glewCreateContext fails on MacOSX on Travis

[wchristian]

Right now the tests only skip and mention they failed. They don't try to inspect the return values to see why they failed. Tests should try and give more feedback about that.

[wchristian]

GLenum err = glewInit();
if (GLEW_OK != err)
{
  /* Problem: glewInit failed, something is seriously wrong. */
  fprintf(stderr, "Error: %s\n", glewGetErrorString(err));
  ...
}

[wchristian]

This is also misleading:

skip "glewInit not successful, skipping tests", 2 if glewCreateContext() or glewInit(); # GLEW_OK == 0

Should be separate lines. Also i'm curious to see if glewInit gives useful feedback if it's called before glewCreateContext. Maybe try this in a separate branch.

[wchristian]

Where did the idea to use glewCreateContext come from anyhow? As far as i can see it is only declared for glewinfo, which is a specific commandline tool.

[devel-chm]

The line-by-line check for the glewCreateContext and glewInit are in test 01context.t The usage in 02* etc is for skipping runtime tests if real contexts are not available. I think Max used this approach first but it is is good in the sense of being lightweight.

[wchristian]

Alright, so neither of us knows why it's there. Checking to see if it's actually necessary.

As for 02, the line is misleading as it only says glewInit in the skip message, it should at least mention both, i think?

[wchristian]

Err, results on this:

If i don't run glewCreateContext (using master) it crashes as soon as it tries to use a GL function:

glGenBuffers not available on this machine at C:/strawberry/perl/site/lib/OpenGL/Modern/Helpers.pm line 267.

If i don't run glewInit, Microidium works, but runs at 3.6 fps?

[wchristian]

Ok, on further inspection, without create context glewinit errors out with "Missing GL version" if glCreateContext wasn't called.

Do you think you can get some more details out of glCreateContext if it fails? Maybe by making some of the internally called functions available in Perl? ( https://github.com/nigels-com/glew/blob/master/auto/src/glewinfo_tail.c#L176-L598 )

[devel-chm]

I thought you were asking about why glewCreateContext specifically. In order for GLEW to load the needed extensions, there has to be an OpenGL context. glewCreateContext is good because it comes with the GLEW distribution.

[wchristian]

Alright, so if that's not strictly necessary, can you throw together a different context creation process we can bash against mac?

[devel-chm]

You can use GLUT from OpenGL. Once the window+context is created, you can call glewInit. If you use the just fixed for the transparent glewInit calls, it should just work. (Famous last words...)

[wchristian]

Right, so you probably want to add -framework GLUT to MFpl so it can link and then special-case macosx in the test. Also, i'm asking you to write the test code because you know better what you're doing there. :x

[devel-chm]

That is the problem. If the MacOSX code built and linked correctly, then glewCreateContext should work as well. I put out a call for someone with MacOSX to help debug. Here's hoping....

--Chris

[devel-chm]

Oh, I didn't realize this was in the Travis-CI thread. There is definitely something needed to allow glutCreateContext to work. I vaguely recall something about Xvfb or some such from a search... HTH.

[wchristian]

If i understand this correctly, xvfb won't run on osx anymore without considerable effort to get quartz installed and set up:

http://stackoverflow.com/questions/25451133/xvfb-run-on-os-x/32786365#32786365

Please read and tell me what you get from it.

[wchristian]

Ok, turns out there is xvfb on those machines:

https://github.com/travis-ci/travis-ci/issues/2351#issuecomment-49422274

And i actually got somewhat close to making things happen, but now i'm quite stuck:

$ if [ "${TRAVIS_OS_NAME}" = "osx" ]; then Xvfb :99 -ac -screen 0 1024x768x8 -extension GLX; fi
[mi] Extension "GLX" is not recognized
[mi] Only the following extensions can be run-time disabled:
[mi]    Generic Events
[mi]    Composite
[mi]    DAMAGE
[mi]    DOUBLE-BUFFER
[mi]    DPMS
[mi]    MIT-SCREEN-SAVER
[mi]    MIT-SHM
[mi]    RANDR
[mi]    RENDER
[mi]    X-Resource
[mi]    XFIXES
[mi]    XINERAMA
[mi]    XTEST
[mi]    XVideo
_XSERVTransmkdir: ERROR: euid != 0,directory /tmp/.X11-unix will not be created.
_XSERVTransSocketUNIXCreateListener: mkdir(/tmp/.X11-unix) failed, errno = 2
_XSERVTransMakeAllCOTSServerListeners: failed to create listener for local
(EE) 
Fatal server error:
(EE) Cannot establish any listening sockets - Make sure an X server isn't already running(EE) 
The command "if [ "${TRAVIS_OS_NAME}" = "osx" ]; then Xvfb :99 -ac -screen 0 1024x768x8 -extension GLX; fi" failed and exited with 1 during .

[wchristian]

Asked in the Travis issues: https://github.com/travis-ci/travis-ci/issues/7313