anchor.diff:  
    
  +(defun key-pressed-p (scancode)
  +  (sdl2:keyboard-state-p scancode))
   
   (defun click-handler (x y)
     (add-boid x y)
  
positive.code:     (gl:with-pushed-matrix
        (p2dglu:translate2 position)
        (p2dglu:color4 color)
        (p2dglu:rotatez* orientation)
        (gl:scale 8 10 8)
        (p2dglu:draw-triangle))))
  
  
negative.code: (defparameter +min-boid-distance-to-game-area-boundary+ 30)
  
  (defparameter +boid-perception-range+ 50)
  
  (defparameter +player-base-speed+ 30)
  (defparameter +player-running-speed+ 60)
  (defparameter +player-slow-speed+ 10)
  (defparameter +player-angular-speed+ p2dm:+pi+)
  
  
  