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, 19 insertions, 2 deletions

diff --git a/source/blender/blenkernel/intern/constraint.c b/source/blender/blenkernel/intern/constraint.c
index 47df31e3a2c..022073b0f12 100644
--- a/source/blender/blenkernel/intern/constraint.c
+++ b/source/blender/blenkernel/intern/constraint.c
@@ -95,6 +95,10 @@
 #  include "ABC_alembic.h"
 #endif
 
+#ifdef WITH_USD
+#  include "usd.h"
+#endif
+
 /* ---------------------------------------------------------------------------- */
 /* Useful macros for testing various common flag combinations */
 
@@ -5403,7 +5407,7 @@ static void transformcache_id_looper(bConstraint *con, ConstraintIDFunc func, vo
 
 static void transformcache_evaluate(bConstraint *con, bConstraintOb *cob, ListBase *targets)
 {
-#ifdef WITH_ALEMBIC
+#if defined(WITH_ALEMBIC) || defined(WITH_USD)
   bTransformCacheConstraint *data = con->data;
   Scene *scene = cob->scene;
 
@@ -5421,7 +5425,20 @@ static void transformcache_evaluate(bConstraint *con, bConstraintOb *cob, ListBa
     BKE_cachefile_reader_open(cache_file, &data->reader, cob->ob, data->object_path);
   }
 
-  ABC_get_transform(data->reader, cob->matrix, time, cache_file->scale);
+  switch (cache_file->type) {
+    case CACHEFILE_TYPE_ALEMBIC:
+#  ifdef WITH_ALEMBIC
+      ABC_get_transform(data->reader, cob->matrix, time, cache_file->scale);
+#  endif
+      break;
+    case CACHEFILE_TYPE_USD:
+#  ifdef WITH_USD
+      USD_get_transform(data->reader, cob->matrix, time * FPS, cache_file->scale);
+#  endif
+      break;
+    case CACHE_FILE_TYPE_INVALID:
+      break;
+  }
 #else
   UNUSED_VARS(con, cob);
 #endif