BRL-CAD bundles and maintains a number of external libraries and tools
critical to its functionality.

1.  Un-installed tools

lemon		http://www.hwaci.com/sw/lemon/			Parser generator, used by obj and step converters
perplex		BRL-CAD project					Tool to simplify creating re2c scanners, used by obj and step converters
re2c		http://re2c.org/				Scanner/lexer generator, used by obj and step converters
xmltools	http://xmlsoft.org/				Verify DocBook inputs and generate DocBook outputs

2.  Header-only libraries

Eigen		http://eigen.tuxfamily.org			Linear algebra - used by NURBS code
boost		http://www.boost.org				C++ utilties - used by libpc and obj converter
tnt		http://math.nist.gov/tnt/overview.html		Linear algebra - used by NURBS, plan is to replace with Eigen

3.  Installed libraries

clipper		http://www.angusj.com/delphi/clipper.php	Boolean clipping - intersection, union, difference & 
								exclusive-or - on 2D polygons.  Used by Archer GUI.
libpng		http://www.libpng.org/pub/png/libpng.html	Portable Network Graphics library, used extensively.
libregex	http://www.arglist.com/regex			Regular expression library.  It might be interesting to try something
								like re2  PCRE here - this libregex isn't really maintained and
	                                                        has a nasty habit of colliding with Tcl's regex and/or system regex
								functionality.  Used by the red command, as well as search in librt and
                	                                        src/conv/proe-g.c
libtermlib	early bsd termlib from vi			Used by burst and libcursor, possibly others - long term goal is to 
								move away from this API as it does not work on Windows (and neither 
								do any of the tools using it.)
libutahrle							Utah run length encoded format - used by image processing tools, (?)
libvds		http://vdslib.virginia.edu			View dependent simplification.  Used for MGED/Archer level of detail control
libz		http://zlib.net/				zlib data compression library. Used widely - png and openNURBS 
								requirement, etc.
openNURBS	http://www.opennurbs.org			Non-Uniform Rational B-Splines support in libbrep, librt
poly2tri	fork of git://github.com/jhasse/poly2tri.git,	poly2tri is a constrained Delaunay triangulation library, and is
		which was in turn based on 			used during NURBS tessellation.
		http://code.google.com/p/poly2tri/
step		http://stepcode.org				Derived from NIST STEP Class Libraries, with many modifications from
								BRL-CAD and other parts, this library supports STEP geometry conversion
tcl		http://www.tcl.tk/				Tool Command Language (TCL) - foundation of MGED's command language
tk		http://www.tcl.tk/				Graphical toolkit for Tk - currently used for most graphical BRL-CAD programs.

4.  Installed tools

URToolkit							These are tools that were part of the original UtahRLE distribution.  Traditionally
								we distribute them, but it's not clear if they are ever used in standard BRL-CAD workflows

5.  Tcl/Tk packages

hv3		http://tkhtml.tcl.tk/hv3.html			This is the full web browser in Tcl/Tk, not just the subset used by the MGED help system.
								The plan is to switch to using the full browser and its capabilities (like searching.)
incrTcl		http://incrtcl.sourceforge.net/			Object oriented extension for Tcl/Tk - all Archer GUI work uses these extensions
iwidgets	http://incrtcl.sourceforge.net/iwidgets		Part of the incrTcl project, used by Archer
sqlite3		http://www.sqlite.org/				Although sqlite has many potential uses, currently it's in place for hv3
tkhtml		fork of http://tkhtml.tcl.tk/tkhtml.html 	Used by MGED and Archer help systems now, and by hv3 once it is up and running.
tkpng		http://www.muonics.com/FreeStuff/TkPNG/ 	PNG photo image support for Tk - used by Archer
tktable		http://tktable.sourceforge.net/			High performing table widget for Tcl/Tk, used by Archer

6.  Misc
osl

