Hi, this is a question about how to run a code in DrRacket which displays a 3D (volumetric) texture in an OpenGL window. Displaying a 2D Texture works beautifully. Displaying a 3D Texture returns an Error: Racket\collects\sgl\gl.rkt:21:23: glTexImage3D: unavailable on this system (I`m working on the windows version of DrRacket) Does anybody know about the implementation of sgl/gl.rkt in detail ? The problem is, i think, in the following: The following C++ GLUT code works fine on my machine and needs an external DLL glut32.dll and a dynamic load of the function "glTexImage3D" on the run. However, Racket\collects\sgl\gl.rkt only creates FFI functions for C:\Windows\system32\glu32.dll where the OpenGL extensions are not available in glu32.dll . Is there a book, or an example code which could help showing that Racket can do magic with OpenGL in a REPL on volumetric textures ? Backup plan: is there a good book on MZScheme, FFI, dynamic loading of DLL functions ? (The mzscheme examples in DrRacket don`t seem to work out of the box on Windows) I have experience with SBCL and C++, Racket is fairly new to me. -------------------- Here is what I tried so far: I used and modified the following code by Brendan Burns with modifications by Scott Owens: C:\Program Files\Racket\collects\sgl\examples\alpha.rkt C:\Program Files\Racket\collects\sgl\examples\gl-frame.rkt which displays 2D textures on a cube. The following C++ GLUT code works fine on my machine, needs an external DLL glut32.dll. However, Racket\collects\sgl\gl.rkt only creates FFI functions for C:\Windows\system32\glu32.dll where the OpenGL Extensions are not available. ... #include <GL/glext.h> ... // VERY IMPORTANT: // this line loads the address of the glTexImage3D function into the function pointer of the same name. // glTexImage3D is not implemented in the standard GL libraries and must be loaded dynamically at run time, // the environment the program is being run in MAY OR MAY NOT support it, if not we'll get back a NULL pointer. // this is necessary to use any OpenGL function declared in the glext.h header file // the Pointer to FunctioN ... PROC types are declared in the same header file with a type appropriate to the function name glTexImage3D = (glTexImage3D) wglGetProcAddress("glTexImage3D"); if (glTexImage3D == NULL) { printf("Error in line %d: Couldn't load glTexImage3D function. Aborting.\n", __LINE__); return -1; } ... The code displays a nice 3D texture on a pyramid. Now trying to do the same in DrRacket: ;;----------- Code Excerpt for GL_TEXTURE_3D ------------- (glEnable GL_3D) (glEnable GL_TEXTURE_3D) ... ;; --- Create a 3D texture for OpenGL --- (define (get-tex3d fname) (let* ((xx 4) (yy 6) (zz 12) (pixels (* xx yy zz)) (vec (make-gl-ubyte-vector (* pixels 3))) (data (make-bytes (* pixels 4))) (i 0) (cr (round (* (/ 255 pixels) 1))) ; color range increment from pixel to pixel ) (letrec ([loop (lambda () (if ( (begin (gl-vector-set! vec (* i 3) (- 255 (round (* cr i)))) (gl-vector-set! vec (+ (* i 3) 1) (round (* cr i))) (gl-vector-set! vec (+ (* i 3) 2) (- 124 (round (* (/ cr 2) i)))) (set! i (+ i 1)) (loop))))]) (loop)) (list xx yy zz vec))) ;; ---------- Try to Load a 3D openGL texture into OpenGL ---------- (define gl-load-texture3d (lambda (image-vector width height depth min-filter mag-filter ix) (glBindTexture GL_TEXTURE_3D (gl-vector-ref *textures* ix)) (glTexParameteri GL_TEXTURE_3D GL_TEXTURE_MIN_FILTER min-filter) (glTexParameteri GL_TEXTURE_3D GL_TEXTURE_MAG_FILTER mag-filter) (let* ((new-img-vec (make-gl-ubyte-vector (* width height depth 3))) ; (new-img-vec image-vector) ) (if (or (= min-filter GL_LINEAR_MIPMAP_NEAREST) (= mag-filter GL_LINEAR_MIPMAP_NEAREST)) (gluBuild3DMipmaps GL_TEXTURE_3D 3 width height depth GL_RGB GL_UNSIGNED_BYTE new-img-vec) ;; this is not supported in my Racket ! ? ! (glTexImage3D GL_TEXTURE_3D 0 3 width height depth 0 GL_RGB GL_UNSIGNED_BYTE new-img-vec) ;; this is not supported in my Racket ! ? ! ))) ) ;;... ;; Perform the 3D Texture Load (unless (gl-load-texture3d (list-ref res 3) (list-ref res 0) (list-ref res 1) (list-ref res 2) GL_NEAREST GL_NEAREST 0) (error "Couldn't load texture")) Thank you for your comments. mosi