Problem with contexts in Windows.

[LeifAndersen]

The follow program will not work in windows:

#lang at-exp racket/base

(provide video-canvas%)
(require opengl
         racket/class
         racket/gui/base)

(define video-canvas%
  (class canvas%
    (super-new [style '(gl no-autoclear)])
    (send this with-gl-context
          (λ ()
            (glGetString GL_VERSION)))))

(define f (new frame% [label "test"]))
(define c (new video-canvas%
               [parent f]))

I get the error:

OpenGL procedure not available: glGetString
  context...:
   C:\Users\Leif Andersen\AppData\Roaming\Racket\snapshot\pkgs\opengl\opengl\main.rkt:74:7
   C:\Program Files\Racket-6.10.0.1\collects\racket\contract\private\arrow-val-first.rkt:357:18
   C:\Program Files\Racket-6.10.0.1\collects\racket\private\class-internal.rkt:3553:0: continue-make-object
   C:\Program Files\Racket-6.10.0.1\collects\racket\private\class-internal.rkt:3507:0: do-make-object
   C:\Users\Leif Andersen\Documents\GitHub\video\video\private\video-canvas.rkt: [running body]

However, when I switch the (require opengl) line to (require sgl/gl), it now works. And I when I display the resulting version I get:

4.5.0 NVIDIA 382.05

This makes me think it is a problem with the opengl bindings in this package, rather than a bug in the context created by Racket.

[stephanh42]

Hi Leigh, This is because you are getting a core context (See https://www.khronos.org/opengl/wiki/Core_And_Compatibility_in_Contexts) glGetString is not available in core contexts. Basically, the code as it stands today doesn't work in core contexts. It would need to be adapted to work with that. Stephan 2017-08-04 5:19 GMT+02:00 Leif Andersen <notifications@github.com>:

…

The follow program will not work in windows: #lang at-exp racket/base #| Copyright 2016-2017 Leif Andersen Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. |# (provide video-canvas%) (require opengl racket/class racket/gui/base) (define video-canvas% (class canvas% (super-new [style '(gl no-autoclear)]) (send this with-gl-context (λ () (glGetString GL_VERSION))))) (define f (new frame% [label "test"])) (define c (new video-canvas% [parent f])) I get the error: OpenGL procedure not available: glGetString context...: C:\Users\Leif Andersen\AppData\Roaming\Racket\snapshot\pkgs\opengl\opengl\main.rkt:74:7 C:\Program Files\Racket-6.10.0.1\collects\racket\contract\private\arrow-val-first.rkt:357:18 C:\Program Files\Racket-6.10.0.1\collects\racket\private\class-internal.rkt:3553:0: continue-make-object C:\Program Files\Racket-6.10.0.1\collects\racket\private\class-internal.rkt:3507:0: do-make-object C:\Users\Leif Andersen\Documents\GitHub\video\video\private\video-canvas.rkt: [running body] However, when I switch the (require opengl) line to (require sgl/gl), it now works. And I when I display the resulting version I get: 4.5.0 NVIDIA 382.05 This makes me think it is a problem with the opengl bindings in this package, rather than a bug in the context created by Racket. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#20>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAsR3ktvBtlSZMJfc7JD8YFh52htTqhqks5sUo3NgaJpZM4OtOxC> .

[stephanh42]

2017-08-04 12:32 GMT+02:00 Stephan Houben <stephanh42@gmail.com>:

Hi Leigh,

Sorry, my apologies: "Hi Leif," of course. Stephan

…

This is because you are getting a core context (See https://www.khronos.org/opengl/wiki/Core_And_ Compatibility_in_Contexts) glGetString is not available in core contexts. Basically, the code as it stands today doesn't work in core contexts. It would need to be adapted to work with that. Stephan 2017-08-04 5:19 GMT+02:00 Leif Andersen ***@***.***>: > The follow program will not work in windows: > > #lang at-exp racket/base > > #| > Copyright 2016-2017 Leif Andersen > > Licensed under the Apache License, Version 2.0 (the "License"); > you may not use this file except in compliance with the License. > You may obtain a copy of the License at > > http://www.apache.org/licenses/LICENSE-2.0 > > Unless required by applicable law or agreed to in writing, software > distributed under the License is distributed on an "AS IS" BASIS, > WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. > See the License for the specific language governing permissions and > limitations under the License. > |# > > (provide video-canvas%) > (require opengl > racket/class > racket/gui/base) > > (define video-canvas% > (class canvas% > (super-new [style '(gl no-autoclear)]) > (send this with-gl-context > (λ () > (glGetString GL_VERSION))))) > > (define f (new frame% [label "test"])) > (define c (new video-canvas% > [parent f])) > > I get the error: > > OpenGL procedure not available: glGetString > context...: > C:\Users\Leif Andersen\AppData\Roaming\Racket\snapshot\pkgs\opengl\opengl\main.rkt:74:7 > C:\Program Files\Racket-6.10.0.1\collects\racket\contract\private\arrow-val-first.rkt:357:18 > C:\Program Files\Racket-6.10.0.1\collects\racket\private\class-internal.rkt:3553:0: continue-make-object > C:\Program Files\Racket-6.10.0.1\collects\racket\private\class-internal.rkt:3507:0: do-make-object > C:\Users\Leif Andersen\Documents\GitHub\video\video\private\video-canvas.rkt: [running body] > > However, when I switch the (require opengl) line to (require sgl/gl), it > now works. And I when I display the resulting version I get: > > 4.5.0 NVIDIA 382.05 > > This makes me think it is a problem with the opengl bindings in this > package, rather than a bug in the context created by Racket. > > — > You are receiving this because you are subscribed to this thread. > Reply to this email directly, view it on GitHub > <#20>, or mute the thread > <https://github.com/notifications/unsubscribe-auth/AAsR3ktvBtlSZMJfc7JD8YFh52htTqhqks5sUo3NgaJpZM4OtOxC> > . >

[LeifAndersen]

Sorry, my apologies:
"Hi Leif," of course.

No worries. :)

This is because you are getting a core context
(See https://www.khronos.org/opengl/wiki/Core_And_Compatibility_in_Contexts)

Interesting. In that case how would I get a compatibility context in Racket? (I was under the impression that Racket's OpenGL context in windows were always compatibility ones.)

[stephanh42]

Hi Leif, 2017-08-04 15:18 GMT+02:00 Leif Andersen <notifications@github.com>: Interesting. In that case how would I get a compatibility context in

Racket? (I was under the impression that Racket's OpenGL context in windows were always compatibility ones.)

I think you need to create an appropriate gl-config object and pass it to the canvas constructor: https://docs.racket-lang.org/draw/gl-config_.html (send <https://docs.racket-lang.org/reference/ivaraccess.html#%28form._%28%28lib._racket%2Fprivate%2Fclass-internal..rkt%29._send%29%29> a-gl-config set-legacy? <https://docs.racket-lang.org/draw/gl-config_.html#%28meth._%28%28%28lib._racket%2Fdraw..rkt%29._gl-config%7E25%29._set-legacy%7E3f%29%29> legacy?) → void? <https://docs.racket-lang.org/reference/void.html#%28def._%28%28quote._%7E23%7E25kernel%29._void%7E3f%29%29> I should however point out that an OpenGL driver is under no obligation to provide the legacy functionality. So it is possible that your driver does not support legacy profiles at all. Stephan

…

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[LeifAndersen]

AH, okay, that explains it. Thank you.

Basically, iirc, Racket's context default to compatibility, and you have to explicitly ask for core. And depending on your OS and drivers, it may still give you a compatibility one anyway. (Or at least try to).

Anyway, that makes sense. Do you have any recommendations on how one could go about making these opengl bindings work with core contexts?

[stephanh42]

Hi Leif, In retrospect I am now not even sure if the core/compatibilty context is indeed the issue. It may be that the function loading on Windows is incorrect. The page at https://www.khronos.org/opengl/wiki/Load_OpenGL_Functions says one needs to try GetProcAddress if wglGetProcAddress fails. (Frankly, some time ago I have decided for myself that the whole OpenGL API is completely insane and not worth my time. Case in point, this whole function loading madness. Why can't they just provide a normal .dll/.so/dylib with normal names like any other library in the world?) Stephan 2017-08-04 16:46 GMT+02:00 Leif Andersen <notifications@github.com>:

…

AH, okay, that explains it. Thank you. Basically, iirc, Racket's context default to compatibility, and you have to explicitly ask for core. And depending on your OS and drivers, it may still give you a compatibility one anyway. (Or at least try to). Anyway, that makes sense. Do you have any recommendations on how one could go about making these opengl bindings work with core contexts? — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#20 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAsR3mkYTYep1H9uaqnS9qGCzR_K0VBrks5sUy6vgaJpZM4OtOxC> .

[jeapostrophe]

When I saw the issue, I assumed it was the function loading problem too, but IIRC the opengl module already deals with this correctly. glGetString is available in the most recent OpenGL versions, so core/compat shouldn't matter: http://docs.gl/gl4/glGetString

[LeifAndersen]

True. And if it was just a context issue, I wouldn't expect the exact same code but using sgl/gl to work.

(Frankly, some time ago I have decided for myself that the whole OpenGL API is completely insane and not worth my time. Case in point, this whole function loading madness. Why can't they just provide a normal .dll/.so/dylib with normal names like any other library in the world?)

Ha, fair. Sadly I don't know of a better (portable) way to display a bunch of rgb24 pixels to the screen. Cairo kind of works, but ist much more limited in what it can display, and is also much slower. SDL would work, but you can only make an sdl context (so to speak), in a new window, which makes it hard to have non SDL gui elements in the same window.