Blender Git Commits

USD: use LISTBASE_FOREACH

No functional changes.

USD: renamed 'xform' to 'transform'

Sergey and I don't agree on 'tfm' vs. 'xform', so I just chose to not to
use either and avoid abbreviating altogether.

USD: moved all code into C++ namespace 'USD'

USD: clarified comment about defining _GLIBCXX_PERMIT_BACKWARD_HASH

USD: Fix exporting of meshes of dupli-objects

The dupliobject's `base_flag` variable needed to be copied from its
duplicator.

Cleanup: USD: clarified a comment

USD: pass data from invoke() to execute() in a struct

This makes the code somewhat more complex, but more explicit and
future-proof as well.

USD: properly mark unused variable

USD: Store BKE_main_blendfile_path(bmain) in a variable

USD: no more fatal message in FindUSD.cmake

Instead of breaking the build, it properly sets `USD_FOUND` to `FALSE`.

USD: added note about upstream pull request for PXR_BUILD_USD_TOOLS

USD: Avoid potential conflict with 2nd USD library

We now build the USD library with
`-DPXR_SET_INTERNAL_NAMESPACE=usdBlender`, which replaces the default
namespace `pxrInternal_v_x_y` with `usdBlender`. This is a preventative
measure that avoids possible conflicts when add-ons try to load another
USD library into the same process space.

USD: install libusd_m.a from usd.cmake instead of from harvesting step

USD: remove `PXR_PLUGINPATH_NAME` when testing

USD: patch USD to allow Blender to construct a path to JSON files

USD requires some JSON files, and it uses a static constructor to
determine the possible filesystem paths to find those files. This made
it impossible for Blender to pass a path to the USD library at runtime,
as the constructor would run before Blender's main() function. We have
patched USD (see usd.diff) to avoid that particular static constructor,
and have an initialisation function instead.

USD: Fixed export of animated meshes

I missed a bit earlier, when creating the mesh attributes with an explicit
default, causing meshes to be non-animated. Now I use the 'sparse value
writer', as recommended on the USD forum [1], and animated meshes are
properly written once again.

[1] https://groups.google.com/d/msg/usd-interest/cVJv_eDYxZo/oREDDm11AgAJ

USD: Support '.usd' as export extension (thanks @superfunc) and proper filtering in the file browser

USD: Allow running unit tests without 'make install' step

When the PXR_PLUGINPATH_NAME environment variable is defined, the USD
library uses it to find its JSON files. This allows the unit tests to
run without having to 'make install' Blender.

USD: Fixed include path for unit tests, now TBB headers can be found

USD: fixed paths in usd.diff

I made the previous diff with `git diff` in the USD source, which produced
paths incompatible with the patch command we use to apply it.