anchor.diff:  		 (rotate)
   		 (sdl2:set-render-draw-color renderer
   					     255 255 255 255)
  -		 (draw-triangle *tri-verts*)
  +		 (draw-triangle *tri-verts* renderer)
   		 (sdl2:render-present renderer)
   		 )
   	       #+SWANK (update-swank))
  
positive.code:   (setf *x-res* x
  	*y-res* y))
  
  (defparameter *renderer* nil)
  (defparameter *win* nil)
  (defparameter *tex* nil)   ;; canvas
  (defparameter *pal* nil)
  
  ;;;(defun init-palette ()
  ;;;  (setq *pal* (
  
  (defun draw-line (x1 y1 z1 x2 y2 z2 &optional (renderer *renderer*))
    (let* ((p1 (sb-cga:vec x1 y1 z1))
  	 (p2 (sb-cga:vec x2 y2 z2))
  	 (tmat (sb-cga:matrix* *pmat* *vmat* *rotmat*))
  
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)
  