class Pellet {
  float x,y,z,vx,vy,vz,d;
  //------------------
  Pellet(){
  }
  //------------------
  void cubeFormation(int side, float maxSpeed){
    x = random(0,side)+width/2-side/2;
    y = random(0,side)+width/2-side/2;
    z = random(0,side)+width/2-side/2;
    vx = random(-maxSpeed,maxSpeed);
    vy = random(-maxSpeed,maxSpeed);
    vz = random(-maxSpeed,maxSpeed);
  }
  //------------------
  void sphereFormation(int radius, float maxSpeed){
    cubeFormation(2*radius, maxSpeed);
    if( dist(width/2,width/2,width/2,x,y,z) > radius ) cubeFormation(2*radius, maxSpeed);
    if( dist(width/2,width/2,width/2,x,y,z) > radius ) cubeFormation(2*radius, maxSpeed);
    if( dist(width/2,width/2,width/2,x,y,z) > radius ) cubeFormation(2*radius, maxSpeed);
    if( dist(width/2,width/2,width/2,x,y,z) > radius ) cubeFormation(radius, maxSpeed);
  }
  //------------------
  void setFlightPath(float vx, float vy, float vz){
    this.vx = vx;
    this.vy = vy;
    this.vz = vz;
  }
  //------------------
  void update(){
    x += vx;
    y += vy;
    z += vz;
    vx += gradX(x,y,z)*gravity;
    vy += gradY(x,y,z)*gravity;
    vz += gradZ(x,y,z)*gravity;
    d = mag(vx,vy,vz);
    vx = vx/d;
    vy = vy/d;
    vz = vz/d;
    screenImage[constrain((int)x,0,width-1)][constrain((int)y,0,width-1)] += opacity;
  }
  //------------------
  void visualize(){
    stroke( 128*noise(x,y,z),255,255,opacity);
    noFill();
    ellipse(x,y,3,3);
  }
  //------------------
  float gradX( float x, float y, float z){
    return (noise(s*x+s,s*y,s*z) - noise(s*x-s,s*y,s*z));
  }
  //------------------
  float gradY( float x, float y, float z){
    return (noise(s*x,s*y+s,s*z) - noise(s*x,s*y-s,s*z));
  }
  //------------------
  float gradZ( float x, float y, float z){
    return (noise(s*x,s*y,s*z+s) - noise(s*x,s*y,s*z-s));
  }
}
//---------------------------------------------