/** 
 * A particle. Everything in this universe is a particle. 
 * Nick Selvaggio
 * 12.02.09
 **/ 
class Particle { 
  
  PVector loc; 
  PVector vel;
  PVector acc;
 
  float mass; 
  
  color myColor; 
  
  float t;          //time. it keeps going.   
  float lifespan;   //its our destiny.

  //-----------------------------------------------------
  Particle(PVector location) { 
   loc = location;
   acc = new PVector(); 
   vel = new PVector(0,0);         //initial  velocity 
   mass = 5;
   lifespan = random(350); 
  
   myColor = someColor(); 
  } 
 
 
  //-------------------------------------------------------
  void render() { 
    
    //output a sphere. 
   
   
     
    //output a point.
    stroke(myColor,90);
    strokeWeight(6);  
    
    //messing around. 
    //curve(loc.x-vel.x, loc.y-vel.y, loc.x, loc.y, loc.x+vel.x, loc.y+vel.y, (loc.x-vel.x), (loc.x-vel.y)); 
    line(loc.x, loc.y, (loc.x-vel.x), (loc.y-vel.y)); 
    //point(loc.x, loc.y); 
    
    smooth();
    fill(0, 100);
    noStroke();   
    ellipse(loc.x, loc.y, mass, mass); 
}
  
  //-------------------------------------------------------
  void die() { 
     //life is over... it was fun.    
     
     //drop the particle off the screen using a gravitational force.  
     //applyForce(new PVector(0, 9.8)); 
  }
  //-------------------------------------------------------
  // Some getters. 
  float getMass() { 
    return mass; 
  }
  
  PVector getLoc() { 
    return loc; 
  }
  //-------------------------------------------------------
  void checkWalls() { 
     //lets check our boundaries. 
     if(loc.x > width || loc.x < 0) { 
       vel.x = -vel.x; 
     }  
   
     if(loc.y > height || loc.y < 0) { 
       vel.y = -vel.y;  
     }
  }
  //-------------------------------------------------------
  void lineTo(Particle p) { 
     smooth(); 
     stroke(255); 
     line(loc.x, loc.y, p.loc.x, p.loc.y); 
  } 
}