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Troubleshooting

RSI cannot control driver quality, so you may have trouble with some drivers that might be buggy. Besides obtaining a driver update from the vendor, there are several things you can do to make IDL usable again in the presence of a buggy driver:

* Read the documentation that came along with your driver software carefully. There may be a number of diagnostic tools or environment variables that you can set to provide some relief.

* When using an X server based on XFree86, modifying the XFree86 configuration file may solve any problems. Consult the XFree86 documentation for details. Also, the XFree86 server startup log, usually found in /var/log, can provide many clues about the problem.

* Set the LIBGL_ALWAYS_INDIRECT environment variable. This causes OpenGL to ignore IDL's request to use direct rendering and would then avoid any bugs that may exist in the direct path.

* Configure your IDL session to use software rendering when required or code your IDL application to use software rendering. These details are covered in IDL documentation.

* As a last resort, remove/rename the gl_driver shared library from your IDL installation (in the binary directory). This will keep IDL from attempting to use direct or indirect hardware rendering. IDL will instead perform all rendering itself and send the results to the X server with "2D" commands.

* One expert IDL programmer reported in March 2004 on the IDL Newsgroup this promising workaround on a host running Fedora Linux:

"If you're a user of a recent Linux (like Fedora), and you've experienced IDL crashes that post the following fatal error:

Floating exception

when attempting to use any of IDL's OpenGL 3D stuff (like the Demo->Itools, for example), you might try the following:

setenv MESA_NO_ASM 1

This disables some specific ASM code in the Mesa library which was causing these types of crashes for me. I use an ATI Radeon 7500 plus XFree86 4.3.0's Radeon drivers. With this environment variable set, IDL's 3D hardware rendering seems stable, and definitely executes much faster than the alternative software rendering option."