From f5a019ed43ab07a7d265d81e8ce89d15aaff00ef Mon Sep 17 00:00:00 2001
From: Bastien Montagne <mont29>
Date: Mon, 14 Dec 2020 11:28:08 +0100
Subject: LibOverride: Do not store some heavy data from override IDs.

This commit removes geometry from meshes and shapekeys, and embedded
files, from liboverride IDs.

This data is never overrideable, there is no reason to store extra
useless copies of it in production files.

See T78944.

Note that we may add more data to be skipped on write for liboverrides
in the future, but this commit should address all the most important
cases already.

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D9810
---
 source/blender/blenkernel/intern/key.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

(limited to 'source/blender/blenkernel/intern/key.c')

diff --git a/source/blender/blenkernel/intern/key.c b/source/blender/blenkernel/intern/key.c
index 7468112b40e..433d64a5927 100644
--- a/source/blender/blenkernel/intern/key.c
+++ b/source/blender/blenkernel/intern/key.c
@@ -108,7 +108,8 @@ static void shapekey_foreach_id(ID *id, LibraryForeachIDData *data)
 static void shapekey_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
   Key *key = (Key *)id;
-  if (key->id.us > 0 || BLO_write_is_undo(writer)) {
+  const bool is_undo = BLO_write_is_undo(writer);
+  if (key->id.us > 0 || is_undo) {
     /* write LibData */
     BLO_write_id_struct(writer, Key, id_address, &key->id);
     BKE_id_blend_write(writer, &key->id);
@@ -119,9 +120,15 @@ static void shapekey_blend_write(BlendWriter *writer, ID *id, const void *id_add
 
     /* direct data */
     LISTBASE_FOREACH (KeyBlock *, kb, &key->block) {
-      BLO_write_struct(writer, KeyBlock, kb);
-      if (kb->data) {
-        BLO_write_raw(writer, kb->totelem * key->elemsize, kb->data);
+      KeyBlock tmp_kb = *kb;
+      /* Do not store actual geometry data in case this is a library override ID. */
+      if (ID_IS_OVERRIDE_LIBRARY(key) && !is_undo) {
+        tmp_kb.totelem = 0;
+        tmp_kb.data = NULL;
+      }
+      BLO_write_struct_at_address(writer, KeyBlock, kb, &tmp_kb);
+      if (tmp_kb.data != NULL) {
+        BLO_write_raw(writer, tmp_kb.totelem * key->elemsize, tmp_kb.data);
       }
     }
   }
-- 
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