//import processing.opengl.*;
ParticleSystem ps;

void setup() {
  //size(screen.width, screen.height, OPENGL);
  size(1200,900);
  frameRate(35);
  smooth(); 
  fill(226);
  ps = new ParticleSystem();

}


void  draw() {
  ps.draw();
}



/*********************
*********************/
class ParticleSystem{
  int tickIndex = 0;
  int NUM_PARTICLES = 40;
  Particle[] particles;
  float minDist = 100;
  float springAmount = 0.0001;
  float attractAmount = 0.01;
  Attractor attractor;
 // float maxVelocity = 
  
  ParticleSystem() {
    
    particles = new Particle[NUM_PARTICLES+1];
    
    for(int i=0; i<NUM_PARTICLES; i++) {
      Particle par = particles[i] = new Particle();
      par.vx = random(6) - 3;
      par.vy = random(6) - 3;
    }
    
    //mouse attractor
    attractor = new Attractor();
      
  }
  
  void  draw() {
    background(51,51,51);
    for(int i=0; i<NUM_PARTICLES; i++) {
       Particle par =  particles[i];
       par.x += par.vx;
       par.y += par.vy;
       par.draw(); 
  }
   
  mouseTick();
  tick();
}
  
  void mouseTick() {
    attractor.x = mouseX;
    attractor.y = mouseY;
    //attract each particle to our attractor
    for(int i=0; i<NUM_PARTICLES; i++) {
     Particle a = particles[i];
       attract(attractor, a);
   }
  }
  
  void tick() {
    
      //attract each particle to themselves
      for(int i=0; i<NUM_PARTICLES; i++) {
         Particle a = particles[i];
         for(int j=0; j<NUM_PARTICLES; j++) {
           Particle b = particles[j];
           if(tickIndex%1 == 0) {
             spring(a, b);
             
           }
           
         }
       } 
     tickIndex++;
   }
    

  
  
  void spring(Particle a, Particle b) {
    float dx = b.x - a.x;
    float dy = b.y - a.y;
    float distance = sqrt(dx*dx + dy*dy);
    if(distance<minDist) {
      //contstrain our velocities
      a.contstainVelocity();
      b.contstainVelocity();
      
      //draw line
      stroke(256,256,256,distance/minDist*100);
      line(a.x, a.y, b.x, b.y);
      
      float ax = dx * springAmount;
      float ay = dy * springAmount;
      a.vx += ax / a.mass;
      a.vy += ay / a.mass;
      b.vx -= ax / b.mass;
      b.vy -= ay / b.mass;
    }
  }
  
  void attract(Attractor a, Particle b) {
    float dx = b.x - a.x;
    float dy = b.y - a.y;
    float distance = sqrt(dx*dx + dy*dy);
      float ax = dx * attractAmount;
      float ay = dy * attractAmount;
      a.vx += ax / a.mass;
      a.vy += ay / a.mass;
      b.vx -= ax / b.mass;
      b.vy -= ay / b.mass;
  }
  
}



/*********************
*********************/
class Attractor {
  
 float WIDTH = 5;
 float vx = 0;
 float vy = 0;
 float mass = 2;
 float x;
 float y; 
 
 Attractor() {
   x = mouseX;
   y = mouseY;
 }

 void draw() {
    //
 }

}





/*********************
*********************/
class Particle {
  
 float vx = 0;
 float vy = 0;
 float mass;
 float x;
 float y; 
 
 Particle() {
   x = random(width);
   y = random(height);
   mass = random(1)+1;
 }
 
 void contstainVelocity() {
   if(vx>10) {
       vx = 10;
   }else if(vx<-10){
      vx =  -10;
   }
   if(vy>10) {
       vy = 10;
   }else if(vy<-10){
      vy =  -10;
   }
 }

 void draw() {
   
   
    if(x>width) {
      x = 0;
    }else if(x < 0) {
      x = width;
    }
    if(y>height) {
      y = 0;
    }else if(y<0) {
      y = height;
    }
				
   
   fill(255,255,0);
   ellipse( x, y, mass*5, mass*5);
 }

}