Alembic: fixed refcount issue when duplicating imported objects

Duplicating an imported object didn't increment the cache reader's refcount,
whereas removing the duplicate did decrement it. This caused problems.

3 files changed, 8 insertions, 0 deletions

diff --git a/source/blender/alembic/ABC_alembic.h b/source/blender/alembic/ABC_alembic.h
index 6b698e5ec66..6228ae60c56 100644
--- a/source/blender/alembic/ABC_alembic.h
+++ b/source/blender/alembic/ABC_alembic.h
@@ -121,6 +121,7 @@ struct DerivedMesh *ABC_read_mesh(struct CacheReader *reader,
                                   const char **err_str,
                                   int flags);
 
+void CacheReader_incref(struct CacheReader *reader);
 void CacheReader_free(struct CacheReader *reader);
 
 struct CacheReader *CacheReader_open_alembic_object(struct AbcArchiveHandle *handle,
diff --git a/source/blender/alembic/intern/abc_object.cc b/source/blender/alembic/intern/abc_object.cc
index d2698da2cd3..94ec77f4191 100644
--- a/source/blender/alembic/intern/abc_object.cc
+++ b/source/blender/alembic/intern/abc_object.cc
@@ -370,4 +370,5 @@ void AbcObjectReader::incref()
 void AbcObjectReader::decref()
 {
 	--m_refcount;
+	BLI_assert(m_refcount >= 0);
 }
diff --git a/source/blender/alembic/intern/alembic_capi.cc b/source/blender/alembic/intern/alembic_capi.cc
index 15f3d1ff6ea..c9ce0d73e82 100644
--- a/source/blender/alembic/intern/alembic_capi.cc
+++ b/source/blender/alembic/intern/alembic_capi.cc
@@ -980,6 +980,12 @@ void CacheReader_free(CacheReader *reader)
 	}
 }
 
+void CacheReader_incref(CacheReader *reader)
+{
+	AbcObjectReader *abc_reader = reinterpret_cast<AbcObjectReader *>(reader);
+	abc_reader->incref();
+}
+
 CacheReader *CacheReader_open_alembic_object(AbcArchiveHandle *handle, CacheReader *reader, Object *object, const char *object_path)
 {
 	if (object_path[0] == '\0') {