;;; glut-template.lisp

;;; load opengl
(require :asdf)
(asdf:load-system :cl-opengl)
(asdf:load-system :cl-glu)
(asdf:load-system :cl-glut)


(defclass my-window (glut:window)
  ()
  (:default-initargs :width 400 :height 300
		     :title "My Window Title"
		     :x 100 :y 100
		     :mode '(:double :rgb :depth)))


;;; initilization method
(defmethod glut:display-window :before ((win my-window))
  ;;; prepage opengl
  (gl:shade-model :smooth) ; enables smooth shading
  (gl:clear-color 0 0 0 0) ; background will be black
  (gl:clear-depth 1)       ; clear buffer to minimum depth
  (gl:enable :depth-test)  ; enable depth testing
  (gl:depth-func :lequal) ; okay to write pixel if its depth
			      ; is less-than-or-equal to the
                              ; depth xcurrently written
  (gl:hint :perpective-correction-hint :nicest) ; really nice perspective correction
)


;;; additional glut methods
(defmethod glut:display ((win my-window))
  (gl:clear :color-buffer-bit :depth-buffer-bit)
  (gl:load-identity))

(defmethod glut:reshape ((win my-window) width height)
  ;;; prepare viewport
  (gl:viewport 0 0 width height) ; reset current viewport
  ;;; glut reshape  -- prepare project
  (gl:matrix-mode :projection) ; select the projection matrix
  (gl:load-identity) ; reset the matrix
  ;; set perspective based on window aspect ratio
  (glu:perspective 45 (/ width (max height 1)) 1/10 100)

  ;;; glut reshape -- switch to model view
  (gl:matrix-mode :modelview) ;select the model view matrix
  (gl:load-identity) ; reset the matrix
)



;;; create an instance of our window
(glut:display-window (make-instance 'my-window))