > height+r) loc.y = -r;
  }


  // Separation
  // Method checks for nearby boids and steers away
  PVector separate (ArrayList boids) {
    float desiredseparation = 20.0;
    PVector steer = new PVector(0,0,0);
    int count = 0;
    // For every boid in the system, check if it's too close
    for (int i = 0 ; i < boids.size(); i++) {
      Boid other = (Boid) boids.get(i);
      float d = PVector.dist(loc,other.loc);
      // If the distance is greater than 0 and less than an arbitrary amount (0 when you are yourself)
      if ((d > 0) && (d < desiredseparation)) {
        // Calculate vector pointing away from neighbor
        PVector diff = PVector.sub(loc,other.loc);
        diff.normalize();
        diff.div(d);        // Weight by distance
        steer.add(diff);
        count++;            // Keep track of how many
      }
    }
    // Average -- divide by how many
    if (count > 0) {
      steer.div((float)count);
    }

    // As long as the vector is greater than 0
    if (steer.mag() > 0) {
      // Implement Reynolds: Steering = Desired - Velocity
      steer.normalize();
      steer.mult(maxspeed);
      steer.sub(vel);
      steer.limit(maxforce);
    }
    return steer;
  }

  // Alignment
  // For every nearby boid in the system, calculate the average velocity
  PVector align (ArrayList boids) {
    float neighbordist = 25.0;
    PVector steer = new PVector(0,0,0);
    int count = 0;
    for (int i = 0 ; i < boids.size(); i++) {
      Boid other = (Boid) boids.get(i);
      float d = PVector.dist(loc,other.loc);
      if ((d > 0) && (d < neighbordist)) {
        steer.add(other.vel);
        count++;
      }
    }
    if (count > 0) {
      steer.div((float)count);
    }

    // As long as the vector is greater than 0
    if (steer.mag() > 0) {
      // Implement Reynolds: Steering = Desired - Velocity
      steer.normalize();
      steer.mult(maxspeed);
      steer.sub(vel);
      steer.limit(maxforce);
    }
    return steer;
  }

  // Cohesion
  // For the average location (i.e. center) of all nearby boids, calculate steering vector towards that location
  PVector cohesion (ArrayList boids) {
    float neighbordist = 25.0;
    PVector sum = new PVector(0,0);   // Start with empty vector to accumulate all locations
    int count = 0;
    for (int i = 0 ; i < boids.size(); i++) {
      Boid other = (Boid) boids.get(i);
      float d = loc.dist(other.loc);
      if ((d > 0) && (d < neighbordist)) {
        sum.add(other.loc); // Add location
        count++;
      }
    }
    if (count > 0) {
      sum.div((float)count);
      return steer(sum,false);  // Steer towards the location
    }
    return sum;
  }
}

// The Flock (a list of Boid objects)

class Flock {
  ArrayList boids; // An arraylist for all the boids

  Flock() {
    boids = new ArrayList(); // Initialize the arraylist
  }

  void run() {
    for (int i = 0; i < boids.size(); i++) {
      Boid b = (Boid) boids.get(i);
      b.run(boids);  // Passing the entire list of boids to each boid individually
    }
  }

  void addBoid(Boid b) {
    boids.add(b);
  }

}



No comments:

Post a Comment