Depsgraph: support flushing parameters without a full COW update

Avoid computationally expensive copying operations
when only some settings have been modified.

This is done by adding support for updating parameters
without tagging for copy-on-write.

Currently only mesh data blocks are supported,
other data-blocks can be added individually.

This prepares for changing values such as edit-mesh auto-smooth angle
in edit-mode without duplicating all mesh-data.
The benefit will only be seen when the user interface no longer tags
all ID's for copy on write updates.

ID_RECALC_GEOMETRY_ALL_MODES has been added to support situations
where non edit-mode geometry is modified in edit-mode.
While this isn't something user are likely to do,
Python scripts may change the underlying mesh.

Reviewed By: sergey

Ref D11377

1 files changed, 21 insertions, 0 deletions

diff --git a/source/blender/makesdna/DNA_ID.h b/source/blender/makesdna/DNA_ID.h
index 16f5f0b4ae8..15a4f8817fd 100644
--- a/source/blender/makesdna/DNA_ID.h
+++ b/source/blender/makesdna/DNA_ID.h
@@ -454,6 +454,10 @@ typedef struct PreviewImage {
 #define ID_TYPE_IS_COW(_id_type) \
   (!ELEM(_id_type, ID_LI, ID_IP, ID_SCR, ID_VF, ID_BR, ID_WM, ID_PAL, ID_PC, ID_WS, ID_IM))
 
+/* Check whether data-block type requires copy-on-write from #ID_RECALC_PARAMETERS.
+ * Keep in sync with #BKE_id_eval_properties_copy. */
+#define ID_TYPE_SUPPORTS_PARAMS_WITHOUT_COW(id_type) ELEM(id_type, ID_ME)
+
 #ifdef GS
 #  undef GS
 #endif
@@ -602,10 +606,18 @@ typedef enum IDRecalcFlag {
    *
    * When object of armature type gets tagged with this flag, its pose is
    * re-evaluated.
+   *
    * When object of other type is tagged with this flag it makes the modifier
    * stack to be re-evaluated.
+   *
    * When object data type (mesh, curve, ...) gets tagged with this flag it
    * makes all objects which shares this data-block to be updated.
+   *
+   * Note that the evaluation depends on the object-mode.
+   * So edit-mesh data for example only reevaluate with the updated edit-mesh.
+   * When geometry in the original ID has been modified #ID_RECALC_GEOMETRY_ALL_MODES
+   * must be used instead.
+   *
    * When a collection gets tagged with this flag, all objects depending on the geometry and
    * transforms on any of the objects in the collection are updated. */
   ID_RECALC_GEOMETRY = (1 << 1),
@@ -665,6 +677,10 @@ typedef enum IDRecalcFlag {
 
   ID_RECALC_AUDIO = (1 << 20),
 
+  /* NOTE: This triggers copy on write for types that require it.
+   * Exceptions to this can be added using #ID_TYPE_SUPPORTS_PARAMS_WITHOUT_COW,
+   * this has the advantage that large arrays stored in the idea data don't
+   * have to be copied on every update. */
   ID_RECALC_PARAMETERS = (1 << 21),
 
   /* Input has changed and datablock is to be reload from disk.
@@ -689,6 +705,11 @@ typedef enum IDRecalcFlag {
    * all dependent objects. */
   ID_RECALC_ANIMATION_NO_FLUSH = ID_RECALC_COPY_ON_WRITE,
 
+  /* Ensure geometry of object and edit modes are both up-to-date in the evaluated data-block.
+   * Example usage is when mesh validation modifies the non-edit-mode data,
+   * which we want to be copied over to the evaluated data-block. */
+  ID_RECALC_GEOMETRY_ALL_MODES = ID_RECALC_GEOMETRY | ID_RECALC_COPY_ON_WRITE,
+
   /***************************************************************************
    * Aggregate flags, use only for checks on runtime.
    * Do NOT use those for tagging. */