Fix T55645: broken particle Use Count option for instancing objects.

There is now a manual refresh button on the panel to update the list
of objects in case it changes, and it also gets refreshed when changing
the collection or toggling the use count option.

This is a bit more manual but the previous code of refreshing the
list while evaluating the depsgraph was unreliable.

This also fixes it to take properly take into account visibility, and
to work with linked collections for which index writing was missing.

1 files changed, 6 insertions, 34 deletions

diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index c94a565216a..79a552a5b86 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -4246,40 +4246,8 @@ static void lib_link_particlesettings(FileData *fd, Main *main)
 			}
 
 			if (part->dupliweights.first && part->dup_group) {
-				ParticleDupliWeight *dw;
-				int index_ok = 0;
-				/* check for old files without indices (all indexes 0) */
-				if (BLI_listbase_is_single(&part->dupliweights)) {
-					/* special case for only one object in the group */
-					index_ok = 1;
-				}
-				else {
-					for (dw = part->dupliweights.first; dw; dw = dw->next) {
-						if (dw->index > 0) {
-							index_ok = 1;
-							break;
-						}
-					}
-				}
-
-				if (index_ok) {
-					/* if we have indexes, let's use them */
-					for (dw = part->dupliweights.first; dw; dw = dw->next) {
-						/* Do not try to restore pointer here, we have to search for group objects in another
-						 * separated step.
-						 * Reason is, the used group may be linked from another library, which has not yet
-						 * been 'lib_linked'.
-						 * Since dw->ob is not considered as an object user (it does not make objet directly linked),
-						 * we may have no valid way to retrieve it yet.
-						 * See T49273. */
-						dw->ob = NULL;
-					}
-				}
-				else {
-					/* otherwise try to get objects from own library (won't work on library linked groups) */
-					for (dw = part->dupliweights.first; dw; dw = dw->next) {
-						dw->ob = newlibadr(fd, part->id.lib, dw->ob);
-					}
+				for (ParticleDupliWeight *dw = part->dupliweights.first; dw; dw = dw->next) {
+					dw->ob = newlibadr(fd, part->id.lib, dw->ob);
 				}
 			}
 			else {
@@ -9304,6 +9272,10 @@ static void expand_particlesettings(FileData *fd, Main *mainvar, ParticleSetting
 			}
 		}
 	}
+
+	for (ParticleDupliWeight *dw = part->dupliweights.first; dw; dw = dw->next) {
+		expand_doit(fd, mainvar, dw->ob);
+	}
 }
 
 static void expand_collection(FileData *fd, Main *mainvar, Collection *collection)