Read the problem description below, but here's what it means to you
building on SGI IRIX.  

     You probably already knew you couldn't mix GNU C++ and MIPSPro CC C++
object files in an application due to different name mangling schemes,
right?

     In other words, C++ dependencies (osg, sdts++, etc.) must be built
with the same compiler you build your apps with (g++ or CC).  NOTE: THIS
ALSO INCLUDES THE OPENGL "GLU" LIBRARY!  The native IRIX libGLU is
C++ dependent, and of course CC-compatible (NOT g++ compatible).

     So what does this mean?  If you build VTerrain and all it's C++
dependencies using:

     1) GCC, then you must build your own libGLU library using GCC and link
        to it.

   or alternatively...:

     2) MIPSPro CC, then you must compile with -mips3 or -mips4 on the CC
        command-line (to enable RTTI compilation).

     Both are easy, once you know, but option 2 is easier.  

     For option 1, just grab Mesa (www.mesa3d.org), build --enable-static,
grab the libGLU.a library file and stash it somewhere, and then when
building GLU client apps, replace -lGLU in link lines with a path to your
Mesa-built libGLU.a file.  The top-level Make.defs variables support this.

     For option 2, just tweak your CC and CXX makefile macros to contain
-mips3 or -mips4 to enable RTTI (needed by VTerrain and some of its C++
dependencies).  Again, the top-level Make.defs file supports this.  Just tweak
the line comments.

------------------------------------------------------------------------------

SITUATION:  Compiling IRIX apps with GCC which combine C++ and OpenGL code

PROBLEM:    All compiled apps core dump deep down in ios::init before you
            even get to main()

SYMPTOM:    > ./tst
            Segmentation fault (core dumped)

            > dbx ./tst
            (dbx) where
            >  0 ios::init
            ...

REASON:     Your apps are linked (indirectly) to both to libC.so (IRIX C++) 
            "and" libstdc++ (GNU C++).  This is a big no-no.

            HOW?: G++ apps implicitly must link to libstdc++, and libGLU.so
            on IRIX depends on libC.so (see "elfdump -Dl libGLU.so")

SOLUTIONS:  1) Compile your own libGLU with GCC and link to it.

                 Building a static libGLU.a from Mesa 3.4.1 worked for me.
                 Just build for the same ABI and appropriate architecture.
                 Then replace your -lGLU link references with a path to the
                 libGLU.a file.

            2) Alternatively, use MIPSPro CC for all C++ code.

                 NOTE: if your code requires RTTI (ANSI casts:
                 dynamic_cast, typeid, etc.), MIPSProCC will not build it
                 by default, and how to "make" it build is undocumented: an
                 explicit -mips3 or -mips4 on the CC command-line triggers it.

                 ...NOTE: having a default ABI of mips3 or mips4 in your
                 $COMPILER_DEFAULTS_PATH will not kick on the RTTI-is-ok
                 flag in CC.  Despite what the SGI docs say, default ABI
                 mips3/mips4 is not equivalent to putting -mips3/-mips4 on
                 the command line.  [scratch,scratch] Beats me...