Problem with OpenGL and ATI HD3850

[Roland Smith]

On Wed, Apr 29, 2009 at 04:41:13PM +0200, Oliver Lehmann wrote:
> Hi,
> 
> I must admit that I'm not that familiar with the topic, but anyhow:
> 
> I'm trying to get an application to run which is called "freeorion". It
> uses as a backend GiGi which itself uses Ogre3D. Inside Ogre3D, the GL
> Renderer is used for rendering (Not SDL for example). When I now startup
> the application, All I get is
> 
> unknown chip id 0x9515, can't guess.
> main() caught exception(std::exception): basic_string::_S_construct NULL
> not valid
> 
> The exception is caused because glGetString(GL_VERSION) returns NULL
> which is assigned afterwards.
> 
> The "unknown chip id..." comes out of dri from the radeon driver.
> 
> It is clear to me, that there is no hardware 3D support for my card.
> This is not the point.
> 
> I wonder why the GL is moving to the radeon driver. Shouldn't DRI support
> a software 3D emulation which should be used if there is no hardware
> support?

It is, see below.
 
> Executing glxgears for example says
> 
> olivleh1 at kartoffel olivleh1> glxgears -info
> unknown chip id 0x9515, can't guess.
> GL_RENDERER   = Software Rasterizer
> GL_VERSION    = 2.1 Mesa 7.4
> GL_VENDOR     = Mesa Project

Mesa is the fallback software renderer.

> So GL_VERSION seems to be indeed something - So I wonder what could cause
> the NULL exception here....
> 
> In Ogre3D, the failing code part is:
> 
>     void GLSupport::initialiseExtensions(void)
>     {
>         // Set version string
>         const GLubyte* pcVer = glGetString(GL_VERSION);
> printf("ogre 110\n");
>         assert(pcVer && "Problems getting GL version string using
> glGetString"); printf("ogre 110.1\n");

The assert is weird. Why take an AND of pcVer and a string? Since the
string is a constant non-null value, using the standard && operator is useless. 
Is the && operator overloaded by any chance? That could cause the trouble.

Roland
-- 
R.F.Smith                                   http://www.xs4all.nl/~rsmith/
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