From: Michal Suchanek <hramrach@...>
Date: 2010-01-15T15:40:28+09:00
Subject: Re: 3D with Ruby (Ogre ?)

2010/1/15 Michael Brooks <michael.brooks@shaw.ca>:
> Hello Michal:
>
>> "Michal Suchanek" <hramrach@centrum.cz> wrote:
>>>
>>> I used the the gears.rb as the basis for a OpenGL programmable shader
>>> (i.e.
>>> GLSL) version of the gears program. The intro to it and download can be
>>> found through here:
>>>
>>> http://osdir.com/ml/ruby-talk/2009-03/msg00749.html
>>>
>> FWIW this does nt work for me on Linux.
>>
>> $ ruby gears_using_shaders.rb
>> Error - The program has terminated because the environment does not
>
> s>upport OpenGL 2.0 or greater GLSL shaders.
>>
>> $ glxinfo
>> name of display: :0.0
>> display: :0  screen: 0
>> direct rendering: Yes
>> server glx vendor string: SGI
>> server glx version string: 1.2
>> OpenGL vendor string: DRI R300 Project
>> OpenGL renderer string: Mesa DRI R300 (RV515 7153) 20090101  TCL
>> OpenGL version string: 1.5 Mesa 7.6.1
>
> I implemented the OpenGL 2.0 or greater version of the shader functions so
> you'll likely need to install OpenGL 2.0 or greater drivers for your video
> card.  It looks like you're running the software-only OpenGL drivers that
> come with Linux.

direct rendering: Yes

It isn't software only but they don't seem to support OpenGL 2.

>
> In the initialize procedure I do the following check for the required OpenGL
> functions:
>
>   # Exit if the environment can't handle the OpenGL 2.0 style
>   # GLSL shader api commands
>   if not (GL.respond_to?('CreateProgram') and
>           GL.respond_to?('CreateShader') and
>           GL.respond_to?('ShaderSource') and
>           GL.respond_to?('CompileShader') and
>           GL.respond_to?('AttachShader') and
>           GL.respond_to?('LinkProgram') and
>           GL.respond_to?('DeleteShader') and
>           GL.respond_to?('DeleteProgram'))
>     puts('Error - The program has terminated because the environment does '
> +
>          'not support OpenGL 2.0 or greater GLSL shaders.')
>     exit
>   end
>
> In theory, if your MESA / SGI driver supported shaders through ARB
> extensions (like some earlier OpenGL's did) instead of as built in functions

Yes, there are some ARB extensions listed.

> (like OpenGL 2.0+ in the recent ATI, Nvidia and Intel drivers) then you

The problem is that Intel does not do special driver for Linux, their
hardware is supposedly supported by X11/Mesa and the proprietary
drivers for ATI/nVidia cards simply don't work (tried with recent
cards about half an year ago).

> could modify this section and other sections of code to use the alternate

Running a demo is as far as I got in using OpenGL so I guess I will
pass on this for now.

> (i.e. older) function names.  However, I don't believe your drivers support
> shaders at all.
>

It supports fragment and vertex programs. I don't know it that's
sufficient but I think FireGL V3350 should support some shading.

Thanks

Michal