This is a standalone program to convert rigged models into simple, easy-to-parse formats. The only dependency is ASSIMP.
Install ASSIMP
On a Mac: brew install assimp
On a Mac or other Unix platform:
c++ -std=c++11 converter.cpp -o converter -I/usr/local/include -L/usr/local/lib -lassimp -g -Wall
Example (test refers to ASSIMP's test mesh directory):
./converter test/models-nonbsd/MD5/Bob.md5mesh Bob.obj
This will save the mesh to Bob.obj and the rig as Bob.tgf (bones) and Bob.dmat (skin weights).
You can use any input and output extensions that ASSIMP supports.
TGF and DMAT are pretty trivial formats for the skeleton bones and skin weights: http://libigl.github.io/libigl/file-formats/
You can load them with libigl::readTGF() and libigl::readDMAT() or write your own parser.
Note that the skin weights will be saved flattened, one per each vertex of each face, rather than one per vertex. This may change in a future update.
NOTE: If you want triangulated output, change the second parameter to aiImportFile from 0 to aiProcess_Triangulate. You can also use ASSIMP's built-in assimp command-line program to convert the mesh (and only use the rig from this project): assimp export input.whatever output.whatever -tri.
Public Domain CC0