Alembic: integrate cache file into the dependency graph

* The cache file datablock is now evaluated as part of the dependency graph,
  creating/freeing the Alembic file handle matching the current frame.
  Modifiers and constraints depend on this evaluation.
* Cache file handles and readers now only exist on COW datablocks, never the
  original ones.
* Object data paths are flushed back to the original for the user interface.
* The cache file keeps a list of all readers associated with its handle, and
  automatically frees them when the handle is freed. This kind of sharing of
  data across datablocks is weak but we have no better mechanism for it.

Fix T62720: Alembic sequences not working and crashing

Differential Revision: https://developer.blender.org/D4774

3 files changed, 5 insertions, 66 deletions

diff --git a/source/blender/makesrna/intern/rna_cachefile.c b/source/blender/makesrna/intern/rna_cachefile.c
index fb61be69ee6..189a4a7de86 100644
--- a/source/blender/makesrna/intern/rna_cachefile.c
+++ b/source/blender/makesrna/intern/rna_cachefile.c
@@ -45,29 +45,12 @@
 #    include "../../../alembic/ABC_alembic.h"
 #  endif
 
-static void rna_CacheFile_update(Main *bmain, Scene *scene, PointerRNA *ptr)
+static void rna_CacheFile_update(Main *UNUSED(bmain), Scene *UNUSED(scene), PointerRNA *ptr)
 {
   CacheFile *cache_file = (CacheFile *)ptr->data;
 
-  DEG_id_tag_update(&cache_file->id, 0);
+  DEG_id_tag_update(&cache_file->id, ID_RECALC_COPY_ON_WRITE);
   WM_main_add_notifier(NC_OBJECT | ND_DRAW, NULL);
-
-  UNUSED_VARS(bmain, scene);
-}
-
-static void rna_CacheFile_update_handle(Main *bmain, Scene *scene, PointerRNA *ptr)
-{
-  CacheFile *cache_file = ptr->data;
-
-  if ((cache_file->flag & CACHEFILE_DIRTY) != 0) {
-    BKE_cachefile_clean(bmain, cache_file);
-    BLI_freelistN(&cache_file->object_paths);
-    cache_file->flag &= ~CACHEFILE_DIRTY;
-  }
-
-  BKE_cachefile_reload(bmain, cache_file);
-
-  rna_CacheFile_update(bmain, scene, ptr);
 }
 
 static void rna_CacheFile_object_paths_begin(CollectionPropertyIterator *iter, PointerRNA *ptr)
@@ -76,20 +59,6 @@ static void rna_CacheFile_object_paths_begin(CollectionPropertyIterator *iter, P
   rna_iterator_listbase_begin(iter, &cache_file->object_paths, NULL);
 }
 
-static void rna_CacheFile_filename_set(PointerRNA *ptr, const char *value)
-{
-  CacheFile *cache_file = ptr->data;
-
-  if (STREQ(cache_file->filepath, value)) {
-    return;
-  }
-
-  /* Different file is opened, close all readers. */
-  cache_file->flag |= CACHEFILE_DIRTY;
-
-  BLI_strncpy(cache_file->filepath, value, sizeof(cache_file->filepath));
-}
-
 #else
 
 /* cachefile.object_paths */
@@ -122,9 +91,8 @@ static void rna_def_cachefile(BlenderRNA *brna)
   RNA_def_struct_ui_icon(srna, ICON_FILE);
 
   PropertyRNA *prop = RNA_def_property(srna, "filepath", PROP_STRING, PROP_FILEPATH);
-  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_CacheFile_filename_set");
   RNA_def_property_ui_text(prop, "File Path", "Path to external displacements file");
-  RNA_def_property_update(prop, 0, "rna_CacheFile_update_handle");
+  RNA_def_property_update(prop, 0, "rna_CacheFile_update");
 
   prop = RNA_def_property(srna, "is_sequence", PROP_BOOLEAN, PROP_NONE);
   RNA_def_property_ui_text(
diff --git a/source/blender/makesrna/intern/rna_constraint.c b/source/blender/makesrna/intern/rna_constraint.c
index 44445181402..c1c235d497b 100644
--- a/source/blender/makesrna/intern/rna_constraint.c
+++ b/source/blender/makesrna/intern/rna_constraint.c
@@ -729,22 +729,6 @@ static void rna_Constraint_objectSolver_camera_set(PointerRNA *ptr, PointerRNA v
   }
 }
 
-static void rna_Constraint_transformCache_object_path_update(Main *bmain,
-                                                             Scene *scene,
-                                                             PointerRNA *ptr)
-{
-#  ifdef WITH_ALEMBIC
-  bConstraint *con = (bConstraint *)ptr->data;
-  bTransformCacheConstraint *data = (bTransformCacheConstraint *)con->data;
-  Object *ob = (Object *)ptr->id.data;
-
-  data->reader = CacheReader_open_alembic_object(
-      data->cache_file->handle, data->reader, ob, data->object_path);
-#  endif
-
-  rna_Constraint_update(bmain, scene, ptr);
-}
-
 #else
 
 static const EnumPropertyItem constraint_distance_items[] = {
@@ -2902,7 +2886,7 @@ static void rna_def_constraint_transform_cache(BlenderRNA *brna)
       prop,
       "Object Path",
       "Path to the object in the Alembic archive used to lookup the transform matrix");
-  RNA_def_property_update(prop, 0, "rna_Constraint_transformCache_object_path_update");
+  RNA_def_property_update(prop, 0, "rna_Constraint_update");
 }
 
 /* base struct for constraints */
diff --git a/source/blender/makesrna/intern/rna_modifier.c b/source/blender/makesrna/intern/rna_modifier.c
index 8a63bf1a619..4f304f97cac 100644
--- a/source/blender/makesrna/intern/rna_modifier.c
+++ b/source/blender/makesrna/intern/rna_modifier.c
@@ -1300,19 +1300,6 @@ static bool rna_SurfaceDeformModifier_is_bound_get(PointerRNA *ptr)
   return (((SurfaceDeformModifierData *)ptr->data)->verts != NULL);
 }
 
-static void rna_MeshSequenceCache_object_path_update(Main *bmain, Scene *scene, PointerRNA *ptr)
-{
-#  ifdef WITH_ALEMBIC
-  MeshSeqCacheModifierData *mcmd = (MeshSeqCacheModifierData *)ptr->data;
-  Object *ob = (Object *)ptr->id.data;
-
-  mcmd->reader = CacheReader_open_alembic_object(
-      mcmd->cache_file->handle, mcmd->reader, ob, mcmd->object_path);
-#  endif
-
-  rna_Modifier_update(bmain, scene, ptr);
-}
-
 static bool rna_ParticleInstanceModifier_particle_system_poll(PointerRNA *ptr,
                                                               const PointerRNA value)
 {
@@ -5107,7 +5094,7 @@ static void rna_def_modifier_meshseqcache(BlenderRNA *brna)
       prop,
       "Object Path",
       "Path to the object in the Alembic archive used to lookup geometric data");
-  RNA_def_property_update(prop, 0, "rna_MeshSequenceCache_object_path_update");
+  RNA_def_property_update(prop, 0, "rna_Modifier_update");
 
   static const EnumPropertyItem read_flag_items[] = {
       {MOD_MESHSEQ_READ_VERT, "VERT", 0, "Vertex", ""},