// Learning Processing
// Daniel Shiffman
// http://www.learningprocessing.com

// Example 23-4: Super fancy ArrayList and rectangle particle system

// A simple Particle Class
class Particle {
  
  float x;
  float y;
  float xspeed;
  float yspeed;
  float life;
  
  // Make the Particle
  Particle(float tempX, float tempY) {
    x = tempX;
    y = tempY;
    xspeed = random(-1,1);
    yspeed = random(-2,0);
    life = 255;
  }
  
  // Move
  void run() {
    x = x + xspeed;
    y = y + yspeed;
  }
  
  // Fall down
  void gravity() {
    yspeed += 0.1;
  }
  
  // Stop moving
  void stop() {
    xspeed = 0;
    yspeed = 0;
  }
  
  // Ready for deletion
  boolean finished() {
    // The Particle has a "life" variable which decreases.
    // When it reaches 0 the Particle can be removed from the ArrayList.
    life -= 2.0; 
    if (life < 0) return true;
    else return false;
  }
  
  // Show
  void display() {
    // Life is used to fade out the particle as well
    stroke(0, life);
    fill(175,life);
    ellipse(x,y,10,10);
  }
}