#|
  This file is a part of stoe project.
  Copyright (c) 2015 Renaud Casenave-Péré (renaud@casenave-pere.fr)
|#

(uiop:define-package :stoe/engine/gl-utils
    (:use :cl)
  (:export #:gl-assert
           #:gl-restart
           #:ctype-size
           #:ctype-to-gltype
           #:ltype-to-ctype))
(in-package :stoe/engine/gl-utils)

(defmacro gl-assert (&body body)
  `(progn
     ,@(loop for form in body
          collect `(prog1
                       ,form
                     (let ((err-sym (%gl:get-error)))
                       (unless (eq err-sym :zero)
                         (error "The OpenGL command `~a'~%~2iresulted in an error: ~s~%"
                                ',form err-sym)))))))

(defmacro gl-restart (form)
  `(restart-case
       (gl-assert ,form)
     (continue () :report "Continue")))

(defun ctype-size (type)
  (ecase type
    (:unsigned-char 1)
    (:unsigned-short 2)
    (:float 4)))

(defun ctype-to-gltype (ctype)
  (case ctype
    (:unsigned-char :unsigned-byte)
    (t ctype)))

(defun ltype-to-ctype (ltype len)
  (ecase ltype
    (single-float :float)
    (double-float :double)
    (t (cond
         ((< len 256) :unsigned-char)
         ((< len 65536) :unsigned-short)
         ((< len 4294967296) :unsigned-int)
         (t :uint64)))))