[HOpenGL] problems running SmoothOpenGL3

[Sven Panne]

Am Freitag, 31. Juli 2009 17:25:45 schrieb Michael [Plouj] Ploujnikov:
> [...] Finally, this is what I get if I try to compile with 'ghc --make':
>
> $ ghc --make -lglut SmoothOpenGL3.hs # the linker fails without -lglut
> similar to this:
> http://www.haskell.org/pipermail/hopengl/2008-September/000756.html

I don't know what's going on here, things work for me without -lglut on 
openSUSE 11.1. Which OS/distro are you using? It is hard to debug without 
actually seeing it fail for oneself. Anyway, I am in the process of changing 
the GLUT package to use dynamic linking internally, too, and the autoconf 
dependency will be removed as well. If you like, you could give the code on 
http://darcs.haskell.org/packages/GLUT/ a try and tell us about your results. 
Hopefully such linking issues will be a thing of the past... (famous last 
words ;-)

> [1 of 1] Compiling Main             ( SmoothOpenGL3.hs, SmoothOpenGL3.o )
> Linking SmoothOpenGL3 ...
> $ ./SmoothOpenGL3
> SmoothOpenGL3: user error (unknown GLUT call glutInitContextVersion,
> check for freeglut)

That's OK: To create an OpenGL 3.x context, you need a recent version of 
freeglut. Classic GLUT and older versions of freeglut simply do not have the 
API entries glutInitContextVersion and glutInitContextFlags. I really, really 
hope that the freeglut project admins make a release soon. I am active in this 
project, but I can't make releases. There are a few GL/GLX extensions I'd like 
to add to freeglut, too, but only after a release.

Depending on your OpenGL driver, you can make things work by using

    ./SmoothOpenGL3 classic

This will create a "normal" (i.e. legacy) context, which might work, too. 
Perhaps you have to change the GLSL "#version 140" to "#version 130", your 
mileage may vary, but this is a driver issue, and OpenGL 3.1 is really still 
on the bleeding edge. NVIDIA's 190.18 drivers work fine for me on openSUSE 
x86_64. Note that SmoothOpenGL3 is perhaps not the most elegant way to use 
OpenGL 3.x, it is my first shot at a "pure" OpenGL 3.1 program which does not 
use any deprecated functionality, only shaders, vertex arrays in buffer 
objects, hand-calculated matrices, etc. From this example one can see that the 
OpenGL package misses a Haskell representation of the various GLSL matrix 
types, but that is a topic for a different mail thread. :-)

Cheers,
   S.