(defpackage #:texture
  (:shadow #:load)
  (:use #:cl)
  (:export #:load #:bind))

(in-package :texture)

(defclass texture ()
  ((id :accessor texture-id :initarg :id)))

(defun load (png-image-path)
  (let* ((texture (gl:gen-texture))
	 (image (png-read:read-png-file png-image-path))
	 (image-data (png-read:image-data image))
	 (image-dimensions (array-dimensions image-data))
	 (data (loop for w below (first image-dimensions)
		     nconc (loop for h below (second image-dimensions)
				 nconc (loop for c below (third image-dimensions)
					     collect (aref image-data w h c)))))
	 (format (case (png-read:colour-type image)
		   (:truecolor-alpha :rgba)
		   (:truecolor :rgb))))
    (gl:bind-texture :texture-2d texture)
    (gl:tex-parameter :texture-2d :texture-wrap-s :repeat)
    (gl:tex-parameter :texture-2d :texture-wrap-t :repeat)
    (gl:tex-parameter :texture-2d :texture-min-filter :linear)
    (gl:tex-parameter :texture-2d :texture-mag-filter :linear)
    (gl:tex-image-2d :texture-2d
		     0
		     :rgba
		     (png-read:width image)
		     (png-read:height image)
		     0
		     format
		     :unsigned-byte
		     (coerce data 'vector))
    (gl:generate-mipmap :texture-2d)
    (make-instance 'texture :id texture)))

(defmethod bind ((self texture))
  (gl:bind-texture :texture-2d (texture-id self)))