[Octave-bug-tracker] [bug #44478] test __osmesa_print__.cc-tst crashes with Nvidia drivers

[Dan Sebald]

Follow-up Comment #104, bug #44478 (project octave):

Mixing functions is obviously what's going on.  But I still don't know what to
make of the description of how OpenGL operates:

https://www.opengl.org/wiki/Load_OpenGL_Functions
https://www.opengl.org/wiki/Creating_an_OpenGL_Context_%28WGL%29

The vague descriptions of how to initialize OpenGL suggest to me that the
OpenGL functions shouldn't exist until a context is created.  Perhaps the
loading of functions that is referred to is the OpenGL extensions only.

What Brian has written suggests that no matter the intended OpenGL
initialization, something special is going on with Mesa/OSMesa that allows
their OpenGL routines to "morph".

What Rik has said is what I've been trying to suggest and attempting to do. 
Also, Brian in that quote says as well: "If you want to do offscreen rendering

with a hardware GPU, the easiest approach is to use framebuffer objects." 
I've been trying to make framebuffer work with the nVidia driver.  From what
I'm reading, I should be able to used framebuffer as an OpenGL extension, and
that something like GLEW is needed to make that framebuffer support available.
 So, the approach, I think, is to query the current OpenGL somehow to see if
it has a framebuffer extension function--if so, then use the framebuffer for
offscreen rendering--if not, then call OSMesaCreateContext and hope that -lGL
is the Mesa OpenGL environment.  And that approach suggests we should never
have the -lOSMesa -lGL order of linking otherwise we wouldn't be able to get
at the other vendor's OpenGL extensions.

In all, it seems like a lot of work for what is ultimately a bitmap converted
to some other graphics format using an external program.


    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?44478>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/