class Vector2D
{
  float x;
  float y;
  
  Vector2D()
  {
    x = y = 0.0;
  }
  
  Vector2D( float newX, float newY )
  {
    x = newX;
    y = newY;
  }
  
  void Add( Vector2D add )
  {
    x += add.x;
    y += add.y;
  }
  
  void Multiply( float val )
  {
    x *= val;
    y *= val;
  }
  
  float DotProduct( Vector2D dot )
  {
    return( dot.x*x + dot.y*y );
  }

  void RotateByAngle( float angle )
  {
    if( angle == 0.0 )
    {
      return;
    }
    
    float tempX = x;
    float tempY = y;
    x = tempX*cos(angle) - tempY*sin(angle);
    y = tempX*sin(angle) + tempY*cos(angle);
  }
  
  float GetRadiansFromVector()
  {
    return( atan2(y, x) );
  }
      
  float Magnitude()
  {
    return( sqrt( x*x + y*y ) );
  }

  float MagnitudeSquared()
  {
    return( x*x + y*y );
  }
      
  void Normalize()
  {
    float magnitude = Magnitude();
    if( magnitude != 0.0 )
    {
      x /= magnitude;
      y /= magnitude;
    }
  }
  
  void Negative()
  {
    x = -x;
    y = -y;
  }
  
  void Zero()
  {
    x = y = 0.f;
  }
  
  void Set( float X, float Y )
  {
    x = X;
    y = Y;
  }
}