USD: add USD importer

This is an initial implementation of a USD importer.

This work is comprised of Tangent Animation's open source USD importer,
combined with features @makowalski had implemented.

The design is very similar to the approach taken in the Alembic
importer. The core functionality resides in a collection of "reader"
classes, each of which is responsible for converting an instance of a
USD prim to the corresponding Blender Object representation.

The flow of control for the conversion can be followed in the
`import_startjob()` and `import_endjob()` functions in `usd_capi.cc`.
The `USDStageReader` class is responsible for traversing the USD stage
and instantiating the appropriate readers.

Reviewed By: sybren, HooglyBoogly

Differential Revision: https://developer.blender.org/D10700

1 files changed, 8 insertions, 9 deletions

diff --git a/source/blender/io/alembic/ABC_alembic.h b/source/blender/io/alembic/ABC_alembic.h
index 3d1391ac2a4..0dbebb1e4c4 100644
--- a/source/blender/io/alembic/ABC_alembic.h
+++ b/source/blender/io/alembic/ABC_alembic.h
@@ -25,6 +25,7 @@
 extern "C" {
 #endif
 
+struct CacheArchiveHandle;
 struct CacheReader;
 struct ListBase;
 struct Main;
@@ -33,8 +34,6 @@ struct Object;
 struct Scene;
 struct bContext;
 
-typedef struct AbcArchiveHandle AbcArchiveHandle;
-
 int ABC_get_version(void);
 
 struct AlembicExportParams {
@@ -100,11 +99,11 @@ bool ABC_import(struct bContext *C,
                 bool validate_meshes,
                 bool as_background_job);
 
-AbcArchiveHandle *ABC_create_handle(struct Main *bmain,
-                                    const char *filename,
-                                    struct ListBase *object_paths);
+struct CacheArchiveHandle *ABC_create_handle(struct Main *bmain,
+                                             const char *filename,
+                                             struct ListBase *object_paths);
 
-void ABC_free_handle(AbcArchiveHandle *handle);
+void ABC_free_handle(struct CacheArchiveHandle *handle);
 
 void ABC_get_transform(struct CacheReader *reader,
                        float r_mat_world[4][4],
@@ -125,10 +124,10 @@ bool ABC_mesh_topology_changed(struct CacheReader *reader,
                                const float time,
                                const char **err_str);
 
-void CacheReader_incref(struct CacheReader *reader);
-void CacheReader_free(struct CacheReader *reader);
+void ABC_CacheReader_incref(struct CacheReader *reader);
+void ABC_CacheReader_free(struct CacheReader *reader);
 
-struct CacheReader *CacheReader_open_alembic_object(struct AbcArchiveHandle *handle,
+struct CacheReader *CacheReader_open_alembic_object(struct CacheArchiveHandle *handle,
                                                     struct CacheReader *reader,
                                                     struct Object *object,
                                                     const char *object_path);