Asset System: Support custom asset library paths through Preferences

One of the core design aspects of the Asset Browser is that users can "mount"
custom asset libraries via the Preferences. Currently an asset library is just
a directory with one or more .blend files in it. We could easily support a
single .blend file as asset library as well (rather than a directory). It's
just disabled currently.

Note that in earlier designs, asset libraries were called repositories.

Idea is simple: In Preferences > File Paths, you can create custom libraries,
by setting a name and selecting a path. The name is ensured to be unique. If
the name or path are empty, the Asset Browser will not show it in the list of
available asset libraries.
The library path is not checked for validity, the Asset Browser will allow
selecting invalid libraries, but show a message instead of the file list, to
help the user understand what's going on.
Of course the actual Asset Browser UI is not part of this commit, it's in one
of the following ones.

{F9497950}

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/D9722

Reviewed by: Brecht Van Lommel, Hans Goudey

2 files changed, 37 insertions, 0 deletions

diff --git a/source/blender/makesrna/RNA_access.h b/source/blender/makesrna/RNA_access.h
index da15489370a..0b0895f9db0 100644
--- a/source/blender/makesrna/RNA_access.h
+++ b/source/blender/makesrna/RNA_access.h
@@ -697,6 +697,7 @@ extern StructRNA RNA_UVProjector;
 extern StructRNA RNA_UVWarpModifier;
 extern StructRNA RNA_UnitSettings;
 extern StructRNA RNA_UnknownType;
+extern StructRNA RNA_UserAssetLibrary;
 extern StructRNA RNA_UserSolidLight;
 extern StructRNA RNA_VertexcolorGpencilModifier;
 extern StructRNA RNA_VectorFont;
diff --git a/source/blender/makesrna/intern/rna_userdef.c b/source/blender/makesrna/intern/rna_userdef.c
index 115bc221ce1..2175cddcd7f 100644
--- a/source/blender/makesrna/intern/rna_userdef.c
+++ b/source/blender/makesrna/intern/rna_userdef.c
@@ -184,6 +184,7 @@ static const EnumPropertyItem rna_enum_userdef_viewport_aa_items[] = {
 #  include "BKE_mesh_runtime.h"
 #  include "BKE_paint.h"
 #  include "BKE_pbvh.h"
+#  include "BKE_preferences.h"
 #  include "BKE_screen.h"
 
 #  include "DEG_depsgraph.h"
@@ -335,6 +336,12 @@ static void rna_userdef_language_update(Main *UNUSED(bmain),
   USERDEF_TAG_DIRTY;
 }
 
+static void rna_userdef_asset_library_name_set(PointerRNA *ptr, const char *value)
+{
+  bUserAssetLibrary *library = (bUserAssetLibrary *)ptr->data;
+  BKE_preferences_asset_library_name_set(&U, library, value);
+}
+
 static void rna_userdef_script_autoexec_update(Main *UNUSED(bmain),
                                                Scene *UNUSED(scene),
                                                PointerRNA *ptr)
@@ -5968,6 +5975,29 @@ static void rna_def_userdef_keymap(BlenderRNA *brna)
   RNA_def_property_ui_text(prop, "Key Config", "The name of the active key configuration");
 }
 
+static void rna_def_userdef_filepaths_asset_library(BlenderRNA *brna)
+{
+  StructRNA *srna;
+  PropertyRNA *prop;
+
+  srna = RNA_def_struct(brna, "UserAssetLibrary", NULL);
+  RNA_def_struct_sdna(srna, "bUserAssetLibrary");
+  RNA_def_struct_clear_flag(srna, STRUCT_UNDO);
+  RNA_def_struct_ui_text(
+      srna, "Asset Library", "Settings to define a reusable library for Asset Browsers to use");
+
+  prop = RNA_def_property(srna, "name", PROP_STRING, PROP_NONE);
+  RNA_def_property_ui_text(
+      prop, "Name", "Identifier (not necessarily unique) for the asset library");
+  RNA_def_property_string_funcs(prop, NULL, NULL, "rna_userdef_asset_library_name_set");
+  RNA_def_struct_name_property(srna, prop);
+  RNA_def_property_update(prop, 0, "rna_userdef_update");
+
+  prop = RNA_def_property(srna, "path", PROP_STRING, PROP_FILEPATH);
+  RNA_def_property_ui_text(prop, "Path", "Path to a .blend file to use as an asset library");
+  RNA_def_property_update(prop, 0, "rna_userdef_update");
+}
+
 static void rna_def_userdef_filepaths(BlenderRNA *brna)
 {
   PropertyRNA *prop;
@@ -6140,6 +6170,12 @@ static void rna_def_userdef_filepaths(BlenderRNA *brna)
   RNA_def_property_ui_text(prop,
                            "Save Preview Images",
                            "Enables automatic saving of preview images in the .blend file");
+
+  rna_def_userdef_filepaths_asset_library(brna);
+
+  prop = RNA_def_property(srna, "asset_libraries", PROP_COLLECTION, PROP_NONE);
+  RNA_def_property_struct_type(prop, "UserAssetLibrary");
+  RNA_def_property_ui_text(prop, "Asset Libraries", "");
 }
 
 static void rna_def_userdef_experimental(BlenderRNA *brna)