Re: Function set-gl-vertex-array in Guile-opengl

[Luis Souto Graña]

You're right. I suposse I was missing the argument type, I thought that
"type
bv-or-pointer" was one thing.

I'm in Manjaro. I just did:
Unzip guile-opengl-0.10.tar.gz
$ ./configure --prefix=/usr
$ make
$ sudo make install

And glut works well with (use-modules (gl) (glut))

The example of a circle works:

(use-modules (gl) (glut))

(define PI 3.14159265358979324)
(define radius 40.0)   ; radius of circle
(define x-center 50.0)  ; x-coordinate of center of circle
(define y-center 50.0)  ; y-coordinate of center of circle
(define num-vertices 5) ; number of vertices on circle
(define t 0.0)        ; angle parameter

(define (init)
    (gl-ortho 0.0 100.0 0.0 100.0 -1.0 1.0)
    (set-gl-clear-color 1.0 1.0 1.0 0.0))

(define (draw-scene)
    (gl-clear (clear-buffer-mask color-buffer))
    (gl-color 0 0 0)
    (gl-begin (begin-mode line-loop)
        (do ((i 1 (1+ i)))((> i num-vertices))
            (gl-vertex (+ x-center (* radius (cos t)))
                       (+ y-center (* radius (sin t)))
                       0.0)
            (set! t (+ t (/ (* 2 PI) num-vertices))))))

(define (on-display)
    (init)
    (draw-scene)
    (swap-buffers))

(initialize-glut #:window-size '(500 . 500))
(make-window "circle")
(set-display-callback (lambda() (on-display)))
(glut-main-loop)

El sáb., 26 ene. 2019 a las 11:34, Catonano (<address@hidden>) escribió:

> Hi Luis,
>
> I hadn't guile-opengl installed, so I downloaded, built it and installed
> it uust to see if I could reproduce this error you are running into
>
> Il giorno ven 25 gen 2019 alle ore 15:58 Luis Souto Graña <
> address@hidden> ha scritto:
>
>> Hello, I'm trying to use the function set-gl-vertex-array in Guile-opengl
>> .
>> It needs a bytevector as an argument. I wrote this doing a copy-paste from
>> here:
>> https://github.com/marcomaggi/vicare/blob/master/attic/lab/gears.scm
>>
>> (use-modules (rnrs bytevectors))
>> (use-modules (system foreign))
>>
>> (define (f32vector . lst)
>>   (define-syntax f32set!
>>     (syntax-rules ()
>>       ((_ bv n value)
>>        (bytevector-ieee-single-native-set! bv (* n 30) value))))
>>   (let ((bv (make-bytevector (* (length lst) 30))))
>>     (let loop ((i 0) (lst lst))
>>       (cond ((null? lst) bv)
>>         (else
>>          (f32set! bv i (car lst))
>>          (loop (+ i 1) (cdr lst)))))))
>>
>
>
> In my test I used the f32vector that comes with guile, I don't know how
> it's different from the one you are defining here
>
>
>
>>
>> (define points (f32vector 30.0 30.0 0.0
>>                       10.0 10.0 0.0
>>                       70.0 30.0 0.0
>>                       90.0 10.0 0.0
>>                       70.0 70.0 0.0
>>                       90.0 90.0 0.0
>>                       30.0 70.0 0.0
>>                       10.0 90.0 0.0
>>                       30.0 30.0 0.0
>>                       10.0 10.0 0.0))
>>
>
> Ok
>
>
>
>> > points
>> #vu8(0 0 240 65 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
>> 240
>>
>
>
> in my case it's
>
> scheme@(guile-user)> points
> $1 = #f32(30.0 30.0 0.0 10.0 10.0 0.0 70.0 30.0 0.0 90.0 10.0 0.0 70.0
> 70.0 0.0 90.0 90.0 0.0 30.0 70.0 0.0 10.0 90.0 0.0 30.0 30.0 0.0 10.0 10.0
> 0.0)
>
> I guess the difference is due to the fact that I used the one provided by
> Guile
>
> .....
>>
>> > (bytevector-length points)
>> 900
>>
>
>
> In my case:
>
> scheme@(guile-user)> (bytevector-length points)
> $2 = 120
>
>
>
>> > (bytevector->pointer points)
>> #<pointer 0x56090d909aa0>
>>
>
>
> scheme@(guile-user)> (bytevector->pointer points)
> $3 = #<pointer 0x5578953d25c0>
>
>
>>
>>
>> So, it works well.
>>
>> Now, if I write:
>>
>> (use-modules (gl) (glut))
>>
>> > ,apropos set-gl-vertex-array
>> (gl): set-gl-vertex-array    #<procedure set-gl-vertex-array (type
>> bv-or-pointer #:optional size #:key stride offset)>
>>
>>
>> > (set-gl-vertex-array (bytevector->pointer points) 3)
>>
>> ERROR: In procedure scm-error:
>> unhandled array-pointer type 3
>>
>
>
>
> The first remark: the documentation you get with ,apropos reports:
>
> (gl): set-gl-vertex-array    #<procedure set-gl-vertex-array (type
> bv-or-pointer #:optional size #:key stride offset)>
>
> The function requires the first argument to be a "type" and the second
> argument to be a pointer to a bytevector
>
> Now in your call to the function, the first argument you are passing is
> not a type, it's a pointer to a bytevector
>
> And the second argument is an integer number (3)
>
> I don't now if the convention to express the types this function expects
> is to use numbers (like in enumerations), it might be
>
> But the way you're calling it seems incorrect
>
> If you try to call it with a type first and then a pointer to a
> bytevector, you might get a more interesting result
>
> In my case what I found out is that the linking to opengl is broken
>
> scheme@(guile-user)> (set-gl-vertex-array 3 (bytevector->pointer points) )
> ERROR: In procedure dynamic-link:
> In procedure dynamic-link: file: "libglut", message: "file not found"
>
> Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
> scheme@(guile-user) [1]>
>
>
> So the libglut file can't be found
>
> The libglut file should have been identified during the configuration
> phase when I built guile-opengl
>
> But it hasn't, it seems
>
> I took a quick look at the guile-opengl configure.ac file and there's no
> attempt at finding libglut
>
> Also, the compiled files get installed in
> $(libdir)/guile/$(GUILE_EFFECTIVE_VERSION)/ccache
>
> all the other guile packages I have are installed in site-ccache, not in
> ccache
>
> So when I ,use the glut related namespaces in the REPL they get compiled
> right there and then
>
> I wondered if the unreachable ones in ccache are able to find libglut,
> maybe because of some automagic mechanism I don't know about
>
> I tried to fix the position for compiled files in the Automake.am file but
> the problem persists
>
> So this seems to be a lacking in the guile-opengl package
>
> In fact, I see that the only contributor to guile-opengl is Andy Wingo
>
> And putting the compiled files in ccache instead of site-ccache was a
> thing in guile-fibers too
>
> All other guile packages I have, put compiled files in site-ccache, I
> don't know why Andy has this habit and other packages have a different
> habit ¯\_(ツ)_/¯
>
> Often package authors can't deal with the Autotools, it seems to be too
> hard not only for me. But I doubt Andy has this kind of difficutly, I
> wonder why this is
>
> That said, being on Ubuntu 18.04.1 what should I install in order to have
> libglut on my system ?
> I see a libgle3 that seems a good candidate. Is that the right one ?
>
> If I had it I could try to sift through the internet myself and see if I
> can improve the Autotools setup of guile-opengl
>
> From there on, you could explore the code more freely.
>
> OR you could already have a better installation than I have, I don't know
> ¯\_(ツ)_/¯
>