Assets/IDs: Don't generate previews for object types with no real geometry

Object types like empties, cameras or lamps will just end up as empty preview
images. We can think about ways to visualize them still, but meanwhile, don't
create such an empty preview.

Differential Revision:  https://developer.blender.org/D10334

Reviewed by: Bastien Montagne, Sybren Stüvel

2 files changed, 22 insertions, 11 deletions

diff --git a/source/blender/blenkernel/intern/icons.cc b/source/blender/blenkernel/intern/icons.cc
index 97c742b1ec1..c48f3934a19 100644
--- a/source/blender/blenkernel/intern/icons.cc
+++ b/source/blender/blenkernel/intern/icons.cc
@@ -359,22 +359,30 @@ void BKE_previewimg_id_copy(ID *new_id, const ID *old_id)
 PreviewImage **BKE_previewimg_id_get_p(const ID *id)
 {
   switch (GS(id->name)) {
+    case ID_OB: {
+      Object *ob = (Object *)id;
+      /* Currently, only object types with real geometry can be rendered as preview. */
+      if (!OB_TYPE_IS_GEOMETRY(ob->type)) {
+        return NULL;
+      }
+      return &ob->preview;
+    }
+
 #define ID_PRV_CASE(id_code, id_struct) \
   case id_code: { \
     return &((id_struct *)id)->preview; \
   } \
     ((void)0)
-    ID_PRV_CASE(ID_MA, Material);
-    ID_PRV_CASE(ID_TE, Tex);
-    ID_PRV_CASE(ID_WO, World);
-    ID_PRV_CASE(ID_LA, Light);
-    ID_PRV_CASE(ID_IM, Image);
-    ID_PRV_CASE(ID_BR, Brush);
-    ID_PRV_CASE(ID_OB, Object);
-    ID_PRV_CASE(ID_GR, Collection);
-    ID_PRV_CASE(ID_SCE, Scene);
-    ID_PRV_CASE(ID_SCR, bScreen);
-    ID_PRV_CASE(ID_AC, bAction);
+      ID_PRV_CASE(ID_MA, Material);
+      ID_PRV_CASE(ID_TE, Tex);
+      ID_PRV_CASE(ID_WO, World);
+      ID_PRV_CASE(ID_LA, Light);
+      ID_PRV_CASE(ID_IM, Image);
+      ID_PRV_CASE(ID_BR, Brush);
+      ID_PRV_CASE(ID_GR, Collection);
+      ID_PRV_CASE(ID_SCE, Scene);
+      ID_PRV_CASE(ID_SCR, bScreen);
+      ID_PRV_CASE(ID_AC, bAction);
 #undef ID_PRV_CASE
     default:
       break;
diff --git a/source/blender/makesdna/DNA_object_types.h b/source/blender/makesdna/DNA_object_types.h
index 5a88ce7c9f5..e94541fdc7f 100644
--- a/source/blender/makesdna/DNA_object_types.h
+++ b/source/blender/makesdna/DNA_object_types.h
@@ -501,6 +501,9 @@ enum {
 /* check if the object type supports materials */
 #define OB_TYPE_SUPPORT_MATERIAL(_type) \
   (((_type) >= OB_MESH && (_type) <= OB_MBALL) || ((_type) >= OB_GPENCIL && (_type) <= OB_VOLUME))
+/** Does the object have some render-able geometry (unlike empties, cameras, etc.). */
+#define OB_TYPE_IS_GEOMETRY(_type) \
+  (ELEM(_type, OB_MESH, OB_SURF, OB_FONT, OB_MBALL, OB_GPENCIL, OB_HAIR, OB_POINTCLOUD, OB_VOLUME))
 #define OB_TYPE_SUPPORT_VGROUP(_type) (ELEM(_type, OB_MESH, OB_LATTICE, OB_GPENCIL))
 #define OB_TYPE_SUPPORT_EDITMODE(_type) \
   (ELEM(_type, OB_MESH, OB_FONT, OB_CURVE, OB_SURF, OB_MBALL, OB_LATTICE, OB_ARMATURE))