With this, we are able to get rid of all the increasingly broken file
system utility code, and trust boost::filesystem to handle all the
cross-platform complexity.
The first version of this PR centred around C++17 & std::filesystem,
but support remains too elusive; it seems works out of the box in
Visual Studio (especially 2019), but is entirely missing from the Mac
dclang, and even with GCC 8.0 it requires an explicit '-l c++fs'.
Luckily the std:: version is almost exactly the boost:: version (not
surprising) so when the world's caught up, we can ditch Boost and go
all stdlib.
Setting up Conan requires a bit of work; we'll want to document the
details in the README.
At the end of the various material/mesh transformations we do, we were still using a ridiculously simplistic method of mapping RawMaterial to glTF MaterialData.
This switches to using FBX's GetUniqueID(), which should be the law of the land in general. Other model entities may need further investigation as well.
Looks like I never did the required cleanup after my accidental commit back in August.
This deletes the materials classes that were obsoleted back then, and comments out the
large swathes of PhysicalMaterial code that's not currently doing anything (i.e. all the
materials properties that glTF can't currently represent.)
This finishes the first phase of the FBX2glTF refactor, breaking utility classes out where things were getting too monolithic.
There is an equally important cleanup phase coming where we wrench all the various parts of this code, including the historical ones that we've rarely touched as yet, into a single C++ style paradigm, and modernise everything to C++11 at least.
But for now, we're just picking the pieces back on the floor so we can push 0.9.6 out. It's been far too long since a release.
Did not mean to commit/push the current state of master. But rather than
mess up source control history with a force push, I'll just try to hurry
to a stable point.