LLConvexDecomposition is a library used to decompose triangle meshes
into convex components.  It is based on Havok(TM) physics libraries.
The source for the library itself is public but the havok library is
not. Linden Lab also shares the code for LLConvexDecompositionStub, a
stub version of the same library with no proprietary components.

Building/Using this code:

LLConvexDecomposition will fail to build for external developers,
because the havok library it depends on cannot be fetched.  You should
be able to build the stub library, which has no dependencies.  The
source for the non-stub library is included to illustrate how we use
havok's capabilities to do convex decomposition; if you want to
implement an open-source llconvexdecomposition using another library,
you can start with the stub library and fill in the missing functions.