Blender Git Loki

Merged latest branch usd-importer-T81257-merge.

USD import: Update Prim Path Mask option help.

USDStageReader refactor.

Now passing the import params and settings as arguments
to the constructor, to reduce the number of arguments
required to invoke USDStageReader::collect_readers().
The constructor now takes a stage pointer as an argument,
to simplify error checking and initalization of the
import settings. Miscellaneous additional cleanup to
simplify the code.

USD Import: USDPrimReader comments.

Added comments regarding reference counting.

USD import: fixed Mesh reader initialization.

USDMeshReader::is_initial_load_ should be initialized to false,
to prevent forcing updates to verts and polys on every mesh
sequence read.

USD Import: add comments.

Organize USD and Alembic conditional includes.

Grouped common USD and Alembic mesh sequence cache code includes.

Update CacheFile comments.

Removed obsolete references to Alembic, as
the CacheFile code is now used for USD
archives as well.

USDVolumeReader improvements.

Fixed Volume reference counting error (incorrect
call to id_us_min()). Fixed error reading fieldName
attribute, which was incorrectly being read as a string
rather than a token. Avoiding use of auto and unneeded
declararions. Logically grouping related code. Now
invoking attribute Get() functions with the given time.

USD Import: remove variant selection mask.

Removed logic to process variant selection in
Prim Path Mask, as this code needs to be
extended to handle variants specified in child prims.
This functionality can be added back once it's
fully developed. Also, now printing warning message
if the Prim Path Mask doesn't specify a valid prim.

Rename USDStageReader prune functions.

Renamed USDStageReader prune_by_visibility()
and prune_by_purpose() member functions to
include_by_visibility() and include_by_purpse(),
respectively, to reflect the current semantics.
I.e., both functions are now answering the question,
'should the prim be included in the traversal',
returning true to include and false to exclude.

USDStageReader::prune_by_purpose() refactor.

Per suggestion by Sybren in his review, flipped the samanitcs
for prune_by_purpose() to return true=include and false=exclude.
Also simplified the conditional logic to reduce nesting.

USDStageReader::prune_by_visibility() refactor.

Per suggestion by Sybren in his review, flipped the samanitcs
for prune_by_visibility() to return true=include and false=exclude.
Also simplified the conditional logic to reduce nesting.

Refactor USDStageReader::create_reader() logic.

Simplified conditionals with early returns.

USD importer compile error fix.

USD importer naming convention fix.

Removed underscore prefix from static function name, as such
prefixes aren't used anywhere else in the USD I/O code.

Refactor USDStageReader pruning functions.

Added USDStageReader member functions for pruning
by visibility and purpose, to replace existing static
versions of these functions. This simplifies the code
as the member functions take fewer parameters.

USD Importer code cleanup.

Removed unneeded print statement. Calling empty() to
check for empty string.

Refactor USDStageReader::create_reader().

Added USDStageReader::create_reader() and
USDStageReader::create_reader_if_allowed() member
functions, to replace the static implementations of
these functions. This reduces the number of required
arguments when calling these functions and clarifies
the intent through more descriptive naming.

Remove USDStageReader::clear_readers() parameter.

Removed unused decref parameter.