Also renamed AbcObjectReader::readObjectMatrix to
setupObjectTransform, as it does more than just reading the object
matrix; it also sets up an object constraint if the Alembic Xform is
animated.
Alembic is an interchange and caching format, that can contain custom
object schemas. Blender shouldn't crash (because of failing asserts) just
because it doesn't know such an object type.
It's a mapping from full path of an Alembic object to an AbcObjectReader*.
The fact that at some point it is used to construct parent-child relations
doesn't matter.
The importer was guessing whether an Alembic IXform object was part of a
child object, or should be represented as an Empty in Blender. By reversing
the order in which objects are visited, the children can now claim their
parent as part of the same object (so IPolyMesh claims its parent IXform
as part of the same Blender object). This results in much less guesswork.
I've also removed similar guesswork from the code that sets parent pointers,
by simply searching for the parent in a hierarchical way, instead of trying
to predict (again) which IXforms were turned into empties.
Also, visit_object() now actually visits the object -- previously it only
visited its children, and assumed the object it was called on was already
handled by a previous call.
create_transform_matrix(float[4][4]) did mostly the same as
create_transform_matrix(Object *, float[4][4]), but more elegant.
However, the former has some inconsistencies with the latter (which
are now merged and made explicit, turned out one was for z-up→y-up
while the other was for y-up→z-up), and was renamed to
copy_m44_axis_swap(...) to convey its purpose more clearly.
Furthermore, "loc" has been renamed to "trans", as matrices don't
store locations but translations; and more variables now have a src_
or dst_ prefix to denote whether they contain a matrix/vector in the
source or destination axis orientation.
AbcExporter::createTransformWriter() tries to predict the parent Xform
name, but if it cannot be found has multiple ways of creating it, possibly
under a different name than originally searched for.
See intern/gawain for the API change. Other files are updated to use the new name. Also updated every call site to the recommended style:
unsigned int foo = VertexFormat_add_attrib(format, "foo", COMP_ ... )
