+(defun true-load-texture (filename min-filter mag-filter static)
+ (let ((key (make-resource-texture :filename filename :min-filter min-filter :mag-filter mag-filter)))
+ (progn-textures
+ (multiple-value-bind
+ (image real-w real-h) (load-image-for-texture filename)
+ (cond (image
+ (let ((width (surface-w image)) (height (surface-h image))
+ (byteorder (if (= (SDL_ByteOrder) SDL_LIL_ENDIAN)
+ (if (= (surface-format-BytesPerPixel image) 3) GL_BGR GL_BGRA)
+ (if (= (surface-format-BytesPerPixel image) 3) GL_RGB GL_RGBA)))
+ (texture (car (glGenTextures 1))))
+ (glBindTexture GL_TEXTURE_2D texture)
+ (glTexImage2D GL_TEXTURE_2D 0 3 width height 0 byteorder GL_UNSIGNED_BYTE (surface-pixels image))
+ (glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MIN_FILTER min-filter)
+ (glTexParameteri GL_TEXTURE_2D GL_TEXTURE_MAG_FILTER mag-filter)
+ (SDL_FreeSurface image)
+ (set-resource key
+ `(:id-texture ,texture :width ,real-w :height ,real-h)
+ (lambda () (true-load-texture filename min-filter mag-filter static))
+ (lambda () (glDeleteTextures 1 `(,texture)))
+ :static static)
+ key)))))))
+
+(defun draw-image-function (filename)
+ (multiple-value-bind
+ (texture width height) (load-texture filename)
+ (lambda (&optional (f 1))
+ (cond (texture
+ (draw-rectangle (* f width) (* f height) :texture texture))))))
+
+(defun draw-quad (v1 v2 v3 v4 &key texture)
+ (cond (texture (progn-textures
+ (glBindTexture GL_TEXTURE_2D (getf texture :id-texture))
+ (begin-draw 4)
+ (draw-vertex v1 :texture-coord '(0 0))
+ (draw-vertex v2 :texture-coord '(1 0))
+ (draw-vertex v3 :texture-coord '(1 1))
+ (draw-vertex v4 :texture-coord '(0 1))
+ (glEnd)))
+ (t (draw v1 v2 v3 v4))))
+
+(defun draw-rectangle (width height &key texture)
+ (let* ((w (/ width 2)) (-w (neg w)) (h (/ height 2)) (-h (neg h)))
+ (draw-quad (list -w h 0) (list w h 0) (list w -h 0) (list -w -h 0) :texture texture)))
+
+(defun draw-square (&key (size 1) texture)
+ (draw-rectangle size size :texture texture))
+
+(defun draw-cube (&key size texture)