# 18 Frequently asked questions

1. VIEWMOL on Linux reports on start up:
   `viewmol: can't load library 'libMesaGLU.so.3'`
   or another library.
   VIEWMOL does not find a dynamical linked library it needs. The reason for this is that either the library is not installed, the wrong version is installed, or the dynamic linker is not set up to find this library. VIEWMOL needs the following dynamic libraries:

         libtiff.so.3
         libpng12.so.0
         libz.so.1
         libGLU.so.1
         libGL.so.1
         libXm.so.3
         libXmu.so.6
         libXp.so.6
         libXi.so.6
         libXext.so.6
         libXt.so.6
         libX11.so.6
         libpthread.so.0
         libutil.so.1
         libdl.so.2
         libm.so.6
         libc.so.6
         libjpeg.so.62
         libstdc++.so.5
         libgcc_s.so.1
         libGLcore.so.1
         libSM.so.6
         libICE.so.6
         /lib/ld-linux.so.2

   These libraries can normally be found in `/lib`, `/usr/lib`, and `/usr/X11R6/lib`. The dynamic linker checks the major version number and will refuse any library where the major version number does not match. The minor version number does not matter. The dynamic linker has to be set up to search the directories which contain these libraries. This is done in the file `/etc/ld.so.conf`. After modifying this file run `ldconfig -v` as root. Alternatively, the environment variable `LD_LIBRARY_PATH` can be set to point to these directories.
2. VIEWMOL on Linux reports on start up:
   `viewmol: Symbol 'jpeg_resync_to_restart' is not defined.`
   There are two different versions of `libtiff.so` distributed with different Linux distributions. One contains jpeg code (Debian) the other doesn't (RedHat). VIEWMOL has now been linked with the version which does not contain jpeg code so that this error will probably not occur anymore. If this error occurs only a recompilation will help. Please notify the maker of your Linux distribution so that they can make their distribution compatible.
3. When I try to recompile VIEWMOL I get a lot of error messages:

         cc -c -Wall -DLINUX -I/usr/compat/linux/usr/include/GL/
         -I/usr/compat/linux/usr/include/gr/ -O6 -m486
         -fomit-frame-pointer
         ../annotate.c
         ../annotate.c:19: X11/StringDefs.h: No such file or directory
         ../annotate.c:20: X11/cursorfont.h: No such file or directory
         ../annotate.c:21: Xm/Xm.h: No such file or directory
         ../annotate.c:22: Xm/Text.h: No such file or directory
         In file included from ../annotate.c:24:
         ../viewmol.h:20: X11/Intrinsic.h: No such file or directory
         ../viewmol.h:21: GL/gl.h: No such file or directory
         ../viewmol.h:22: GL/glx.h: No such file or directory
         *** Error code 1

   To recompile VIEWMOL you need to install the X Window System and OpenGL development environments which, in most Linux distributions, are separate packages. In this case you are missing all X Window System and OpenGL header files. You also need the development environment of lesstif or Motif for all header files in `/usr/include/Xm`.
4. While trying to recompile VIEWMOL the link step fails with:

         ld:
         Unresolved:  __eprintf

         *** Error code 1 (bu21)

   or a similar message referring to `__eprintf` (encountered on SGIs and IBMs so far only). There is a problem with the TIFF library you are linking with. If you have built the library yourself make sure it was built on the same machine as where you try to link VIEWMOL. If you have been trying to use a vendor supplied version of the TIFF library try to download and compile the library yourself.
5. Parts of one or more of VIEWMOL windows are not drawn while VIEWMOL runs on a Linux system with a Nvidia graphics card:
   Some of the Nvidia drivers have this problem if full-scene antialiasing is enabled. Set the environment variable `__GL_FSAA_MODE` to 0 before starting VIEWMOL to disable full-scene antialiasing and see if the problem disappers.