anchor.diff:  	   ;;    (aref tri i) tv x y)
   	   (setf (aref coords (* 2 i))       (round x)
   		 (aref coords (1+ (* 2 i)))  (round y))))
  -    (let ((ptr (autowrap:ptr (sdl2-ffi.functions:sdl-get-window-surface *win*))))
  -      (loop for x below 8000 do
  -	   (setf (cffi:mem-ref ptr :unsigned-char 
  -			       (random 160000))
  -			     (random 255))))
       (sdl2:render-draw-line 
        renderer
        (aref coords 0) (aref coords 1)
  
positive.code:     
  (let ((coords (make-array 6 :element-type
  			  '(signed-byte 32))))
    (defun draw-triangle (tri &optional (renderer *renderer*))
      (loop for i below 3 do
  	 (let* ((tmat (sb-cga:matrix* *pmat* *vmat* *rotmat*))
  		(tv (sb-cga:transform-point 
  
negative.code:      renderer
       sx1 sy1 sx2 sy2)))
  
  (defun draw-axes (renderer)
    (sdl2:set-render-draw-color renderer 255 0 0 255)
    (draw-line 0.0 0.0 0.0 1.0 0.0 0.0 renderer)
    (sdl2:set-render-draw-color renderer 0 255 0 255)
  