int NUM_LINES = 1000;

Line pline;
ParticleLines plines;
float radius = 100;
int cx, cy;

void setup(){
  size(800,800,P3D);

  float theta = random(0,TWO_PI);
  float u = random(-1,1);
  pline = new Line(theta,u);
  plines = new ParticleLines();

  stroke(random(255),random(255),random(255));
  frameRate(30);
}

void draw(){
  background(0);
  camera(0,0,500,0,0,0,0,1,0);

  pushMatrix();
  rotateY(map(mouseX,0,width,0,TWO_PI));
  rotateX(map(mouseY,0,height,0,TWO_PI));
  plines.update();
  plines.render();
  popMatrix();
}

class ParticleLines {  
  Line[] lines = new Line[NUM_LINES]; 

  void ParticleLines(){
    for(int i=0; i<NUM_LINES; i++){
	float theta = random(0,TWO_PI);
	float u = random(-1,1);
	lines[i] = new Line(theta, u);
    }
  } 

  void update(){
    for(int i=0; i<NUM_LINES; i++){
	lines[i].update();
    }
  }

  void render(){
    for(int i=0; i<NUM_LINES; i++){
	lines[i].render();
    }
  }
}


class Line {  
  float theta, u;
  float vtheta, vu;
  float x,y,z;

  void Line(float _theta, float _u) {
    theta = _theta;
    u = _u;
    vtheta = 0;
    vu = 0;
  } 

  void update(){
    vtheta += random(-0.001, 0.001);
    theta += vtheta;    
    if(theta<0 || theta>TWO_PI) vtheta *= -1;    
    vu += random(-0.001, 0.001);
    u += vu;    
    if(u<-1 || u>1) vu *= -1;    
    vu *= 0.95;
    vtheta *= 0.95;    
    x = radius * cos(theta) * sqrt(1-(u*u));
    y = radius * sin(theta) * sqrt(1-(u*u));
    z = u*radius;
  }

  void render(){
    pushMatrix();
    //translate(width,y,z);
    line(0,0,0,x,y,z);
    popMatrix(); 
  }
}