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

6 files changed, 84 insertions, 23 deletions

diff --git a/source/blender/blenkernel/intern/font.c b/source/blender/blenkernel/intern/font.c
index 9431915b4e4..df1dbaa905f 100644
--- a/source/blender/blenkernel/intern/font.c
+++ b/source/blender/blenkernel/intern/font.c
@@ -125,11 +125,17 @@ static void vfont_free_data(ID *id)
 static void vfont_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
   VFont *vf = (VFont *)id;
-  if (vf->id.us > 0 || BLO_write_is_undo(writer)) {
+  const bool is_undo = BLO_write_is_undo(writer);
+  if (vf->id.us > 0 || is_undo) {
     /* Clean up, important in undo case to reduce false detection of changed datablocks. */
     vf->data = NULL;
     vf->temp_pf = NULL;
 
+    /* Do not store packed files in case this is a library override ID. */
+    if (ID_IS_OVERRIDE_LIBRARY(vf) && !is_undo) {
+      vf->packedfile = NULL;
+    }
+
     /* write LibData */
     BLO_write_id_struct(writer, VFont, id_address, &vf->id);
     BKE_id_blend_write(writer, &vf->id);
diff --git a/source/blender/blenkernel/intern/image.c b/source/blender/blenkernel/intern/image.c
index cd2ed32cd4f..f72cce8ba2e 100644
--- a/source/blender/blenkernel/intern/image.c
+++ b/source/blender/blenkernel/intern/image.c
@@ -225,14 +225,21 @@ static void image_foreach_cache(ID *id,
 static void image_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
   Image *ima = (Image *)id;
-  if (ima->id.us > 0 || BLO_write_is_undo(writer)) {
+  const bool is_undo = BLO_write_is_undo(writer);
+  if (ima->id.us > 0 || is_undo) {
     ImagePackedFile *imapf;
 
-    /* Some trickery to keep forward compatibility of packed images. */
     BLI_assert(ima->packedfile == NULL);
-    if (ima->packedfiles.first != NULL) {
-      imapf = ima->packedfiles.first;
-      ima->packedfile = imapf->packedfile;
+    /* Do not store packed files in case this is a library override ID. */
+    if (ID_IS_OVERRIDE_LIBRARY(ima) && !is_undo) {
+      BLI_listbase_clear(&ima->packedfiles);
+    }
+    else {
+      /* Some trickery to keep forward compatibility of packed images. */
+      if (ima->packedfiles.first != NULL) {
+        imapf = ima->packedfiles.first;
+        ima->packedfile = imapf->packedfile;
+      }
     }
 
     /* write LibData */
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);
       }
     }
   }
diff --git a/source/blender/blenkernel/intern/mesh.c b/source/blender/blenkernel/intern/mesh.c
index 9ccdf5189d1..53f2a85fdad 100644
--- a/source/blender/blenkernel/intern/mesh.c
+++ b/source/blender/blenkernel/intern/mesh.c
@@ -173,24 +173,53 @@ static void mesh_foreach_id(ID *id, LibraryForeachIDData *data)
 static void mesh_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
   Mesh *mesh = (Mesh *)id;
-  if (mesh->id.us > 0 || BLO_write_is_undo(writer)) {
-    /* cache only - don't write */
-    mesh->mface = NULL;
-    mesh->totface = 0;
-    memset(&mesh->fdata, 0, sizeof(mesh->fdata));
-    memset(&mesh->runtime, 0, sizeof(mesh->runtime));
-
+  const bool is_undo = BLO_write_is_undo(writer);
+  if (mesh->id.us > 0 || is_undo) {
     CustomDataLayer *vlayers = NULL, vlayers_buff[CD_TEMP_CHUNK_SIZE];
     CustomDataLayer *elayers = NULL, elayers_buff[CD_TEMP_CHUNK_SIZE];
     CustomDataLayer *flayers = NULL, flayers_buff[CD_TEMP_CHUNK_SIZE];
     CustomDataLayer *llayers = NULL, llayers_buff[CD_TEMP_CHUNK_SIZE];
     CustomDataLayer *players = NULL, players_buff[CD_TEMP_CHUNK_SIZE];
 
-    CustomData_blend_write_prepare(&mesh->vdata, &vlayers, vlayers_buff, ARRAY_SIZE(vlayers_buff));
-    CustomData_blend_write_prepare(&mesh->edata, &elayers, elayers_buff, ARRAY_SIZE(elayers_buff));
+    /* cache only - don't write */
+    mesh->mface = NULL;
+    mesh->totface = 0;
+    memset(&mesh->fdata, 0, sizeof(mesh->fdata));
+    memset(&mesh->runtime, 0, sizeof(mesh->runtime));
     flayers = flayers_buff;
-    CustomData_blend_write_prepare(&mesh->ldata, &llayers, llayers_buff, ARRAY_SIZE(llayers_buff));
-    CustomData_blend_write_prepare(&mesh->pdata, &players, players_buff, ARRAY_SIZE(players_buff));
+
+    /* Do not store actual geometry data in case this is a library override ID. */
+    if (ID_IS_OVERRIDE_LIBRARY(mesh) && !is_undo) {
+      mesh->mvert = NULL;
+      mesh->totvert = 0;
+      memset(&mesh->vdata, 0, sizeof(mesh->vdata));
+      vlayers = vlayers_buff;
+
+      mesh->medge = NULL;
+      mesh->totedge = 0;
+      memset(&mesh->edata, 0, sizeof(mesh->edata));
+      elayers = elayers_buff;
+
+      mesh->mloop = NULL;
+      mesh->totloop = 0;
+      memset(&mesh->ldata, 0, sizeof(mesh->ldata));
+      llayers = llayers_buff;
+
+      mesh->mpoly = NULL;
+      mesh->totpoly = 0;
+      memset(&mesh->pdata, 0, sizeof(mesh->pdata));
+      players = players_buff;
+    }
+    else {
+      CustomData_blend_write_prepare(
+          &mesh->vdata, &vlayers, vlayers_buff, ARRAY_SIZE(vlayers_buff));
+      CustomData_blend_write_prepare(
+          &mesh->edata, &elayers, elayers_buff, ARRAY_SIZE(elayers_buff));
+      CustomData_blend_write_prepare(
+          &mesh->ldata, &llayers, llayers_buff, ARRAY_SIZE(llayers_buff));
+      CustomData_blend_write_prepare(
+          &mesh->pdata, &players, players_buff, ARRAY_SIZE(players_buff));
+    }
 
     BLO_write_id_struct(writer, Mesh, id_address, &mesh->id);
     BKE_id_blend_write(writer, &mesh->id);
diff --git a/source/blender/blenkernel/intern/sound.c b/source/blender/blenkernel/intern/sound.c
index 8b66b1fc628..5bcc1a9553a 100644
--- a/source/blender/blenkernel/intern/sound.c
+++ b/source/blender/blenkernel/intern/sound.c
@@ -135,13 +135,19 @@ static void sound_foreach_cache(ID *id,
 static void sound_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
   bSound *sound = (bSound *)id;
-  if (sound->id.us > 0 || BLO_write_is_undo(writer)) {
+  const bool is_undo = BLO_write_is_undo(writer);
+  if (sound->id.us > 0 || is_undo) {
     /* Clean up, important in undo case to reduce false detection of changed datablocks. */
     sound->tags = 0;
     sound->handle = NULL;
     sound->playback_handle = NULL;
     sound->spinlock = NULL;
 
+    /* Do not store packed files in case this is a library override ID. */
+    if (ID_IS_OVERRIDE_LIBRARY(sound) && !is_undo) {
+      sound->packedfile = NULL;
+    }
+
     /* write LibData */
     BLO_write_id_struct(writer, bSound, id_address, &sound->id);
     BKE_id_blend_write(writer, &sound->id);
diff --git a/source/blender/blenkernel/intern/volume.cc b/source/blender/blenkernel/intern/volume.cc
index 11aa9597740..67727d87161 100644
--- a/source/blender/blenkernel/intern/volume.cc
+++ b/source/blender/blenkernel/intern/volume.cc
@@ -561,10 +561,16 @@ static void volume_foreach_cache(ID *id,
 static void volume_blend_write(BlendWriter *writer, ID *id, const void *id_address)
 {
   Volume *volume = (Volume *)id;
-  if (volume->id.us > 0 || BLO_write_is_undo(writer)) {
+  const bool is_undo = BLO_write_is_undo(writer);
+  if (volume->id.us > 0 || is_undo) {
     /* Clean up, important in undo case to reduce false detection of changed datablocks. */
     volume->runtime.grids = nullptr;
 
+    /* Do not store packed files in case this is a library override ID. */
+    if (ID_IS_OVERRIDE_LIBRARY(volume) && !is_undo) {
+      volume->packedfile = nullptr;
+    }
+
     /* write LibData */
     BLO_write_id_struct(writer, Volume, id_address, &volume->id);
     BKE_id_blend_write(writer, &volume->id);