Asset System: Data-block asset metadata storage, reading and API

Asset metadata is what turns a regular data-block into an asset. It is a small
data-structure, but a key part of the technical design of the asset system.

The design foresees that asset data-blocks store an `ID.asset_data` pointer of
type `AssetMetaData`. This data **must not** have dependencies on other
data-blocks or data-block data, it must be an independent unit. That way we can
read asset-metadata from .blends without reading anything else from the file.
The Asset Browser will use this metadata (together with the data-block name,
preview and file path) to represent assets in the file list.

Includes:
* New `ID.asset_data` for asset metadata.
* Asset tags, description and custom properties.
* BKE code to manage asset meta-data and asset tags.
* Code to read asset data from files, without reading IDs.
* RNA for asset metadata (including tags)

Part of the first Asset Browser milestone. Check the #asset_browser_milestone_1
project milestone on developer.blender.org.

Differential Revision: https://developer.blender.org/D9716

Reviewed by: Bastien Montagne, Brecht Van Lommel

3 files changed, 12 insertions, 1 deletions

diff --git a/source/blender/makesdna/intern/CMakeLists.txt b/source/blender/makesdna/intern/CMakeLists.txt
index 2051335dd7e..a7adaa7e258 100644
--- a/source/blender/makesdna/intern/CMakeLists.txt
+++ b/source/blender/makesdna/intern/CMakeLists.txt
@@ -138,6 +138,7 @@ set(SRC
   ../../blenlib/intern/hash_mm2a.c
   ../../blenlib/intern/listbase.c
 
+  ../DNA_asset_defaults.h
   ../DNA_brush_defaults.h
   ../DNA_cachefile_defaults.h
   ../DNA_camera_defaults.h
diff --git a/source/blender/makesdna/intern/dna_defaults.c b/source/blender/makesdna/intern/dna_defaults.c
index 1a8bd25215f..3e4d5d87fb0 100644
--- a/source/blender/makesdna/intern/dna_defaults.c
+++ b/source/blender/makesdna/intern/dna_defaults.c
@@ -85,6 +85,7 @@
 #include "DNA_defaults.h"
 
 #include "DNA_armature_types.h"
+#include "DNA_asset_types.h"
 #include "DNA_brush_types.h"
 #include "DNA_cachefile_types.h"
 #include "DNA_camera_types.h"
@@ -117,6 +118,7 @@
 #include "DNA_world_types.h"
 
 #include "DNA_armature_defaults.h"
+#include "DNA_asset_defaults.h"
 #include "DNA_brush_defaults.h"
 #include "DNA_cachefile_defaults.h"
 #include "DNA_camera_defaults.h"
@@ -148,6 +150,9 @@
 #define SDNA_DEFAULT_DECL_STRUCT(struct_name) \
   static const struct_name DNA_DEFAULT_##struct_name = _DNA_DEFAULT_##struct_name
 
+/* DNA_asset_defaults.h */
+SDNA_DEFAULT_DECL_STRUCT(AssetMetaData);
+
 /* DNA_armature_defaults.h */
 SDNA_DEFAULT_DECL_STRUCT(bArmature);
 
@@ -338,7 +343,10 @@ extern const bTheme U_theme_default;
 /** Keep headers sorted. */
 const void *DNA_default_table[SDNA_TYPE_MAX] = {
 
-    /* DNA_arnature_defaults.h */
+    /* DNA_asset_defaults.h */
+    SDNA_DEFAULT_DECL(AssetMetaData),
+
+    /* DNA_armature_defaults.h */
     SDNA_DEFAULT_DECL(bArmature),
 
     /* DNA_brush_defaults.h */
diff --git a/source/blender/makesdna/intern/makesdna.c b/source/blender/makesdna/intern/makesdna.c
index 81a7da7b4d8..54d2bc88d16 100644
--- a/source/blender/makesdna/intern/makesdna.c
+++ b/source/blender/makesdna/intern/makesdna.c
@@ -139,6 +139,7 @@ static const char *includefiles[] = {
     "DNA_volume_types.h",
     "DNA_simulation_types.h",
     "DNA_pointcache_types.h",
+    "DNA_asset_types.h",
 
     /* see comment above before editing! */
 
@@ -1533,6 +1534,7 @@ int main(int argc, char **argv)
 #include "DNA_action_types.h"
 #include "DNA_anim_types.h"
 #include "DNA_armature_types.h"
+#include "DNA_asset_types.h"
 #include "DNA_boid_types.h"
 #include "DNA_brush_types.h"
 #include "DNA_cachefile_types.h"