// a class containing all the features and
// control structures of a spermie
class spurmie
{
  renderspurmie display;
  Position myPos;
  Position myVector;
  Position mySpeed;
  float sgnX = 1;
  float sgnY= 1;
  
  spurmie(float xPos, float yPos)
  {
    myPos = new Position(xPos,yPos);
    myVector = new Position(0,0);
    float sp = random(0.03,0.3);
    mySpeed = new Position(sp,sp);
    myPos.setEdgeOnOff(true);
    display = new renderspurmie(color(128,192,0));
    
    sgnX = random(-1,1) > 0 ?  1 :-1;
    sgnY = random(-1,1) > 0 ?  1 :-1;
  }
  
  void update()
  {
    //display.eraseAt(myPos,myVector);
    recalcMyPos();
    display.drawAt(myPos,myVector);
  }
  
  void recalcMyPos()
  {
    Position goalPos;
    if(daynight.IsDay())
    {
      goalPos = daynight.getSunPos();
    }
    else
    {
      float y = myPos.getY() + 0.05;
      float x = myPos.getX() + 0.05;
      goalPos = new Position(sgnX*x,sgnY*y);
    } 
    float hyp = sqrt(sq( myPos.getX()-goalPos.getX()) + sq( myPos.getY()-goalPos.getY()));
    float adj = goalPos.getX() - myPos.getX();
    float opp = goalPos.getY() - myPos.getY();
    myVector.setX( adj/hyp );
    myVector.setY( opp /hyp );
    myPos.setX(myPos.getX() + mySpeed.getX()*myVector.getX()); 
    myPos.setY(myPos.getY() + mySpeed.getY()*myVector.getY()); 
  }
}

class renderspurmie
{
  color myColor;
  int radius = 4;
  int tailLen = 24;
  renderspurmie(color c)
  {
    myColor = c;
  }
  
  void drawAt(Position pos, Position vect)
  {
    noStroke();
    fill(myColor);
    ellipse(pos.getX(),pos.getY(),radius*2,radius*2);
    stroke(myColor);
    drawTail(pos,vect);
    //line(pos.getX()+radius,pos.getY(),pos.getX()+radius+tailLen,pos.getY());
  }

  void eraseAt(Position pos, Position vect)
  {
    noStroke();
    fill(daynight.currentSky());
    ellipse(pos.getX(),pos.getY(),radius*2,radius*2);
    stroke(daynight.currentSky());
    drawTail(pos,vect);
    //line(pos.getX()+radius, pos.getY(),pos.getX()+radius+tailLen,pos.getY());
  }
  
  void drawTail(Position pos, Position vect)
  {
    float startX = pos.getX() - radius*vect.getX();
    float startY = pos.getY() - radius*vect.getY();
    float endX = pos.getX()-(radius+tailLen)*vect.getX();
    float endY= pos.getY()-(radius+tailLen)*vect.getY();
    line(startX,startY,endX,endY);
  }
}