Blender Git Loki

USD Import: remove usd_util files.

Moved the two create_reader() implementations from usd_util.(h|cc)
to static functions in UsdStageReader and removed the usd_util
files from the project.

USD Import: stage reader validation and cleanup.

Added USDStageReader validation and guard against null
stage in the USDStageReader destructor.

USD Import: remove UsdPrimReader stage member.

The UsdPrimReader class doesn't need a stage pointer as a
member because the stage can implicitly be accessed
through the prim itself, as long as the prim is valid.
I removed the UsdPrimReader::stage_ member and updated the
relevant constructors and function calls. Also, updated
the various readers to construct schemas directly from
the contained prim, e.g., pxr::UsdLuxRectLight rect_light(prim_)

USD Import: UsdPrimReader interface cleanup.

Removed empty add_cache_modifier() function and made
create_object() abstract.

USD Import: naming convention fix.

To be consistent with the convention used in the USD exporter,
updated class member variables to consistently use snake case
and trailing underscores instead of the m_ prefix.

USD Import: snake case for function names.

As part of code cleanup, now using snake case consistently
for class member function names, to match the convention
used in the USD exporter code.

USD Import: added blender::io::usd namespace.

Added blender::io::usd namespace where it was missing, to
conform to the convention used in the USD exporter code.

USD Import: removed unneeded include guards.

USD Import: use pragma once in headers.

Replaced include guards with pragma once directives,
to conform to the conventions used in the existing USD
export code.

USD Import: removed commented out code.

USD Import: removed WM_reportf() trace calls.

USD Import: import display colors.

Added support for reading the display color primvars. This
option is off by default in the mesh read flags.

USD Import: read attributes null data guard.

Checking for null pointer to avoid crash when custom data
allocation fails.

USD Import: removed printf call.

USD Import: crash on reading no polys.

Fixed a crash where polys were not being read for new meshes when
the MOD_MESHSEQ_READ_POLY flag isn't set. Crash occurs because
downstream code expects polys to exist. Modified the logic to
always read verts and polys for new meshes, regardless of the
value of the read flag.

USD Import: subdiv option default to off.

The Import Subdiv Option can sometimes behave unexpectedly,
losing all sharp edges. Turning this option off by default
until the behavior can be fine tuned.

USD Import: fixed compiler warnings.

USD Import: Light Intensity Scale option.

Added new float import option to scale intensity of imported
lights.

USD Import: fixed compiler warning.

USD Import: simplify xform matrix computation.

Updated the USDXformReader matrix computation function to use the
standard UsdGeomXformable API for querying the prim's local
transform and to determine whether the matrix is time-varying,
rather than explicitly iterating over the UsdGeomXformOps.